Dissertations / Theses on the topic 'Growing performance'

Optimal nutritional management of growing pigs is constrained by lack of quantitative information on the response of animals between 30 and 110 kg live weight to dietary energy content. Under 'ideal' conditions modern genotypes appear to adjust feed intake to maintain a constant DE intake over a much wider range of dietary energy concentrations than previously thought (Mullan et al, 1998). However, under commercial pen conditions, voluntary feed intake is lower, pigs respond in terms of both growth rate and feed conversion to dietary DE density considerably above the levels currently thought to maximise biological and economic responses. The present study was designed to provide information on the response of growing pigs to dietary energy content under ideal and commercial housing conditions for two growth periods 30-60kg liveweight and 60-100kg liveweight. The results of the pigs kept under individual (ideal) housed conditions were consistent with the literature in that they adjusted their voluntary feed intake with digestible energy density to maintain a constant energy intake. The results of the pigs kept in groups (commercial) housing conditions tended to increase their daily energy intake as the energy density of the feed increased. This increase in energy intake improved the growth rate of the pigs and increased the fat deposition of those pigs. Economic analysis of the experiments involving pigs in groups indicates that formulating diets to a least cost per megajoule of digestible energy is not the most profitable point to set the digestible energy density. Modelling programs need to be used to determine where the least cost per unit of growth of the pig occurs. This is the most economical digestible energy density to formulate too. This will have major impact on the cost of production of piggery operations as the cost of energy is the single most important parameter in the cost of producing a pig.

Thesis (M. Sc. Vet. Sc.)--University of Sydney, 2004.
Title from title screen (viewed 14 May 2008). Submitted in fulfilment of the requirements for the degree of Master of Science in Veterinary Science to the Faculty of Veterinary Science. Includes bibliographical references. Also available in print form.

Master of Science
Department of Animal Sciences and Industry
James S. Drouillard
Three studies were conducted to assess effects of mineral supplementation on growing cattle performance, mineral status, and in vitro fermentation. Exp. 1 was a 3-part study that measured effects of Cu source and concentration on in vitro fermentation by mixed ruminal microbes. An initial in vitro experiment was performed to identify a Cu concentration (0, 100, 200, 300, 400, or 500 mg Cu/kg substrate DM) that would yield a 50% decrease in gas production. This concentration (100 mg Cu/kg substrate) was then used to evaluate varying Cu sources in the 3rd part of Exp.1. Titration of Cu (0, 10, 20, 30, 40, 50, 60, and 70 mg Cu/kg DM substrate) linearly decreased (P < 0.01) in vitro gas production, acetate, and propionate production. Inhibition of ruminal fermentation by Cu sources (CuSO₄, CuCl₂, CuCO₃, CuO, and tribasic copper chloride) also was evaluated using an in vitro fermentation system. Sources were incorporated into cultures at 100 mg Cu/kg substrate DM, a concentration great enough to elicit an inhibitory response. Copper sulfate and CuCl₂ were more inhibitory to in vitro fermentation, as indicated by decreases in gas production, VFA, and IVDMD, and increases in pH (P < 0.01). In Exp. 2, heifers were fed 3 different free-choice minerals: salt (S), a dry mineral basemix with salt (M), and a cooked molasses block (B); M and utilized the identical basemix. Mineral source had no effect on DMI, G:F, or concentrations of plasma P and Zn (P > 0.10). Average daily gain was greatest for M (P = 0.03), and not different between S and B (P = 0.98). Liver Cu concentrations were different among treatments (P < 0.01), with M having the greatest, B intermediate, and S having the least. Total dietary mineral intake also was different among treatments (P < 0.01), and was greatest for M, intermediate for B, and the least for S (P < 0.01). Experiment 3 × 4 factorial design and evaluated minerals added as different supplement types and trace mineral concentrations (0, 1, 5, or 10×) in an in vitro batch culture fermentation. Cooked molasses mineral blocks were compared to a dry mineral premix, and a dry mineral premix + molasses block added separately. In vitro fermentation was not different between the two molasses block treatments (P > 0.01); however, addition of molasses blocks increased fermentation to a greater extent than dry mineral alone (P < 0.01). Increasing trace mineral concentration decreased fermentation linearly (P < 0.01). In conclusion, excesses of trace elements can adversely affect fermentation by ruminal microbes. Mineral status in growing cattle was reflective of mineral intake; however, block supplements may be a method to control mineral intake to minimize overconsumption.

Thesis (Ph. D.)--West Virginia University, 2000.
Title from document title page. Document formatted into pages; contains viii, 128 p. : ill. (some col.) Vita. Includes abstract. Includes bibliographical references (p. 108-115).

The objectives of this study were accomplished with two experiments in growing Bonsmara bulls (N = 68) (experiment 1), and Simmental crossbred calves (N = 132) (experiment 2). Specific objectives for experiment 1 were to characterize residual feed intake (RFI) in growing bulls, and examine relationships between RFI and performance, fertility, temperament and body composition traits. In experiment 2, the objectives were to examine stocker-phase supplementation effects on feedlot feed conversion ratio (FCR) and RFI and to characterize relationships between these feed efficiency traits, and performance and carcass traits in finishing calves. In both experiments, individual feed intakes and BW were measured. Ultrasound technology was used to measure body composition in experiment 1, while actual carcass measurements taken at harvest were used for experiment 2. Experiment 1 demonstrated that temperament affected ADG and DMI, but not FCR or RFI. Residual feed intake was not phenotypically correlated to scrotal circumference or bull fertility traits. Experiments 1 and 2 demonstrated that RFI was independent of ADG and BW, but that there was a tendency (P < 0.10) for RFI to be phenotypically correlated with 12th rib fat thickness (r = 0.20 and 0.22). However, RFI was not correlated with longissimus muscle area in either experiment. Both experiments demonstrated that low RFI (< 0.5 SD below mean RFI) calves consumed significantly (20 and 22%) less feed and had improved (21%) FCR compared to calves with high RFI (> 0.5 SD above mean RFI). Results from experiment 2 suggest that RFI measured while calves are consuming high-grain diets may be less influenced by previous level of stocker supplementation compared to FCR or residual gain efficiency traits. In summary, RFI was found to be phenotypically independent of growth rate and BW, had no effect on bull fertility or temperament traits, and was less impacted by previous plane of nutrition compared to FCR.

In the beef cattle industry, sustainable beef production is a primary focus, as it has direct effects on environmental stewardship, farm profitability, and public concerns. Research has been and is continually being conducted to evaluate alternative forages such as Brown Midrib Corn Silage (BMRCS) as a major component in growing beef cattle diets, to improve animal performance, ruminal fermentation, and economic returns. The objective of this study was to determine growth performance, ruminal fermentation characteristics, and economic returns of growing beef steers when fed a brown midrib corn silage-based TMR (BMRT) compared with a conventional corn silage-based TMR (CCST). This growing beef study was performed in a completely randomized design with 24 Angus crossbred steers (initial body weight (BW) = 258 ± 23.2 kg) to test 2 treatments: CCST vs. BMRT. All animals were placed in individual pens, and 12 animals allocated to each treatment (n = 12). All steers were adapted to the CCST for a 2-wk period prior to start of the trial. The CCST contained 48.1% CCS whereas the BMRT consisted of 49.0% BMRCS on a dry matter (DM) basis. All steers were fed once per day, and feed bunks assesed each afternoon and prior to morning feeding, which was used to determine the amount of feed to deliver to each pen the following day. The experiment lasted 84 d. For all steers, BW and ruminal fermentation characteristics were measured on wk 4, 8, and 12. Intake of DM averaged 9.54 kg/d across the treatments and was similar between the treatments. Steers fed the BMRT tended to increase average daily gain (ADG) compared to those fed the CCST (1.54 vs. 1.42 kg/d; P = 0.09). In addition, feeding the BMRT tended to increase G:F compared with the CCST (0.165 vs. 0.146; P = 0.07). Feeding the BMRT decreased ruminal pH (6.42 vs. 6.67; P < 0.01), whereas it increased total VFA concentration (P = 0.01) compared with the CCST. Feeding the BMRT decreased molar proportion of acetate (P < 0.01), but increased propionate proportion (P = 0.01), resulting in decreased acetate-to-propionate ratio compared with the CCST (P < 0.02). Steers fed BMRT increased feed margin (P = 0.05) and net return (P = 0.02) compared to those fed CCST throughout the trial. Overall data in this study indicate that feeding the BMRT to growing beef steers enhanced ruminal fermentation and beneficially shifted VFA profiles, which contributed to improved growth performance and economic performance of steers fed the BMRT.

Introduction and objectives Since 1996, the spread-out of Epizootic Rabbit Enteropathy (ERE) in European rabbit breeding stock has remarkably increased mortality and losses and impaired feed conversion, due to the large number of morbid animals. The lack of identification of an etiological agent responsible for the syndrome and the attribution of a multifactorial character to it, as well as the limitations imposed by EU legislation on the use of antibiotics, have stimulated research on feeding and management strategies capable of preventing or at least limiting the impact of enteropathy. In particular, studies in the past few years intended to specify the nutritional requirements in rabbits during weaning and post-weaning, in relation to the possibility of reducing the damages caused by enteropathy. Among the various nutrients, the most digestible fibre fractions (DF: pectins and hemicelluloses) seem to favour the health status of the animals, in addition to enhance caecal the fermentative activity and feed efficiency (Gidenne and García, 2006). By increasing soluble fibre level in starter weaning diets, C. perfringens and other opportunistic pathogens at caecal level were reduced, followed by the mortality caused by diarrhoea (Soler et al., 2003; Gómez-Conde et al., 2007). By keeping a constant ADF content and replacing starch and protein by digestible fibre (Perez et al., 2000; Gidenne et al., 2001; Marguenda et al., 2006), digestive disorders decreased and rabbit health status improved. Reducing insoluble fibre (Gutiérrez et al., 2002; Alvarez et al., 2007) and increasing the more soluble fractions (García-Ruiz et al., 1997; Carabaño et al., 2008) had also positive effects on intestinal mucosa integrity. Few are yet known nowadays on the interaction between digestible fibre and protein. Lack (<12%) or excess of protein (>18%) may favour digestive disorders and mortality, modifying caecal fermentative activity and microflora composition (Maertens e De Groote, 1988; Lebas, 1989; Carabaño et al., 2008, 2009). Reducing protein level from 18 to 16% (in diets with the same ileal digestibility) significantly reduced the presence of Clostridium perfringens and mortality by epizootic rabbit enteropathy (Chamorro et al., 2007), while further reduction from 16 to 14% did not have any effect on mortality, though reducing anaerobic bacteria at ileum (García-Palomares et al., 2006a, 2006b; Carabaño et al., 2009). The use of less digestible protein sources may also increase the nitrogen flux at caecal level and favour the development of pathogens such as E. coli and Clostridia spp, thus impairing animal health and performance (Gutiérrez et al., 2003; Chamorro et al., 2005, 2007; Carabaño et al., 2008, 2009). Given the late attention of the mass media and consumers on the use of not genetically modified raw materials, a certain interest exists in evaluating protein sources alternative to soybean, which is certainly not modified biotechnologically. Among these, sunflower meal is widely used in rabbit nutrition, usually combined with soybean meal. The use of diets based only on sunflower meal demands a careful evaluation of the aminoacidic equilibrium. The experimental activities realized in the frame of the present PhD thesis followed the general objectives of defining rabbit nutritional needs during post-weaning and fattening with special regards to the different fibrous fractions, mostly the more digestible (pectins, hemicelluloses), the starch content in relation to fibre, as well as the dietary protein supply with the aim of 1) improving rabbits intestinal conditions 2) reducing the incidence and severity of digestive pathologies 3) increasing feed efficiency, and 4) guaranteeing high growth performance and final meat quality. The objectives of the present thesis were pursued along the following four studies. Experiment 1 Digestible fibre level and substitution of soybean with sunflower meal in diets for growing rabbits. At 34 d, 216 rabbits (837±48 g LW) of both genders from a hybrid line were divided in six experimental groups of 36 units and fed ad libitum with six isoproteic diets (15.9% CP) formulated according to a 2 x 3 factorial design, with two protein sources (soybean vs. sunflower meal) and three levels of DF to ADF ratio (1.0, 1.1 and 1.2). The apparent digestibility of nutrients and the digestible energy (DE) concentration of the diets were determined in vivo (Perez et al., 1995). Caecal contents and intestinal mucosa for villi and crypts measurements were sampled at 56 d of age. Faeces and feed samples were analysed according to A.O.A.C methods (2000) and the European harmonized procedures EGRAN (2001). The content of Total Dietary Fibre (TDF) was determined through a gravimetric-enzymatic procedure that requires the treatment with α-amylase, protease and aminoglucosidase (Megazyme Int. Ireland Ltd., Wicklow, Ireland). The content of digestible fibre (DF) was calculated as the difference between the TDF and the ADF content, thus theoretically including, pectins and hemicelluloses. Volatile fatty acid concentration was measured on the supernatant by gas chromatography using the method of Osl (1988). At 76 d of age, rabbits were slaughtered in a commercial slaughterhouse and carcasses were dissected at the Department according to the international scientific protocols (Blasco et al., 1993). The pH (Xiccato et al., 1994) and the colour (CIE, 1976) of longissimus lumborum and biceps femoris were measured. The data were analyzed by ANOVA using the GLM procedure (SAS Inst. Inc., Cary, NC) and considering the effects of DF to ADF ratio and of the protein source. The effects of gender was also included in the model to analyze variability of data of growth performance, slaughter results, carcass and meat traits. Mortality, morbidity and sanitary risk were analyzed by the CATMOD procedure of SAS. The digestibility of dry matter, gross energy, crude fibre and fibrous fractions significantly increased with DF to ADF ratio, due to the higher inclusion of beet pulp and the lower inclusion of alfalfa. The digestibility and nutritive value of the diets increases with DF to ADF ratio not only for the higher presence of digestible fibre constituents, but also for the increased digestibility (9-10 points) of all fibre fractions: ADF digestibility increased from 14.6 to 25.6%; hemicelluloses digestibility from 40.3 to 49.1%; pectins digestibility from 85.0 to 93.8% (P<0.01). This increment may be associated with the lower grade of lignification and complexity of cell walls and to the higher susceptibility of structural carbohydrates to the action of digestive enzymes, animal or bacterial ones. Protein source had a more limited effect on the digestibility of nutrients. In the sunflower diets, crude protein digestibility tended to decrease (P=0.06), consistently with the lower digestibility of crude protein in sunflower meal rather than soybean meal. Ether extract and hemicelluloses digestibility were higher (P<0.001) in sunflower diets than in soybean diets, while ADF and pectins were less digestible. Nutritive value of diets was moderate and increased by DF to ADF ratio (from about 9-10 MJ/kg) regardless to the protein source and follows the current recommendations for rabbit nutrition during post-weaning. During the trial, sanitary problems were limited and unaffected by the feeding treatment. Nor intestinal mucosa traits or caecal fermentation activity were influenced by feeding treatments, while pH of caecal content was significantly reduced by increasing the DF/ADF ratio (P=0.04). By increasing DF/ADF ratio and the nutritive value of the diets, daily growth rate, live weight of rabbits and, consequently, slaughter results did not vary, while feed consumption tended to decrease, mainly in the first period of the trial, from 34 to 55 days of age, and feed conversion linearly improved (from 3.55 to 3.42 and 3.30 in the whole trial; P<0.001). Neither growth performance nor slaughter results and meat traits were affected by protein source. Experiment 2 Digestible fibre/starch ratio and protein level for feeding growing rabbits. At 32 d, 246 rabbits (837±48 g LW) of both genders from a hybrid line were divided in six experimental groups of 36 units and fed ad libitum with six diets formulated with a constant ADF level (18%), but differing in protein levels (15 vs. 17%) and DF/starch ratio (0.8, 1.5 and 2.8), according to a bi-factorial arrangement. The in vivo digestibility trial (on 60 animals from 52 to 56 d of age), the sampling of caecal content and intestinal mucosa (on 36 rabbits at 55 d), histological analyses of gut mucosa and chemical analyses of experimental diets, faeces and caecal content as well as slaughter and dissection procedure and meat quality analyses were performed according to the methodologies detailed in the first experiment. The data were analyzed by ANOVA using the GLM procedure and considering the effects of DF/starch ratio and protein level. Sex effects were also included in the model to analyze variability of data of growth performance, slaughter results, carcass and meat traits. Increasing dietary protein significantly improved dry matter (about +1 point) and nutrient digestibility. The digestible energy content varied little depending on dietary protein, however, and, therefore, DP/DE ratio was higher in diets at 16% CP than those at 15% CP. In both cases, protein supplies satisfy requirements of growing rabbits (De Blas and Mateos, 1998). Increasing DF/starch ratio, starch apparent digestibility significantly decreased (although to a low extent in absolute value), while greatly increased fibre and fibrous fractions digestibility. Dry matter and gross energy digestibility did not change significantly, however. The nutritive value of diets, that is the digestible energy (DE) content, did not change with DF/starch ratio, since energy supplied by DF was similar to that provided by starch within constant crude fibre and NDF levels. Since hemicelluloses did not change appreciably, this result may be largely ascribable to the complete digestibility of pectins (100%) and, to a lesser extent, to the general increase in digestibility of all fibrous fractions, also the less digestible ones (e.g. ADF). Even though mortality and morbidity were low during the trial, a significant effect of dietary treatment was detected. Mortality and sanitary risk tended (P=0.10-0.11) to increase in rabbits fed with the highest protein content diets. Lower DF/starch ratio diets provoke acute ERE and increased mortality (10 vs. 1.4 and 1.4%, P=0.04), though affected animals recovered faster, so the sanitary risk did not differ among the three groups. Rabbits fed the diet with the lowest DF/starch and highest protein level showed significantly higher mortality (17.1 vs. 1.5%) and sanitary risk (20.0 vs. 8.1%) compared to the other groups. The protein level did not affect neither filling of single compartment nor caecal fermentation activity, while crypt depth (P=0.02) and villi/crypt ratio (P=0.11) decreased with low protein diets. Increasing DF/starch ratio did not modify any morphometric variable, while increased the total amount of volatile fatty acids, even though at a non-significant level, and rose (P=0.02) the acetate proportion, main fermentation product, while reduced valerate proportion (P<0.01). Growth performance was satisfying for the slaughter age and the genetic type used, but not significantly affected by the experimental treatments, which only modified minor traits of carcasses and meat quality. Experiment 3 Reducing dietary protein and increasing digestible fibre/starch ratio in diets for growing rabbits. At 29 d, 282 rabbits (596±58 g LW) of both genders from a hybrid line were divided in six experimental groups of 47 units and fed ad libitum with six diets formulated with similar content of ADF (18%) and differing in crude protein level (15.0, 15.5, 17.0% CP) and DF/starch ratio (1.1, 2.0), according to a bi-factorial arrangement. Two in vivo digestibility trials were performed on 60 animals (10 per diet) from 35 to 39 d and from 56 to 60 d of age; at 38 d caecal content and jejunum mucosa were sampled from 36 rabbits (6 animals per group). Digestibility trials, caecal and gut mucosa sampling, histological analysis and chemical analyses of experimental diets, faeces and caecal contents were performed according to the methodologies previously described. At 78 d of age, rabbits were slaughtered and carcasses dissected according to the procedures described above. Nitrogen balance was also calculated on data recorded individually estimating the body N content at the various ages using the formula proposed by Szendro et al. (1998). The same data were statistically analysed in order to evaluate the effect of dietary factors on nitrogen retention, intake and excretion. The data were analyzed by ANOVA using the GLM procedure and considering the effects of protein level, DF/starch ratio as well as their interaction. The effects of sex was also included in the model to analyze variability of data of growth performance, slaughter results, carcass and meat traits. The digestibility coefficients of nutrients measured in the two digestibility trials were analyzed by a three-way ANOVA using the GLM procedure and considering the effects of age, protein level, DF/starch ratio as well as their interactions. Increasing the protein level significantly increased nutrients digestibility, and thus the nutritive value, but decreased ether extract and starch digestive utilization. The partial replacement of alfalfa by soybean and sunflower meal and the increase in barley and dried beet pulp maintained a constant digestible fibre level and decreased the less digestible fibrous fractions, thus reducing the feed transit and increasing the digestibility. Nutrient digestive efficiency significantly improved by increasing DF/starch ratio. The reduction of alfalfa, the increase of barley and dried beet pulps, at constant digestible fibre content, may explain the increase in digestibility due to the slower feed transit caused by the reduction of less digestible fibre (mainly hemicelluloses) and the increase of pectins content. Dry matter and gross energy digestibility did not change with the age of animals. Digestive utilization of crude protein significantly decreased (from 79.2 to 75.7%, P<0.001), while digestibility of starch (from 96.4 to 97.9%, P<0.001), crude fibre (from 16.7 to 22.2%, P<0.001) and of fibrous fractions (TDF, NDF, ADF, hemicelluloses) increased, except for DF. In the first period of growth (29-50 d of age), reducing the dietary protein below 15.5% significantly reduced (P<0.001) daily weight gain (from 53.1 and 55.1 g/d in diets with 15.5% and 17% protein to 49.3 g/d in diets with 14% protein) and live weight at 50 d of age (1712 and 1755 vs. 1631 g), without affecting feed intake. In the second period (50-78 d) performance was not influenced by protein level. In the overall period, rabbits fed low-protein diets showed lower growth performance than those fed high-protein diets; while those fed medium-protein diets did not differ significantly from the other groups. Feed conversion varied according to the growth rate and significantly improved in the post-weaning and whole period by increasing protein, while was not influenced in the second period. When increasing dietary protein, despite stimulating nitrogen retention, total nitrogen excretion increased from 80.4 to 95.0 and 115.0 g, corresponding to 1.64, 1.94 and 2.35 g N excreted per day. When referring to high-protein diets (=100), nitrogen excretion was reduced by 17 and 30% by decreasing the protein level in medium- and low-protein diets, while retained N decreased only by 3 and 6%, respectively. The N excretion was reduced more in the first rather than in the second period of growth. By increasing DF/starch ratio, daily growth rate during post-weaning was significantly stimulated, feed intake reduced and as a consequence feed conversion improved. From 50 days of age until slaughter, growth was similar, but the effects on feed intake and conversion remained evident and significant. As a consequence, higher DF/starch ratio increased live weight at 50 days of age, even though the differences were no longer significant at the end of the trial, reducing feed intake and conversion (P<0.001) in the whole experiment. Increasing DF/starch ratio also reduced N excretion by 5.5%, but without effecting body N retention that improved by 2%. Health status was satisfactory in all groups and not influenced by feeding treatments. By increasing the protein content from 14 to 17.0%, VFA production increased and caecal pH decreased, while ammonia did not change. Higher inclusion of barley and dried beet pulps, at constant DF content, in diets with higher protein content may explain the more intense caecal fermentative activity. By increasing DF and reducing starch, intestinal transit got slower and gut incidence tended to increase, mainly due to caecal filling. Caecal fermentative activity increased together with VFA production (from 64.0 to 78.4 mmol/l; P<0.001) reducing pH (from 5.87 to 5.71) and ammonia production (from 4.7 to 2.3 mmol/l; P<0.001). Jejunum mucosa morphometry was not influenced by dietary protein or digestible fibre level. Protein effect on live and slaughter weight reflected changes in all correlated variables: increasing dietary protein content significantly increased live weight and carcass weight and tended (P=0.09) to improve slaughter dressing percentage. Other carcass and meat characteristics were not affected. Regarding growth performance, DF/starch ratio slightly affected slaughter and carcass traits, with small variations (P<0.10) of dissectible fat and hind leg muscle/bone ratio. Experiment 4 Starch and pectin levels in diets for growing rabbit: effects on health status, digestive physiology, growth performance and carcass and meat quality. At 34 d, 240 rabbits (827±26 g LW) of both genders from a hybrid line were divided in six experimental groups of 40 units and fed ad libitum with six diets formulated according to a bi-factorial design 2 x 3, with three levels of starch (5, 10 and 15%) and two levels of pectins (5 and 10%). Health status was controlled daily to detect promptly the occurrence of diseases, especially digestive problems. The in vivo digestibility trial on 60 animals from 52 to 56 d of age, the sampling of caecal content and intestinal mucosa on 36 rabbits at 51 d, histological analyses of gut mucosa and chemical analyses of experimental diets, faeces and caecal content were performed according to the methodologies previously described. At 75 d of age, rabbits were slaughtered and carcasses dissected following procedures described above. The data were analyzed by ANOVA using the GLM procedure and considering the effects of starch and pectins level, as well as their interaction. Sex effects were also included in the model to analyze variability of data of growth performance, slaughter results, carcass and meat traits. Increasing dietary starch improved dry matter and nutrient digestibility (from 54.7% of low-starch diets to 62.9% of high-starch diets). In high-pectins diets crude fibre (8.1 to 26.4%) and all fibre fractions digestibility was higher. Extreme pectin/starch ratio diets (0.5 vs. 2.0) showed very similar digestibility and nutritive values (DE: 9.5 MJ/kg). Diet digestibility was maintained at high level by replacing barley meal with dried beet pulp, without changing the inclusion rate of alfalfa meal. The digestibility of fibre fractions changed according to the dietary pectin level: within diets at 5% pectins, digestibility of crude fibre changed in a restricted range (from 7.2% to 9.6%, P>0.05), while significant differences were found for fibre fractions; within diets at 10% pectins, digestibility increased for crude fibre (23.5 to 30.3%), NDF (34.3 to 45.1%), ADF (25.7 to 32.1%) and hemicelluloses (45.4 to 60.8%), without significant differences for pectins digestibility. Increasing dietary starch significantly increased final live weight at 75 d and daily growth and reduced feed intake with a corresponding improvement in feed conversion (3.52 to 3.31 and 3.13, P<0.001) in the whole period. During post-weaning, daily weight gain was higher (P<0.001) and feed intake tended to be lower with high-starch diets (P=0.06), while in the second period daily growth was similar, but feed intake was significantly reduced (172 to 159 g/d; P<0.001) probably due to a better chemiostatic regulation of appetite. Dietary pectins level significantly affected growth performance: increasing concentrations stimulated daily weight gain (especially during post-weaning), reduced feed intake and improved feed conversion (3.59 vs. 3.05; P<0.001). Final live weight was higher in animals fed diets containing 10% pectins compared to those fed diets with 5% pectins, both at 55 days of age and at the end of the trial. Health status was good for all rabbits (only two animals died) and caecal fermentation activity changed little with dietary treatment: N-ammonia production was higher in the caecum of animals fed low-starch diets, likely because of the higher protein intake (DP/DE: 12.9, 12.2 and 11.6 g/MJ respectively for the diets with 5, 10, and 15% starch). With increasing dietary starch, total VFA production did not change, while the increase of acetate (P=0.12) and the reduction of propionate (P<0.01) were unexpected. The chemical characteristics of the diets may explain the result obtained in this experiment: 1) even the highest level of starch used (about 16%, average value of diets L1 and H1) was compatible with the digestive capacity of the animal at the age considered (51 d) and did not produce a significant flow of undigested starch to the caecum; 2) besides, diets had a similar DF content (24.7, 23.6 and 23.8% for diets with 5, 10 and 15% starch) to ensure a comparable fermentative activity and more oriented to acetate production rather than propionate and butyrate. The increase in pectins level reduced pH (P=0.02), but had little effect on propionate and butyrate proportions. Only total VFA production tended to increase (73.8 vs. 82.8 mmol/l; P=0.10) and percentage of valerate decreased (0.43 vs. 0.35%; P<0.01) with the administration of diets containing 10% pectins. Jejunum and ileum mucosa revealed no significant differences in the villi and crypts development, but the villi height at both ileum and jejunum tended to be lower (P=0.09 and 0.10) in rabbits fed diets containing levels of starch (about 10%) recommended for the post-weaning than in those fed diets containing less (5%) or higher (15%) concentrations. The effect of dietary starch on slaughter results mainly depended on differences in animal live weight. Heavier rabbits, that received the diets with higher starch content showed higher slaughter and carcass weights and dressing percentage, lower incidence of slaughter losses and greater incidence of dissectible fat (P<0.01). The effect of increasing dietary pectins was fair and the higher slaughter weight (2628 vs. 2687 g; P<0.05) was not associated with higher slaughter dressing percentage. Gut incidence in rabbits fed high-pectins diets was significantly higher (18.5 vs. 19.0%, P<0.05) than in rabbit fed low-pectins diets. Dietary treatments did not affect meat quality, in terms of pH or colour measured on the longissimus lumborum and biceps femoris muscles 24 hours after slaughter. General discussion In all experiments, where increasing DF to ADF ratio at similar starch level were obtained by replacing alfalfa meal with beet pulp, the digestibility of dry matter, gross energy, crude fibre and fibrous fractions significantly increased. Apparent faecal digestibility of more digestible and soluble fibrous fractions (like those contained in beet pulp) may indeed reach 60-70%, while that of insoluble fractions, main constituent of alfalfa fibre, ranges from 15 to 30% (Carabaño et al., 2001; García et al., 2009). Undoubtedly, digestibility and the nutritive value of the diets increase with DF/ADF ratio, not only for the higher presence of digestible fibre constituents, but also for the increased digestibility (9-10 points) of all fibre fractions. Differently, when DF replaces starch (increasing DF/starch ratio from 0.8 until 2.8) within limited changes in ADF level (DF/ADF ratio from 0.9 to 1.2) (Experiments 1, 2), dry matter and gross energy digestibility and, therefore, the diet nutritive value did not change, since energy supplied by DF was similar to that provided by starch as also observed by others (De Blas and Carabaño, 1996; Gidenne and Bellier, 2000). In the experiments 3 and 4, the nutritive value of diets increased by increasing DF/starch ratio from 1.1-1.7 to 1.9-4.2. The contemporary increase in DF/ADF ratio (from 0.9-1.0 to 1.4-1.5) and the very low beet pulp inclusion rate in the diets with the lowest DF/starch ratio (even 0% in Experiment 3 in comparison with maximum 33-34%) could account for this result. In Experiment 4, the diets characterized by extreme values of pectins/starch ratio (5% pectin, 15% starch=0.5 and 10% pectin, 5% starch=2), showed very similar digestibility and nutritive values: with the same inclusion rate of alfalfa meal, replacing barley meal with dried beet pulp maintained diet digestibility at high level. The diet with the highest DF and starch content also showed the highest nutritive value. Comparing different protein sources, when fed the sunflower diets, rabbits showed lower crude protein digestibility (Experiment 1), consistently with the lower CP digestibility in sunflower meal than in soybean meal found by Maertens et al. (2002). The pattern of caecal fermentations did not change; neither health status nor growth performance and slaughter results were affected. The increase of dietary CP concentration (from 15 to 16% in Experiment 2 and from 14 to 17% in Experiment 3) resulted in a higher nutrient and protein digestibility because of the partial replacement of alfalfa protein by protein from soybean and sunflower meal. Effects of dietary treatments on growth performance depend on the nutritive value of diets. Increasing the DF/ADF ratio and, therefore, the nutritive value of diets, due to the chemiostatic regulation of appetite, feed consumption decreases (Gidenne and Lebas, 2005; Xiccato and Trocino, 2010b), especially in the first period of the trial and feed conversion linearly improves, even without differences in final live weight and daily weight gain (Experiment 1). The improvement of feed conversion with increasing DF content may be related to the slower intestinal transit and the increase of digestibility and nutritive value of the diets that has been also found in other previous studies (Xiccato et al., 2006a, 2008; Carraro et al., 2007; Fragkiadakis et al., 2007). In Experiment 2, increasing the DF/starch ratio has null or little effect on growth performance. Also García et al. (1993) observed that diets based on dried beet pulp did not impair growth performance when substituting starch-raw materials because of their similar nutritive value. In Experiment 3, during post-weaning, daily growth rate was significantly stimulated and feed intake reduced; as a consequence feed conversion improved by increasing DF/starch ratio. During the last weeks before slaughter, growth was similar among groups. In Experiment 4, increasing dietary pectins from 5 to 10% (with DF/starch ratio raising from 2.4 to 3.1) significantly stimulated daily weight gain (especially during post-weaning) and increased final live weight, reduced feed intake and improved feed conversion. Increasing DF/starch ratio also reduced N excretion, without effecting body N retention especially during the first rather that the second period of growth (Experiment 3). Reducing dietary protein below 15% impaired daily weight gain and live weight immediately after post-weaning (first three weeks after weaning) (Experiments 2 and 3). These results confirm previous observation showing that protein content in commercial diets for weaning and growth is higher than animal requirements (Maertens et al., 1997; Trocino et al., 2000, 2001; García-Palomares et al., 2006a, 2006b; Eiben et al., 2008). In rabbits slaughtered at 63 days of age and 2.35 kg of live weight, the reduction in dietary protein from 16 to 14% did not influence growth performance (García-Palomares et al., 2006b). In animals slaughtered later (75-90 d) and at heavier weight (2.5-3.0 kg), decreasing protein levels from the first to the second period permitted to satisfy better the protein needs during the first growth phase and reduced N excretion during the second one. In fact, during the latter period, feed intake is higher and dietary protein may be reduced without negative consequences on performance and meat quality (Maertens et al., 1997; Maertens and Luzi, 1998; Trocino et al., 2000, 2001). Equilibrium of fermentations at caecum is considered a key indicator of possible effects of nutrients and levels on rabbit digestive health. In Experiment 1, increasing DF/ADF ratio within the tested range (from 1.0 to 1.2) did not modify the VFA production, even though caecal pH was significantly reduced. This variation, even though not associated to an increase in the total VFA production as found also by Carabaño et al. (1997), may be seen favourably in view of the maintenance of an equilibrium in the caecal bacterial population and fermentation. Increasing DF and reducing starch may slow down intestinal transit and increase gut incidence, mainly due to a higher caecal repletion. As a consequence, fermentations were stimulated, total production of VFAs increased as well as the acetate proportion, while valerate incidence usually associated to the activity of amylolitic bacteria, decreased; pH and ammonia concentration also decreased (Experiments 2 and 3). Increasing the dietary pectins concentration (Experiment 4) reduced caecal pH, tended to increase total volatile fatty acids and reduced valerate incidence. Previous studies have shown a favourable and significant increase of the caecal fermentative activity by increasing the dietary content of digestible and/or soluble fibre (García et al., 2000; Falcao-e-Cunha et al., 2004). The limited levels of caecal ammonia found in all experiments and the trend to a reduction with DF/starch ratio demonstrate that DF supplies suitable carbohydrates capable of favouring the ammonia fixation into bacterial protein. One-point difference in protein between diets (from 15 to 16%) was not sufficient to significantly affect caecal fermentative activity (Experiment 2), while when dietary protein raised from 14 to 17.0%, caecal fermentation was stimulated (Experiment 3). The higher inclusion of barley and dried beet pulps, at constant DF content, may also explain the more intense caecal fermentative activity in diets with higher protein content. In all experiments of the present thesis, great attention and an important part of work were devoted to the evaluation of the conditions of intestinal mucosa in order to evaluate rabbit health status and/or susceptibility to illness. Previous studies showed that rather than the decrease in NDF content, the increase in more soluble fibrous fractions may favour the integrity of intestinal mucosa, reduce mortality and improve growth performance in young rabbits (Gutiérrez et al., 2002; Feugier et al., 2006; Álvarez et al., 2007; Gómez-Conde et al., 2007). In the present thesis, increasing DF/ADF ratio (Experiment 1), DF/starch ratio (Experiments 2, 3 and 4) and pectin concentration (Experiment 4) did not produce any remarkable alterations to the intestinal mucosa structure, both at ileum and jejunum level. Only in Experiment 4, the height of the villi at both ileum and jejunum tended to be lower (P=0.09 and 0.10) in rabbits fed diets containing levels of starch (about 10%) recommended for the post-weaning than in those fed diets containing less (5%) or higher (15%) concentrations. The lower crypt depth found with increasing dietary protein (Experiment 2) may be associated with a lower capacity of the mucosa of repairing villi damages and therefore, indirectly, may explain the higher susceptibility to digestive disorders found in rabbits fed high-protein diets. Also previous studies showed a modest or null effect of protein source, at similar protein contents, even though significant decrease of mortality due to epizootic enteropathy was observed when increasing ileal protein digestibility (Gutiérrez et al., 2002, 2003; Chamorro et al., 2007). A positive effect on the mucosa integrity has been observed in early-weaned rabbits fed diets containing animal plasma rather than soybean (Gutiérrez et al., 2000), while negative effects of legumes anti-nutritional factors have been only hypothesized (Gutiérrez et al., 2003; Cano et al., 2004). The relative uniformity in caecal equilibrium and the structure of intestinal mucosa observed was accompanied by a relatively high sanitary status in all trials. In fact, this good condition did not permit to assess correctly the effect of the dietary treatments on health condition in rabbits or on the possibility of reducing and controlling diffusion and importance of digestive disorders by epizootic rabbit enteropathy. Increasing dietary DF/ADF ratio (Experiment 1), DF/starch ratio and pectins level (Experiment 3 and 4) did not significantly affect rabbit health. Only in Experiment 2, even though mortality and morbidity were low, a significant effect of dietary treatment was detected: the lowest DF/starch ratio diets provoked acute ERE and increased mortality, though affected animals recovered faster than in other groups. The highest mortality and sanitary risk were associated to the diet with low DF/starch and high protein level in comparison with other groups (Experiment 2). Previous studies showed a positive effect of increasing DF/ADF ratio (Gómez-Conde et al., 2004; 2007; Xiccato et al., 2006a; Carraro, 2006) or replacing starch or protein with digestible fibre in iso-ADF diets (Perez et al., 2000; Soler et al., 2004) on health condition in terms of a reduction of mortality due to ERE and digestive disorders. In fact, a dietary protein excess could impair animal health, altering caecal equilibrium and promoting protein utilization for energy production, increasing N-ammonia and pH, so favouring the development of pathogen bacterial populations (Lebas et al., 1998). In fact, mortality caused by ERE significantly decreased (Gutiérrez et al., 2002, 2003; Chamorro et al., 2007) by reducing protein level and increasing ileal protein digestibility or increasing digestible fibre (Xiccato et al., 2006a; Gómez-Conde et al., 2007). In all four trials the feeding treatment hardly affected slaughter results and carcass characteristics or meat traits, confirming the little role of nutrition treatment over carcass and meat quality, since the animals are fed ad libitum balanced diets and there were no relevant differences in the final body weight (Xiccato, 1999; Hernández and Gondret, 2006; Hernández, 2008; Xiccato and Trocino, 2010b). Only the administration of diets with different levels of fat, from different sources, could change appreciably the carcass and meat characteristics (Hernández, 2008). Only when dietary protein affected growth performance and final live weight, that is at the lowest protein concentrations (14-15%) (Experiments 2 and 3), some differences were measured, confirming the results of Maertens et al. (1997) who found worse slaughter results only below 13% dietary CP. Conclusions Some major conclusions may be drawn starting from the general objectives of the present thesis, that is defining rabbit nutritional needs during post-weaning and fattening with special regards to the different fibrous fractions, mostly the more digestible ones (pectins, hemicelluloses), the starch content in relation to fibre, as well as the dietary protein supply with different aims: 1) improving rabbits intestinal conditions. Changes in main nutrients (digestible fibre, ADF, starch and protein) within the tested intervals may affect the intestinal condition of rabbits and caecum equilibrium: increasing DF at the expenses of starch or increasing protein in diets with appreciable DF supply stimulate caecal fermentation, limit ammonia production and influence caecal pH to a favourable extent for caecal bacterial population. Starch, DF and ADF level, did not affect the morphology and integrity of rabbits intestinal mucosa. 2) reducing the incidence and severity of digestive disorders. The trials were performed under optimal health status. Thus, despite the wide variations in the chemical composition of experimental diets, no effects on animal health were noticed. Therefore, we are not able to adequately evaluate the effect of the tested dietary treatments in a farm stroked by ERE. However, there is evidence that low DF/starch ratio increases mortality and affected animals recover faster. This trend is enhanced if a low DF/starch ratio (<1) in the diet is associated with high dietary protein (>16%), so diets with high DF/starch ratio (1-1.5) and moderate protein level (about 15%) are recommended. By substituting starch with DF, high dietary energy level is maintained and combined with a low flux of undigested protein at caecal level; it may reduce the sanitary risk. 3) increasing feed efficiency and N retention. The increase of dietary DF at the expenses of less digestible fibre fractions or starch (at constant ADF level) improves feed conversion, by reducing feed intake, and allows an appreciable reduction of nitrogen excretion. Starch and digestible fibre may be considered alternative in rabbit feeding and, potentially, additive: the association of high starch and DF level could results in even better results on feed conversion and profitability. 4) guaranteeing high performance and final product quality. Increasing DF/ADF ratio improves diet nutritive value and their efficiency of utilization for growth. Increasing DF/starch does not modify the nutritive value of diets and, in most cases, nor growth performance or slaughter results. Sometimes, growth may be rather stimulated, especially during the first weeks of growth when young rabbits are still developing their digestive capacity. To maximize growth performance, dietary crude protein should not be reduced below 15.5% in the first weeks of growth since the subsequent compensatory growth that rabbits show in fattening period before slaughter does not permit to recover the weight loss. Dietary protein has to be controlled both in the first and especially in the second period of growth, during which protein requirements are lower, to increase N efficiency and limit its excretion. Changes in DF, starch or protein produce significant differences in slaughter results only when capable of modifying slaughter live weight and, therefore, carcass traits directly correlated to live weight. Meat traits, pH and colour, of main muscles never change with the dietary treatment to an extent appreciable form a commercial point of view.
Introduzione e obiettivi Negli ultimi 10 anni, la diffusione dell’enteropatia epizootica del coniglio (Epizootic rabbit enteropathy, ERE) negli allevamenti europei ha aumentato la mortalità e la morbilità e, quindi, peggiorato in maniera significativa la conversione alimentare realizzata a livello aziendale. La mancata identificazione di un agente eziologico della malattia e l'attribuzione di un carattere multifattoriale alla stessa, così come i limiti imposti dalla normativa europea sull'uso di antibiotici, hanno favorito gli studi e le ricerche in materia di alimentazione e gestione degli animali per individuare strategie in grado di prevenire, o quantomeno limitare, l'impatto dell’enteropatia. Con questo obiettivo specifico, gli studi degli ultimi anni hanno inteso definire i fabbisogni nutrizionali nei conigli durante lo svezzamento ed il post-svezzamento. Tra i diversi principi nutritivi, un aumento della concentrazione di frazioni fibrose digeribili (fibra digeribile, FD = pectine ed emicellulose) è stato associato a un miglioramento dello stato di salute degli animali, oltre che a un incremento dell'attività fermentativa a livello ciecale e un miglioramento della conversione alimentare (Gidenne e García, 2006). Una maggiore concentrazione di fibra solubile nelle diete per lo svezzamento ha ridotto la presenza a livello ciecale di C. perfringens e di altri agenti patogeni opportunisti, così come la mortalità causata da diarrea (Soler e coll., 2003; Gómez-Conde e coll., 2007). Con un contenuto costante di ADF, la sostituzione di amido e proteina con fibra digeribile ha ridotto l’incidenza di disturbi digestivi e migliorato, quindi, lo stato di salute nel coniglio (Perez e coll., 2000; Gidenne e coll., 2001; Marguenda e coll., 2006). La riduzione dell’apporto di fibra insolubile (Gutiérrez e coll., 2002; Alvarez e coll., 2007) e l'aumento delle frazioni più solubili (García-Ruiz e coll., 1997; Carabaño e coll., 2008) hanno anche migliorato l’integrità, e quindi la funzionalità, della mucosa intestinale dei giovani conigli. Le informazioni sulle interazioni tra proteina e fibra digeribile sono ancora limitate. Una carenza (<12%) o un eccesso di proteina (>18%) possono favorire i disturbi digestivi e aumentare la mortalità, indurre uno squilibrio nelle attività fermentative ciecali e, quindi, nella composizione della microflora intestinale (Maertens e De Groote, 1988; Lebas, 1989; Carabaño e coll., 2008, 2009). La riduzione del livello proteico dal 18 al 16% (in diete con la stessa digeribilità ileale della proteina) ha significativamente diminuito la presenza di Clostridium perfringens e la mortalità da enteropatia epizootica (Chamorro e coll., 2007), mentre un'ulteriore riduzione dal 16 al 14% non ha avuto alcun effetto sulla mortalità, pur avendo indotto la riduzione dei batteri anaerobi a livello ciecale (García-Palomares e coll., 2006a, 2006b; Carabaño e coll., 2009). Anche l'impiego di fonti proteiche meno digeribili può aumentare il flusso di azoto a livello ciecale e favorire lo sviluppo di agenti patogeni, come E. coli e Clostridium spp., comportando così un aumento del rischio per la salute degli animali e un peggioramento delle prestazioni produttive (Gutiérrez e coll., 2003; Chamorro e coll., 2005, 2007; Carabaño e coll., 2008, 2009). Considerata l’attenzione dei mass media e dei consumatori per l'uso di alimenti non modificati geneticamente, esiste un certo interesse nel valutare fonti proteiche alternative alla soia, sicuramente non modificate a livello biotecnologico. Tra queste, la farina di semi di girasole è ampiamente utilizzata nell'alimentazione del coniglio solitamente in combinazione con la farina di soia. L'uso di diete basate sull’utilizzo esclusivo di farina di girasole come fonte proteica richiede, tuttavia, una valutazione più attenta. Le attività sperimentali realizzate nella presente Tesi di dottorato hanno inteso, in generale, definire i fabbisogni nutrizionali del coniglio in post-svezzamento e ingrasso, con particolare riguardo a frazioni fibrose, soprattutto le più digeribili (pectine, emicellulose), contenuto di amido, e livello di proteine. Nel dettaglio, obiettivi specifici della presente tesi sono stati: 1) mantenere l’equilibrio delle fermentazioni a livello ciecale; 2) ridurre la frequenza e la gravità delle patologie digestive; 3) migliorare l'efficienza di conversione alimentare e di ritenzione azotata; e 4) garantire elevate prestazioni di crescita e ottimali qualità della carcassa e della carne. Tali obiettivi sono stati perseguiti mediante la realizzazione delle seguenti quattro attività sperimentali: Contributo sperimentale n. 1 Livello di fibra digeribile e sostituzione di farina di soia con farina di girasole in diete per conigli in accrescimento. A 34 giorni di età, 216 conigli ibridi (837±48 g) di entrambi i sessi sono stati divisi in sei gruppi sperimentali da 36 unità ciascuno e alimentati ad libitum con sei diete isoproteiche (15,9% PG) formulate in base ad un disegno bi-fattoriale, con due fonti proteiche (farina di soia vs. farina di girasole) e tre rapporti FD/ADF (1,0, 1,1 e 1,2). La digeribilità apparente ed il valore energetico delle diete sono stati determinati in vivo (Perez e coll., 1995). A 56 giorni di età, è stato effettuato un campionamento dei contenuti ciecali e della mucosa intestinale per la misura dell’attività fermentativa ciecale e la misurazione dei villi e delle cripte, rispettivamente. I campioni di feci e mangime sono stati analizzati secondo AOAC (2000) e le procedure armonizzate a livello europeo (EGRAN, 2001). Il contenuto di fibra alimentare totale (TDF) è stato determinato attraverso procedura enzimatico-gravimetrica, previo trattamento con α-amilasi, proteasi e aminoglucosidasi (Megazyme int. Ireland Ltd., Wicklow, Irlanda). Il contenuto di fibra digeribile (FD) è stato calcolato come differenza tra TDF e l’ADF. La concentrazione degli acidi grassi volatili nel contenuto ciecale è stata misurata mediante gascromatografia (Osl, 1988). A 76 giorni, i conigli sono stati macellati e le carcasse sezionate secondo i protocolli scientifici internazionali (Blasco e coll., 1993). Sono stati misurati pH (Xiccato e coll., 1994) e colore (CIE, 1976) dei muscoli longissimus lumborum e biceps femoris. I dati sono stati analizzati con ANOVA utilizzando la procedura GLM (SAS Inst. Inc., Cary, NC), e considerando gli effetti del rapporto FD/ADF e delle fonti proteiche. L’effetto del sesso è stato incluso per analizzare la variabilità di dati di accrescimento, risultati di macellazione, qualità delle carcasse e della carne. La mortalità, la morbilità e il rischio sanitario sono stati analizzati con la procedura CATMOD del SAS. La digeribilità delle diete è significativamente aumentata con il rapporto FD/ADF, a causa della maggiore inclusione delle polpe di bietola a scapito dell’erba medica. Il valore nutritivo delle diete è aumentato non solo per la maggiore presenza di FD, ma anche per la maggiore digeribilità (9-10 punti) di tutte le frazioni fibrose: la digeribilità dell’ADF è aumentata dal 14,6 al 25,6%; la digeribilità delle emicellulose dal 40,3 al 49,1%; la digeribilità delle pectine dall’85,0 al 93,8% (P<0,01). Questo incremento può essere associato con il minor grado di lignificazione e complessità delle pareti cellulari e con la maggior suscettibilità dei carboidrati strutturali alle azioni enzimatiche sia animali sia batteriche. Le fonti proteiche hanno invece avuto un effetto più limitato sulla digeribilità degli alimenti. Nelle diete contenenti solo girasole, la digeribilità della proteina grezza è risultata tendenzialmente (P=0,06) inferiore a quelle delle diete a base di soia. La digeribilità dell’estratto etereo e delle emicellulose è stata maggiore (P<0,001) nelle diete a base di girasole rispetto a quelle a base di soia, mentre ADF e pectine sono risultati meno digeribili. Il valore nutritivo delle diete è stato moderato, e migliorato dall’aumento del rapporto FD/ADF, indipendentemente dalla fonte proteica, e in linea con le attuali raccomandazioni per l'alimentazione del coniglio in post-svezzamento. I problemi sanitari sono stati limitati e non influenzati dal trattamento alimentare. Le caratteristiche della mucosa intestinale e le attività fermentative ciecali non sono state influenzate dal trattamento, mentre il pH del contenuto ciecale è diminuito significativamente all’aumentare del rapporto FD/ADF (P=0,04). L’accrescimento giornaliero, il peso vivo dei conigli e, di conseguenza, i risultati di macellazione non sono variati con il trattamento alimentare, mentre, soprattutto nel primo periodo (34-55 d di età), il consumo di alimento è diminuito e la conversione alimentare migliorata linearmente all’aumentare del rapporto FD/ADF e del valore nutritivo delle diete. Né le prestazioni né i risultati di macellazione sono stati modificati dalla fonte proteica utilizzata per la formulazione delle diete. Contributo sperimentale n. 2 Rapporto fibra digeribile/amido e livello proteico nell’alimentazione di conigli in accrescimento. A 32 giorni di età, 246 conigli ibridi (837±48 g) di entrambi i sessi sono stati divisi in sei gruppi sperimentali da 36 unità ciascuno e alimentati ad libitum con sei diete formulate con un livello di ADF costante (18%), ma differenti per livello di proteina (15 vs. 17%) e rapporto FD/amido (0,8, 1,5 e 2,8) secondo un disegno sperimentale bi-fattoriale. La prova di digeribilità in vivo (su 60 animali da 52 a 56 d di età), il campionamento dei contenuti ciecali e della mucosa intestinale (su 36 conigli a 55 d), l’analisi istologica della mucosa intestinale e le analisi chimiche delle diete sperimentali, delle feci e dei contenuti cecali, nonché la macellazione, la dissezione delle carcasse e le analisi di qualità della carne sono stati effettuati secondo le metodologie riportate per il primo contributo sperimentale. I dati sono stati analizzati statisticamente come riportato per il primo contributo e considerando gli effetti del rapporto FD/amido e del livello di proteina. L’effetto del sesso è stato incluso nel modello per analizzare la variabilità di dati di accrescimento, risultati di macellazione, qualità della carcassa e della carne. L’aumento del livello di proteina alimentare ha significativamente migliorato la digeribilità della sostanza secca (circa 1 punto) e dei diversi principi nutritivi. Il contenuto di energia digeribile è variato poco e il rapporto proteina digeribile (PD)/ED è risultato maggiore nelle diete al 16% PG rispetto a quelle al 15% PG. L’aumento del rapporto FD/amido ha migliorato la digeribilità apparente dell’amido (anche se in maniera limitata in valore assoluto) e, in maniera considerevole, la digeribilità della fibra e delle frazioni fibrose, mentre non ha modificato la digeribilità della sostanza secca e dell’energia lorda. Il valore nutritivo e il contenuto di ED delle diete non sono cambiati con il rapporto FD/amido, poiché l'energia fornita dalla FD è stata simile a quella fornita dall’amido. Questo risultato può essere ascritto soprattutto alla completa digeribilità delle pectine (100%) e, in misura minore, al generale aumento della digeribilità di tutte le frazioni fibrose, anche quelle meno digeribili (per esempio, ADF). Durante la prova, sebbene mortalità e morbilità siano risultate basse, si è rilevato un effetto significativo del trattamento alimentare: mortalità e rischio sanitario sono risultati tendenzialmente (P=0,10-0,11) superiori nei conigli alimentati con le diete a maggiore tenore proteico. La somministrazione di diete a basso rapporto FD/amido ha aumentato la mortalità (10 vs. 1,4 e 1,4%, P=0,04), ma anche diminuito il numero dei conigli malati che sono arrivati alla fine della prova, seppure non significativamente, di modo che il rischio sanitario associato alla dieta non è stato differente tra i trattamenti. Per i conigli alimentati con la dieta a più basso rapporto FD/amido e maggiore livello proteico, sono state misurate maggiore mortalità (17,1 vs. 1,5%) e rischio sanitario (20,0 vs. 8,1%) rispetto ai conigli alimentati con le altre diete. Il livello proteico delle diete non ha modificato l'attività fermentativa ciecale, mentre la profondità delle cripte (P=0,02) e il rapporto villi/cripte (P=0,11) sono risultati inferiori nei conigli alimentati con le diete a minore tenore proteico. L’aumento del rapporto FD/amido non ha modificato le caratteristiche della mucosa intestinale, mentre ha aumentato la quantità totale di acidi grassi volatili, anche se in modo non significativo, e l’incidenza dell’acido acetico (P=0,02), mentre ha ridotto la percentuale di acido valerianico (P<0,01). Le prestazioni produttive sono state soddisfacenti per l’età di macellazione ed il tipo genetico usato, e non influenzate dai trattamenti sperimentali, che hanno prodotto variazioni minori delle caratteristiche della carcassa e della qualità della carne. Contributo sperimentale n. 3 Riduzione dal contenuto di proteina e aumento del rapporto fibra digeribile/amido in diete per conigli in accrescimento. A 29 giorni di età, 282 conigli ibridi (596±58 g) di entrambi i sessi sono stati assegnati a sei gruppi da 47 unità ciascuno e alimentati ad libitum con sei diete al 18% di ADF e formulate secondo un disegno bifattoriale con tre livelli di proteina grezza (15,0%, 15,5% e 17,0%) e due diversi rapporti FD/amido (1,1 vs. 2.0). Sono state realizzate due prove di digeribilità in vivo da 35 a 39 d e da 56 a 60 d di età. Le prove digeribilità, il campionamento dei contenuto ciecali e delle mucose intestinali su 36 conigli a 38 d, l’analisi dei tessuti, le analisi chimiche di diete sperimentali, feci e contenuto ciecale sono stati effettuati secondo le metodologie precedentemente descritte. A 78 giorni di età, i conigli sono stati macellati e le carcasse sezionate. Il bilancio azotato è stato calcolato sui dati individuali stimando il contenuto di N del corpo a diverse età (Szendro e coll., 1998). I risultati sono stati analizzati statisticamente considerando gli effetti di livello di proteina, rapporto FD/ amido e loro interazione. L’effetto del sesso è stato incluso nel modello per analizzare la variabilità di dati di accrescimento, risultati di macellazione, caratteristiche della carcassa e della carne. I coefficienti di digeribilità delle diete nelle due prove di digeribilità sono stati analizzati con un modello che considerava l’effetto di età, livello di proteina, rapporto FD/ amido e relative interazioni. L’incremento del livello proteico della dieta ha aumentato significativamente la digeribilità dei principi nutrienti, ad eccezione di estratto etereo e amido, e quindi il valore nutritivo delle diete. La sostituzione parziale di farina di erba medica con farine di soia e girasole e l'aumento del livello di inclusione di orzo e polpe secche di bietola hanno consentito un livello costante di fibra digeribile e ridotto il livello delle frazioni fibrose meno digeribili, riducendo così il transito di alimento e aumentando l’efficienza di utilizzazione digestiva. La digeribilità dell’energia lorda e della sostanza secca non è cambiata con l’età degli animali. L’utilizzazione digestiva della proteina è significativamente diminuita (da 79,2 a 75,7%, P<0,001), mentre è aumentata la digeribilità di amido (da 96,4 a 97,9%, P<0,001), fibra grezza (da 16,7 a 22,2%, P<0,001) e frazioni fibrose (TDF, NDF, ADF, emicellulose) ad eccezione di FD. La riduzione del livello proteico delle diete somministrate nel primo periodo (29-50 d) sotto il 15,5% ha significativamente (P<0.001) diminuito accrescimento giornaliero (da 53,1 e 55,1 g/d nelle diete con il 15,5% e il 17% PG a 49,3 g/d nelle diete al 14% PG) e peso vivo a 50 d di età (1712 e 1755 vs. 1631 g), senza modificare il consumo alimentare. Nel secondo periodo (50-78 d), le prestazioni produttive non sono state influenzate dal livello proteico della dieta. In tutto il periodo, i conigli alimentati con diete a basso contenuto di proteina sono cresciuti meno rispetto a quelli alimentati con diete a maggiore contenuto proteico, mentre apporti intermedi di PG (15,5%) non hanno prodotto risultati significativamente diversi dagli altri gruppi. La conversione alimentare è variata in base al ritmo di accrescimento ed è migliorata significativamente nel post-svezzamento e nell’intero periodo di prova con i maggiori apporti proteici. Un aumento del contenuto proteico delle diete, inoltre, pur stimolando la ritenzione di azoto, ha aumentato l’escrezione di N da 80,4 a 95,0 e 115,0 g, corrispondenti a 1,64, 1,94 e 2,35 g di N escreto al giorno. Riportando i risultati alla dieta a maggiore contenuto proteico (100), l'escrezione di N è stata diminuita del 17 e del 30% passando dal 17 al 15,5 e 14,0% di PG, mentre la ritenzione di N è diminuita solo del 3 e del 6%, rispettivamente. L'escrezione di N è stata maggiormente ridotta nel secondo piuttosto che nel primo periodo di crescita. L’aumento del rapporto FD/amido, ha significativamente migliorato l’accrescimento medio giornaliero durante il post-svezzamento, diminuito il consumo di alimento e, di conseguenza, migliorato la conversione alimentare. Da 50 giorni di età fino alla macellazione, l’accrescimento è stato simile in tutti gruppi sperimentali, mentre gli effetti sul consumo alimentare e l’indice di conversione sono rimasti evidenti e significativi. Pertanto, un maggiore rapporto FD/amido ha aumentato il peso vivo a 50 giorni di età, anche se le differenze non sono risultate più significative alla fine del ciclo produttivo, riducendo l'assunzione di alimento e la conversione (P <0.001) nel periodo di prova. Inoltre, è stata ridotta l'escrezione di N del 5,5%, ma senza effetti sulla ritenzione a livello corporeo. Lo stato sanitario è stato soddisfacente in tutti i gruppi e non influenzata dai trattamenti alimentari. L’aumento del livello proteico dal 14 al 17,0% ha aumentato la produzione di acidi grassi volatili e ridotto il valore di pH ciecale, mentre non è cambiata la concentrazione di ammoniaca. Le maggiori inclusioni di orzo e polpe secche di bietola, a parità di FD, in diete con alto tenore proteico potrebbero spiegare l’intensa attività fermentativa ciecale. Aumentando il rapporto FD/amido, il transito intestinale è stato rallentato e il peso dell’apparato digerente è risultato aumentato, soprattutto per il maggiore riempimento del cieco. L’attività fermentativa ciecale è stata stimolata come evidenziato dalla maggiore produzione totale di acidi grassi volatili (da 64,0 a 78,4 mmol/l, P<0,001), accompagnata da riduzione di pH (5,87-5,71) e di produzione di ammoniaca (da 4,7 a 2,3 mmol/l, P<0,001). La morfometria della mucosa del digiuno non è stata influenzata dal contenuto in proteina o dal livello di fibra digeribile della dieta. L’effetto del livello proteico della dieta sul peso vivo e sul peso di macellazione spiega le variazioni osservate nelle altre variabili correlate con il peso degli animali: l’aumento del contenuto proteico nella dieta ha aumentato il peso della carcassa in modo significativo e tendenzialmente (P=0,09) migliorato la resa di macellazione. Altre caratteristiche della carcassa e della carne non sono state influenzate dal trattamento. Così come per le prestazioni produttive, il rapporto FD/amido ha influenzato poco i risultati di macellazione e le caratteristiche della carcassa, con piccole variazioni (P<0,10) del grasso separabile e del rapporto muscolo/ossa misurato sull’arto posteriore. Contributo sperimentale n. 4 Livelli di amido e pectine in diete per conigli in accrescimento: effetti su stato di salute, fisiologia digestiva, prestazioni produttive e qualità della carcassa e della carne. A 34 giorni di età, 240 conigli ibridi (827±26 g) di entrambi i sessi sono stati assegnati a sei gruppi sperimentali di 40 unità ciascuno e alimentati ad libitum con sei diete formulate secondo un disegno bifattoriale, con tre livelli di amido (5, 10 e 15%) e due livelli di pectine (5 e 10%). La prova di digeribilità in vivo da 52 a 56 d di età, il campionamento dei contenuti ciecali e della mucosa intestinale a 51 d, le analisi morfometriche della mucosa intestinale e le analisi chimiche di diete sperimentali, feci e contenuti ciecali sono state effettuate secondo le metodologie precedentemente descritte. A 75 d, i conigli sono stati macellati e le carcasse sezionate. I dati sono stati analizzati considerando l’effetto di livello di amido, livello di pectine e loro interazione. L’effetto del sesso è stato incluso nel modello per analizzare la variabilità di dati di accrescimento, risultati di macellazione, caratteristiche della carcassa e qualità della carne. L’aumento del contenuto di amido alimentare ha migliorato la digeribilità della sostanza secca (dal 54,7% al 62,9%) e dei diversi principi nutritivi. L'inclusione di una maggiore quantità di polpe di bietola, superiore al 30%, in sostituzione della farina di erba medica nelle diete ricche di pectine, spiega la maggiore digeribilità della fibra grezza (dall’8,1 al 26,4%) e delle frazioni fibrose. Le diete caratterizzate da valori estremi del rapporto pectine/amido (0,5 vs. 2,0) hanno mostrato digeribilità e valore nutritivo (ED: 9,5 MJ/kg) molto simili: a parità di erba medica, la sostituzione di farina d'orzo con polpe secche di bietola ha permesso di mantenere elevata la digeribilità delle diete. L’amido dell’orzo è stato sostituito dalla fibra (pectine in particolare) delle polpe di bietola. La digeribilità delle frazioni fibrose è stata cambiata dal livello di pectine: nelle diete con il 5% di pectine, la digeribilità della fibra grezza non è cambiata (da 7,2% a 9,6%, P>0,05), a differenza di quanto misurato per le frazioni fibrose; nelle diete con il 10% pectine, la digeribilità è significativamente aumentata per fibra grezza (da 23,5 a 30,3%), NDF (da 34,3 a 45,1%), ADF (da 25,7 a 32,1%) e emicellulose (da 45,4 a 60,8%). L’aumento dell’apporto di amido ha determinato un significativo incremento di peso finale a 75 d e accrescimento giornaliero e ha ridotto il consumo di alimento con relativo miglioramento della conversione alimentare (da 3,52 a 3,31 e 3,13, P<0,001) nell’intero periodo. Durante il post-svezzamento l’accrescimento giornaliero è stato aumentato (P<0,001), mentre il consumo di alimento ha mostrato una tendenziale riduzione con la somministrazione di diete ricche di amido (P=0,06); nel secondo periodo, l’accrescimento giornaliero è stato simile fra i gruppi, mentre è rimasta evidente la riduzione del consumo di alimento (da 172 a 159 g/d, P <0,001). Un maggiore livello di pectine ha stimolato l'accrescimento degli animali (soprattutto in fase di post-svezzamento), ridotto il consumo e la conversione alimentare (3,59 vs. 3,05, P<0,001). Il peso vivo finale è risultato maggiore negli animali alimentati con diete contenenti il 10% pectine rispetto a quelli alimentati con diete al 5% di pectine, sia a 55 giorni di età che alla fine ciclo produttivo. Lo stato di salute è stato buono per tutti i conigli, con soli due animali morti nell’intero periodo sperimentale, e le fermentazioni ciecali sono state poco modificate dal trattamento alimentare: la produzione di N-ammoniacale a livello ciecale è stata maggiore negli animali alimentati con diete a basso contenuto di amido, probabilmente a causa della maggiore assunzione di proteine (PD/ED: 12,9, 12,2 e 11,6 g/MJ, rispettivamente, per le diete con 5, 10, e 15% di amido). La produzione totale di acidi grassi volatili non è cambiata con l’aumento dell’amido alimentare, mentre si è riscontrato un inatteso aumento dell’incidenza di acido acetico (P=0,12) e una riduzione dell’acido propionico (P<0,01). Le caratteristiche chimiche delle diete possono spiegare i risultati ottenuti: 1) anche il più alto livello di amido utilizzato (circa il 16%, valore medio delle diete L1 e H1) era compatibile con la capacità digestiva dell'animale all'età considerata (51 d), e non ha comportato un apporto consistente di amido non digerito al cieco; 2) inoltre, le diete avevano un tenore di FD simile (24,7, 23,6 e 23,8% per le diete con 5, 10 e 15% di amido), in grado di garantire un’attività fermentativa comparabile e orientata più alla produzione di acetato che di propionato e butirrato. L'aumento del livello di pectine ha ridotto il valore di pH ciecale (P=0,02), ma ha avuto un debole effetto sull’incidenza di propionato e butirrato. Soltanto la produzione totale di acidi grassi volatili ha mostrato un tendenziale aumento (73,8 vs. 82,8 mmol/l, P=0,10) e quella di valerato è aumentata (0,43 vs. 0,35%, P<0,01) con la somministrazione di diete al 10% di pectine. L’analisi morfometrica di ileo e digiuno non ha evidenziato significative differenze nello sviluppo dei villi e delle cripte, sebbene l’altezza dei villi sia del digiuno che del cieco abbiano evidenziato una tendenziale riduzione (P=0,09 e 0,11) nei conigli alimentati con diete contenenti livelli di amido (circa il 10%) raccomandati per il post-svezzamento, rispetto ai conigli alimentati con diete contenenti livelli inferiori (5%) o superiori (15%). L’effetto del livello di amido sui risultati di macellazione è dipeso principalmente dalle differenze nel peso vivo degli animali. I conigli più pesanti, che avevano ricevuto le diete a maggiore contenuto di amido, hanno mostrato maggiori pesi alla macellazione, pesi delle carcasse e rese di macellazione, minori perdite di trasporto e maggiore incidenza del grasso sperabile (P<0,01). L’aumento della concentrazione di pectine della dieta ha avuto un effetto debole ed il maggiore peso di macellazione (2628 vs. 2687 g, P<0,05) nei conigli alimentati con le diete al 10% di pectine non è stato associato ad una maggiore resa di macellazione. L’incidenza dell’apparato digerente è stata significativamente maggiore nei conigli alimentati con diete al 10% piuttosto che al 5% di pectine (18,5 vs. 19,0%, P<0,05). Il trattamento alimentare non ha prodotto variazioni significative della qualità della carne, in termini di pH o colore misurati sui muscoli longissimus lumborum e biceps femoris 24 ore dalla macellazione. Discussione In tutti i contributi sperimentali, quando l'aumento del rapporto FD/ADF a parità di amido è stato ottenuto sostituendo la farina di erba medica con le polpe di bietola, la digeribilità di sostanza secca, energia lorda, fibra grezza e frazioni fibrose è aumentata significativamente. La digeribilità fecale apparente delle frazioni fibrose più solubili e digeribili (come quelle contenute nelle polpe) può, in effetti, raggiungere il 60-70%, mentre quella delle frazioni insolubili, principale costituente della fibra dell’erba medica, varia dal 15 al 30% (Carabaño e coll., 2001; García e coll., 2009). Senza dubbio, la digeribilità e il valore nutritivo delle diete sono aumentati con il rapporto DF/ADF, non solo per la maggiore presenza fibra digeribile, ma anche per la maggior digeribilità (9-10 punti) di tutte le frazioni fibrose. Diversamente, quando la FD ha sostituito l’amido (crescente rapporto FD/amido da 0,8 fino a 2,8) e con limitate differenze a livello di ADF (rapporto FD/ADF da 0,9 a 1,2) (Contributi sperimentali n. 1 e 2), la digeribilità di sostanza secca e energia lorda e, di conseguenza, il valore nutritivo delle diete non sono cambiati, poiché l'energia fornita dalla FD è stata simile a quella offerta dall’amido, come osservato anche da altri autori (De Blas e Carabaño, 1996; Gidenne e Bellier, 2000). Tuttavia, nei Contributi sperimentali n. 3 e 4, il valore nutritivo delle diete è cresciuto all'aumentare del rapporto FD/amido da 1,1-1,7 a 1,9-4,2. L'aumento contemporaneo del rapporto FD/ADF (da 0,9-1,0 a 1,4-1,5) e il livello molto basso di inclusione di polpe nelle diete con il più basso rapporto FD/amido (anche 0% nel Contributo sperimentale n. 3 rispetto ad un massimo del 33-34%) potrebbero spiegare questo risultato. Nel Contributo sperimentale n. 4, le diete caratterizzate da valori estremi del rapporto pectine/amido (5% pectine, 15% amido=0,5% e 10% pectine, 5% amido=2), hanno mostrato digeribilità e valori nutritivi molto simili: con lo stesso livello di inclusione di farina di erba medica, la sostituzione di orzo con polpe di bietola ha mantenuto la digeribilità a livelli elevati. La dieta con il più alto contenuto di FD e amido ha evidenziato il più alto valore nutritivo. Confrontando diverse fonti proteiche, per le diete contenenti solo girasole è stata misurata una minore digeribilità della proteina grezza (Contributo sperimentale n. 1), coerentemente con la minore digeribilità della proteina della farina di girasole rispetto alla farina di soia (Maertens e coll., 2002). Tuttavia, la fonte proteica non ha modificato le fermentazioni ciecali, lo stato di salute, le prestazioni o i risultati di macellazione. L'aumento nella dieta della concentrazione di PG (dal 15 al 16% nel Contributo sperimentale n. 2 e dal 14 al 17% nel Contributo sperimentale n. 3), in generale, ha determinato una maggiore digeribilità delle proteine e dei principi nutritivi a causa della parziale sostituzione della proteina dell’erba medica con quelle delle farine di soia e girasole. Le conseguenze dei trattamenti alimentari sulle prestazioni produttive sono una diretta conseguenza del valore nutritivo delle diete. L’aumento del rapporto FD/ADF e, quindi, del valore nutritivo delle diete ha ridotto il consumo di alimento, per la regolazione chemiostatica dell’appetito (Gidenne e Lebas, 2005; Xiccato e Trocino, 2010b), e migliorato linearmente la conversione alimentare, pur senza differenze nel peso vivo finale e nell’accrescimento giornaliero (Contributo sperimentale n. 1). Il miglioramento della conversione alimentare all’aumentare del contenuto di FD può essere messo in relazione con il più lento transito intestinale e l’aumento della digeribilità e del valore nutritivo delle diete che è stato osservato anche in altri studi (Xiccato e coll., 2006a, 2008; Carraro e coll., 2007; Fragkiadakis e coll., 2007). Nel Contributo sperimentale n. 2, l’aumento del rapporto FD/amido non ha avuto alcun effetto apprezzabile sulle prestazioni produttive. Anche García e coll. (1993) avevano osservato che diete contenenti polpe di bietola non modificavano le prestazioni di accrescimento quanto utilizzate in sostituzione di materie prime apportatrici di amido, a causa del loro simile valore nutritivo. Nel Contributo sperimentale n. 3, durante il post-svezzamento, l’accrescimento giornaliero è stato stimolato e il consumo di alimento ridotto. Di conseguenza, la conversione alimentare è migliorata all’aumentare del rapporto FD/amido. Nelle ultime settimane prima della macellazione, le prestazioni di crescita sono risultate simili fra i diversi gruppi. Nel Contributo sperimentale n. 4, l’aumento delle pectine nelle diete dal 5 al 10% (con un rapporto FD/amido da 2,4 a 3,1) ha stimolato significativamente l’accrescimento giornaliero (soprattutto nel post-svezzamento), aumentato il peso vivo finale, ridotto il consumo e migliorato la conversione alimentare. L’aumento del rapporto FD/amido ha anche diminuito l’escrezione azotata, senza modificare la ritenzione, soprattutto nel primo periodo piuttosto che nel secondo (Contributo sperimentale n. 3). La riduzione dell’apporto proteico con la dieta al di sotto del 15% ha peggiorato l’accrescimento e il peso degli animali nel post-svezzamento (prime tre settimane dopo lo svezzamento) (Contributi sperimentali n. 2 e 3). Questi risultati confermano precedenti osservazioni relative ad un contenuto proteico nelle diete commerciali per lo svezzamento e l’accrescimento superiore rispetto ai reali fabbisogni degli animali (Maertens e coll., 1997; Trocino e coll., 2000, 2001; García-Palomares e coll., 2006a, 2006b; Eiben e coll., 2008). In conigli macellati a 63 giorni di età e 2,35 kg di peso vivo, condizioni tipiche del mercato spagnolo, la riduzione del livello proteico delle diete dal 16 al 14% non ha influenzato le prestazioni produttive (García-Palomares e coll., 2006b). In conigli macellati dopo (75-90 d) e a pesi maggiori (2,5-3,0 kg), la riduzione del livello proteico dal primo al secondo periodo ha permesso di soddisfare meglio i fabbisogni proteici nella prima fase di accrescimento e di ridurre l’escrezione azotata durante la seconda fase. In effetti, in questo ultimo periodo prima della macellazione, il consumo di alimento è maggiore e il livello proteico delle diete può essere diminuito senza conseguenze negative sulle prestazioni o sulla qualità della carcassa e della carne (Maertens e coll., 1997; Maertens e Luzi, 1998; Trocino e coll., 2000, 2001). L’equilibrio delle fermentazioni ciecali è considerato un indicatore del possibile effetto dei fattori nutrizionali sulla salute dell’apparato digerente nel coniglio. Nel Contributo sperimentale n. 1, l’aumento del rapporto FD/ADF nell’intervallo considerato (da 1,0 a 1,2) non ha modificato la produzione totale di acidi grassi volatili, sebbene sia significativamente diminuito il pH del contenuto ciecale. Questa variazione, sebbene non associata ad alcun aumento degli acidi grassi volatili totali come osservato anche da Carabaño e coll. (1997), può essere considerato favorevolmente per il mantenimento di un equilibrio della popolazione ciecale e delle fermentazioni. L’aumento del contenuto di FD e la riduzione dell’amido possono rallentare il transito intestinale e aumentare l’incidenza dell’apparato digerente, soprattutto per il maggiore riempimento del cieco. Di conseguenza, le fermentazioni sono state stimolate, la produzione totale di AGV è stata aumentata così come l’incidenza di acido acetico, mentre la percentuale di acido valerianico, di solito associata con l’attività dei batteri amilolitici, è risultata ridotta; anche il pH del contenuto ciecale e la concentrazione di ammoniaca sono risultate diminuite (Contributi sperimentali n. 2 e 3). L’aumento della concentrazione di pectine (Contributo sperimentale n. 4) è risultato in una riduzione del pH ciecale, un tendenziale aumento della produzione totale di AGV e una riduzione della percentuale di acido valerianico. Studi realizzati in precedenza avevano mostrato un favorevole e significativo aumento dell’attività fermentativa ciecale all’aumentare del contenuto di fibra digeribile e/o solubile (García coll., 2000; Falcao-e-Cunha coll., 2004). I bassi livelli di azoto ammoniacale riscontrati a livello ciecale in tutti i contributi sperimentali e la tendenza ad una riduzione con l’aumento del rapporto FD/amido dimostrano che la FD rappresenta un apporto di carboidrati capaci di favorire la fermentazione e la fissazione dell’ammoniaca nella proteina batterica. Un solo punto percentuale di differenza nel contenuto proteico delle diete (dal 15 al 16%) non è stato sufficiente per modificare in maniera significativa l’attività fermentativa ciecale (Contributo sperimentale n. 2), mentre quando la proteina grezza è stata aumentata dal 14 al 17%, le fermentazioni ciecali sono state stimolate (Contributo sperimentale n. 3). La maggiore inclusione di orzo e polpe di bietola, a livelli costanti di FD, può spiegare anche la più intensa attività fermentativa ciecale negli animali alimentati con le diete a più alto contenuto di proteina. In tutte le attività sperimentali della presente tesi, è stato dato rilievo e dedicata una quota importante di lavoro alla valutazione delle condizioni della mucosa intestinale come strumento per valutare lo stato di salute dei conigli e/o la loro suscettibilità alle malattie e ai disturbi digestivi. Ricerche precedenti avevano indicato un possibile effetto positivo dell’aumento del contenuto di frazioni fibrose solubili, piuttosto che della riduzione del contenuto di NDF, sull’integrità della mucosa intestinale, con una riduzione della mortalità ed un miglioramento delle prestazioni dei giovani conigli (Gutiérrez e coll., 2002; Feugier e coll., 2006; Álvarez e coll., 2007; Gómez-Conde e coll., 2007). Nella presente tesi, tuttavia, né l’aumento del rapporto FD/ADF (Contributo sperimentale n. 1) o FD/amido (Contributi sperimentali n. 2, 3 e 4) o la concentrazione di pectine (Contributo sperimentale n. 4) hanno modificato in maniera apprezzabile la struttura della mucosa intestinale a livello di ileo o digiuno. Solo nel Contributo sperimentale n. 4, l’altezza dei villi a livello sia di ileo sia di digiuno è risultata tendenzialmente minore (P=0,09 e 0,11) nei conigli alimentati con le diete al 10% di amido, livello raccomandato per il periodo post-svezzamento, piuttosto che in quelli che avevano ricevuto le diete a minore (5%) o maggiore (15%) contenuto. La riduzione nella profondità delle cripte trovata all’aumentare del livello proteico delle diete (Contributo sperimentale n. 2) potrebbe essere associata a una minore capacità della mucosa di riparare i danni a livello dei villi e, quindi, indirettamente, potrebbe spiegare la maggiore suscettibilità ai disturbi digestivi nei conigli alimentati con le diete ad elevato contenuto proteico. Altre ricerche realizzate in precedenza hanno evidenziato un effetto minimo o nullo della fonte di proteina, a parità di apporto proteico, anche se era stata osservata una significativa riduzione della mortalità da enteropatia epizootica all’aumentare della digeribilità ileale della proteina (Gutiérrez e coll., 2002, 2003; Chamorro e coll., 2007). Un effetto positivo sull’integrità della mucosa è stato riportato in conigli svezzati precocemente e alimentati con diete contenenti plasma animale piuttosto che soia (Gutiérrez e coll., 2000), mentre gli effetti negativi di fattori anti-nutrizionali presenti nelle leguminose sono solo stati ipotizzati (Gutiérrez e coll., 2003; Cano e coll., 2004). L’uniformità osservata per equilibrio delle fermentazioni ciecali e struttura della mucosa intestinale è stata accompagnata da uno stato di salute relativamente buono in tutte le sperimentazioni realizzate. In effetti, questa situazione così favorevole non ha permesso di verificare correttamente l’effetto dei trattamenti alimentari sulle condizioni di salute dei conigli e la possibilità di ridurre e controllare la diffusione e l’importanza dei disturbi digestivi, o meglio dell’enteropatia epizootica. Né l’aumento del rapporto FD/ADF (Contributo sperimentale n. 1) o il rapporto FD/amido o il livello di pectine (Contributi sperimentali n. 3 e 4) hanno modificato significativamente lo stato di salute degli animali. Solo nell’ambito del Contributo sperimentale n. 2, anche se mortalità e morbilità sono state piuttosto basse, è stato misurato un effetto significativo del trattamento alimentare: il più basso rapporto FD/amido ha aumentato la mortalità, ma allo stesso tempo ha ridotto il numero di animali malati che hanno comunque raggiunto la fine della prova rispetto agli altri trattamenti sperimentali. La mortalità e il rischio sanitario più alti sono stati associati alla dieta con il minore rapporto FD/amido e il maggiore contenuto proteico (Contributo sperimentale n. 2). In passato, era stato evidenziato un effetto positivo sullo stato di salute, con una riduzione della mortalità da ERE e dei disturbi digestivi, all’aumentare del rapporto FD/amido (Gómez-Conde e coll., 2004; 2007; Xiccato e coll., 2006a; Carraro, 2006) o quando amido e proteina erano state sostituite da fibra digeribile in diete con lo stesso livello di ADF (Perez e coll., 2000; Soler e coll., 2004). Un eccesso proteico potrebbe peggiorare la salute degli animali, alterando l’equilibrio ciecale e favorendo l’utilizzazione della proteina a scopo energetico, aumentando la concentrazione di N ammoniacale e il valore di pH, e favorendo così lo sviluppo di popolazioni batteriche patogene (Lebas e coll., 1998). In effetti, la mortalità da ERE è stata significativamente ridotta (Gutiérrez e coll., 2002, 2003; Chamorro e coll., 2007) dalla riduzione del livello di proteina alimentare e dall’aumento della digeribilità ileale della proteina o dall’aumento del livello di fibra digeribile (Xiccato e coll., 2006a; Gómez-Conde e coll., 2007). Nei quattro contributi sperimentali, il trattamento alimentare ha avuto un effetto molto debole sui risultati di macellazione e le caratteristiche delle carcasse o la qualità della carne, confermando il ruolo minore della nutrizione sulla qualità della carcassa e della carne in animali alimentati ad libitum con diete bilanciate e che raggiungono pesi vivi finali simili (Xiccato, 1999; Hernández e Gondret, 2006; Hernández, 2008; Xiccato e Trocino, 2010b). Alcune differenze sono state misurate quando il livello proteico della dieta ha modificato le prestazioni e il peso vivo finale degli animali, e quindi con la più bassa concentrazione proteica (14-15%) (Contributi sperimentali n. 2 e 3), confermando i risultati di Maertens e coll. (1997) che avevano riportato un peggioramento dei risultati di macellazione con diete contenenti il 13% di proteina grezza. Solo la somministrazione di diete con diversi livelli di grasso, da fonti alimentari diverse, avrebbe potuto modificare in maniera apprezzabile le caratteristiche della carcassa e della carne (Hernández, 2008). Conclusioni Le conclusioni che si possono trarre dai risultati e dalla discussione di cui sopra sono fatte partendo dall’intento generale della tesi, vale a dire la definizione dei fabbisogni nutrizionali dei conigli nelle fasi di post-svezzamento e ingrasso con riguardo alle frazioni fibrose, al contenuto di amido e il suo rapporto con la fibra, e il contenuto di proteina con diversi obiettivi specifici: 1) mantenere l’equilibrio delle fermentazioni a livello ciecale. Le variazioni dei più importanti principi nutritivi (fibra digeribile, ADF, amido e proteina) negli intervalli di concentrazione testati possono modificare la condizione intestinale e l’equilibrio ciecale nel coniglio: l’aumento del contenuto di FD in sostituzione dell’amido o l’aumento del livello proteico in diete con un buon contenuto di fibra digeribile stimolano la fermentazione ciecale, limitano la produzione di azoto ammoniacale e mantengono il pH ciecale a valori utili per lo sviluppo e l’attività della normale popolazione batterica ciecale. Né il livello di FD, di amido o di ADF, tuttavia, possono modificare la morfologia e l’integrità della mucosa intestinale. 2) ridurre la frequenza e la gravità delle patologie digestive. Nonostante le ampie variazioni di composizione chimica delle diete sperimentali, non sono stati osservati effetti sullo state di salute degli animali e, piuttosto, i livelli di amido, pectine e proteine utilizzati sono sempre stati associati ad uno stato di salute ottimale. Pertanto, non siamo in grado di valutare adeguatamente l’effetto e la possibile influenza dei trattamenti alimentari studiati sullo stato di salute degli animali in un allevamento colpito da ERE o da altri disturbi di tipo digestivo. Tuttavia, c’è una certa evidenza che un basso rapporto FD/amido aumenta la mortalità. Quest’andamento è accentuato quando un basso rapporto FD/amido della dieta (<1) è associato ad un alto contenuto proteico (>16%). Diete con alti rapporti FD/amido (1-1,5) e livelli proteici moderati (circa il 15%) sono raccomandati. In altre parole, l’aumento del livello energetico della dieta mediante l’inclusione di fibra digeribile, piuttosto che di amido, combinato con un basso flusso di proteina indigerita a livello ciecale, potrebbe ridurre il rischio sanitario. 3) migliorare l'efficienza di conversione alimentare e di ritenzione azotata. L’aumento del contenuto di FD in sostituzione delle frazioni meno digeribili o dell’amido (a livelli costanti di ADF) migliora la conversione alimentare, riducendo il consumo di alimento, e permette una buona riduzione dell’escrezione azotata. L’amido e la fibra digeribile possono essere considerati alternativi nell’alimentazione del coniglio e, potenzialmente, additivi: l’associazione di elevati livelli di amido e fibra digeribile potrebbe perfino dare migliori risultati per conversione alimentare e convenienza economica. 4) garantire elevate prestazioni di crescita e ottimali qualità della carcassa e della carne. L’aumento del rapporto FD/ADF migliora il valore nutritivo delle diete e la loro efficienza di utilizzazione per l’accrescimento. L’aumento del rapporto FD/amido non modifica il valore nutritivo delle diete o, nella maggior parte dei casi, le prestazioni produttive e i risultati di macellazione. A volte, l’accrescimento può essere stimolato, soprattutto nelle prime settimane dopo lo svezzamento, quando i conigli stanno ancora sviluppando la loro capacità di utilizzazione digestiva degli alimenti. Per massimizzare le prestazioni produttive, il livello proteico delle diete non dovrebbe scendere sotto il 15,5% nelle prime settimane del ciclo di produzione, poiché il successivo accrescimento compensativo che i conigli mostrano nelle ultime settimane prima della macellazione non permetterebbe il recupero delle differenze di peso. L’apporto proteico deve essere controllato sia nel primo sia nel secondo periodo di crescita, durante il quale i fabbisogni proteici sono minori, allo scopo di aumentare l’efficienza di utilizzazione e ridurre l’escrezione dell’azoto. Variazioni nell’apporto di FD, amido o proteina inducono differenze nei risultati di macellazione solo quando sono a livelli tali da modificare il peso di macellazione e, quindi, tutte le variabili direttamente correlate con il peso vivo. Il trattamento alimentare non è mai in grado di produrre differenze nelle caratteristiche della carne, pH e colore, dei principali muscoli che possano essere apprezzabili a livello commerciale.

Master of Science
Department of Animal Science and Industry
Jim L. Nelssen
Three experiments used 777 pigs to study the effects of fiber source; wheat middlings (midds), dried distillers grains with solubles (DDGS), and choice white grease (CWG), and reduction strategies for growing and finishing pigs. Also a fourth study utilizing 1,360 pigs was conducted to determine the effect of immunocastration (IC) and DDGS withdrawal on growth performance, carcass characteristics, fatty acid analysis, and iodine value (IV) of pork fat depots in growing and finishing pigs. Experiment 1 determined that the ingredient source of fiber (wheat middlings or DDGS) was more important than NDF level alone, for characterization of growth, carcass, and yield responses. Experiment 2 showed that a short (23 d) fiber reduction strategy was successful at fully recovering yield loss; however, a longer reduction (47 d) was necessary for further improvements in carcass fat quality (IV). Experiment 3 further proved that yield loss can be recovered with a short fiber reduction strategy (19 d), and that adding energy from CWG during the fiber reduction period can improve feed efficiency, but was unsuccessful at further improving carcass yield or carcass fat quality. Experiment 4 showed that carcass yield was lower for IC pigs than barrows regardless of dietary DDGS or withdrawal strategy. Also pigs fed 30% DDGS throughout had decreased carcass yield; however, withdrawing DDGS from the diet on d 74 was effective at recovering the yield loss. While DDGS withdrawal strategy was successful at lowering IV, but was unsuccessful at fully lowering IV to values of pigs fed the control diet throughout. Iodine values were somewhat variable within fat depot, showing the jowl and clear plate fat were less accurate in showing changes from the diet, most likely due to the fact they are deposited earlier and are slower to turnover. Iodine value tended to be greater for IC pigs than barrows on d 107, but by d 125 there were no differences in IV between IC and barrows. This dramatic improvement from d 107 to 125 could be caused by the dilution of unsaturated fatty acids, specifically C18:2 and C18:3, due to the rapid deposition of fat in IC pigs.

Pharmacological levels of inorganic forms of copper (Cu) and zinc (Zn) are frequently used in diets for pigs to improve performance and control post-weaning colibacillosis. However, the use of such forms and levels causes mineral accumulation in the soil, and is a non-sustainable practice from an environmental perspective. Alternatively, organic complexes of copper (Cu) and zinc (Zn) have been proposed to be more available to pigs, and when included at lower levels than inorganic sources of these minerals have significantly reduced mineral excretion in faeces without compromising performance. However the effect of these organic minerals fed simultaneously at low levels of inclusion has not been well studied. The general hypothesis tested in this thesis was that concentrations of Cu and Zn in faecal material would be reduced when fed in an organic (Bioplex®) form without compromising performance or mineral homeostasis in growing/finishing pigs, in comparison to Cu and Zn fed in an inorganic (sulphate) form. Two experiments were performed to test this hypothesis: Experiment 1 was designed as a 2x2 factorial arrangement of treatments, with two mineral forms (Bioplex® and Sulphate) and two inclusion levels (High and Low). The “low” levels aimed at providing 80 mg/kg of dietary Cu and Zn, and the “high” levels aimed at providing 160 mg/kg of dietary Cu and Zn. Experiment 2 was designed as a 3x2 factorial arrangement of treatments, with two mineral forms (Bioplex® and Sulphate) and three inclusion levels (Low, Medium and High). The “low” levels aimed at providing 25 mg/kg of Cu and 40 mg/kg of Zn, the “medium” levels aimed at providing 80 mg/kg of both Cu and Zn, and the “high” levels aimed at providing 160 mg/kg of both Cu and Zn in the diet. Unfortunately the Medium sulphate grower diet was contaminated with excess Zn while manufacturing, which led to the exclusion of this treatment from the study. In Experiment 1, pigs fed LB (Low Bioplex®) or HS (High Sulphate) diets grew faster (P=0.014) and their carcasses were 3.5 kg heavier (P=0.020) than LS (Low Sulphate)- or HB (High Bioplex®)-fed pigs. Pigs fed LB or HS diets had lower (P=0.001) levels of Zn in plasma, a higher (P=0.029) concentration of Zn in the pancreas and a lower (P=0.020) concentration of Zn in bone than pigs fed LS or HB diets. The concentration of Cu in liver increased (P=0.017) with the concentration in the diet as did Cu and Zn levels in faeces (P<0.001) without any difference between mineral forms. Feed conversion ratio (FCR) tended to be improved (P=0.062) by the inclusion of Bioplex® in the diet. The inclusion of Bioplex® reduced (P=0.003) subcutaneous fat depth at the P2 site by 2.2 mm compared to the sulphate. In Experiment 2, there was no difference (P>0.05) in growth rate between experimental diets, but again there was an overall improvement (P=0.012) in FCR when Bioplex® were included. Blood and tissue Cu and Zn concentrations were within normal physiological ranges in all treatments, supporting a reduction of Cu and Zn levels in the diet. Only Zn level in plasma during the growing phase and Cu and Zn concentration in tissues increased (P<0.001) with the addition in the diet. None of the biomarkers of Cu or Zn status analysed in the pigs showed any difference between the inorganic and the Bioplex® forms. Copper and Zn concentrations in faecal material decreased (P<0.001) with their inclusion in the diet, and only in the finishing collection there was a further decrease of 10% in Zn faecal concentration when Bioplex® was included instead of the sulphate at similar low levels. Carcass and meat quality measures were independent of the Cu and Zn form or level, however a higher proportion of carcasses from LB-fed pigs had <14 mm subcutaneous fat depth at the P2 site. The inclusion of Bioplex® failed to have a significant effect on Cu excretion and its inclusion had an inconsistent effect on Zn excretion. The overall findings from this thesis partially supported the hypothesis that the inclusion of Bioplex® would reduce the concentration of Cu and Zn in faeces compared to the inclusion of inorganic forms at similar inclusion levels. Nevertheless, total Cu and Zn levels in growing/finishing pig diets could be reduced from 160 mg/kg of both Cu and Zn to 30 mg/kg Cu and 60 mg/kg Zn, in either the sulphate or the Bioplex® form, without negatively affecting performance or mineral homeostasis in the pigs and significantly reducing Cu and Zn excretion (between 50 and 80%). The advantage of including Bioplex® instead of sulphates was in the improvement in FCR. Carcass and meat quality were independent of the form and level of dietary Cu and Zn.

Pour répondre à la demande croissante de bois et pour préserver les forêts primaires, les méthodes de sylviculture les plus dynamiques ont été privilégiées de manière générale sur la planète.. Les objectifs de la recherche étaient 1) déterminer le point de démarcation/ âge de transition entre le bois juvénile et le bois mature sur sengon (Falcataria moluccana), jabon(Anthocephalus cadamba Miq.), peuplier (Populus sp) et douglas (Psedotsuga menziesii); 2) analyser l'effet de la juvénilité sur un fissuration cyclique, la rugosité et de mouillage; 3) analyser l'effet de la fissuration cyclique et juvénilité sur la résistance à l'adhérence de la colle et les propriétés mécaniques du LVL en flexion; et 4) appliquer un nouveau modèle analytique pour estimer la variation du module d'élasticité du lamibois (sengon et jabon) depuis la moelle vers l'écorce. A partir de la longueur des fibres, le point de démarcation entre le bois juvénile et le bois mature ont été estimés. Pour les essences sengon and jabon, les placages obtenus à partir du cœur des arbres, réputés juvéniles, sont plus fissurés plus rugueux et avec une haute mouillabilité comparativement à ceux obtenus à partir du bois près de l’écorce (plus mature). Une phase d’étuvage préliminaire des bois dans un bain d’eau chaude à 75°C pendant 4 heures a permis d’améliorer sensiblement la qualité des placages en diminuant la fissuration, la rugosité et s’accompagne d’une augmentation de la mouillabilité. La résistance à l'adhérence de la colle, et les modules élastiques et de rupture spécifiques (SMOE et SMOR) du LVL (jabon et sengon) diminuent à mesure que la fréquence de fissure augmente ou en partant de l'écorce vers la moelle. L'avantage de l'utilisation de placages en peuplier de bois mature a été prouvé avec une amélioration de 15 à 20% en moyenne pour les propriétés mécaniques, pour un poids de panneau comparable. Pour le douglas, l'utilisation de placages de bois mature dans la constitution des panneaux de LVL permet également d’améliorer les performances en flexion (de 7 à 22 % sur el MOR). Le modèle analytique a été utilisé afin de prédire les variations du module élastique allant de la moelle à l’écorce. Il permet à partir d’un grand nombre de combinaisons d’estimer le potentiel issu d’une ressource donnée. Pour le contexte de l’étude qui représente bien le potentiel sylvicole de l’Indonésie, la proportion de bois juvénile étant quasi-totale (100%), l’action de trier les placages n’est pas apparue comme pertinente
The development of plantation and community forest to meet wood demand in society has produced fast growing wood species. The research objectives were 1) to determine demarcation point/transition age between juvenile and mature wood on sengon (Falcataria moluccana), jabon (Anthocephalus cadamba Miq.), poplar (Populus sp) and douglas fir (Psedotsuga menzii); 2) to analyze the effect of juvenility on lathe check, surface roughness and wettability; 3) to analyze the effect of lathe check and juvenility on glue bond strength and laminated veneer lumber (LVL) bending properties; and 4) to apply a new analytical model to determine the variation of specific MOE LVL values of sengon and jabon from pith to bark. Based on fiber length trait, the demarcation point between juvenile and mature wood were approximately at segmented rings 17th (sengon) and at segmented ring 24th (jabon). While, transition age of poplar cultivars and douglas-fir, transition age happened approximately at 12 years old and 18 years old, respectively. The results showed that wood near pith on sengon and jabon resulted veneers with higher lathe check, rougher surface and high wettability, while wood near bark resulted veneers with lower lathe check, smoother surface and low wettability. Glue bond strength, Specific MOE (SMOE) and Specific MOR (Modulus of Rupture) of sengon and jabon LVL were decreased as the frequency of lathe check increased or those strength values increased from pith to bark. The advantage of using poplar veneers from mature wood was proved with an improvement of 15 to 20% on average for mechanical properties, while for douglas-fir, was 7 to 22%. An analytical model was used to predict the variation of the LVL mechanical characteristics using different scenarios. According to the context of this study assumed to be close to the Indonesian resource there is no need to sort veneers since most of the tree is juvenile wood for logs no older than 7

Master of Science
Department of Animal Sciences and Industry
Joel M. DeRouchey
A total of 6,858 pigs were used in 6 experiments to evaluate the effects of crude glycerol, dried distillers grains with solubles (DDGS), Ractopamine HCl (RAC), NutriDense corn, and feeder adjustment on growing and finishing pig performance. In Exp. 1, pigs were fed diets with 0, 2.5, or 5% crude glycerol with 0 or 20% DDGS. Adding DDGS increased ADFI and decreased G:F with no differences for pigs fed glycerol. Neither glycerol nor DDGS affected any carcass characteristics. Pigs fed DDGS had increased iodine value in carcass fat. In Exp. 2, pigs were fed diets with 0 or 5% glycerol with 0 or 7.5 ppm RAC. Feeding RAC increased ADG and G:F and decreased ADFI while glycerol tended to improve G:F. Ractopamine HCl improved carcass traits. Loin chop drip loss worsened when glycerol and RAC were added separately, however, drip loss decreased when the combination of both were fed. Glycerol did not affect loin characteristics. Neither RAC nor glycerol influenced iodine value of carcass fat. Exp. 3 and 4 were conducted to determine the 4th limiting amino acid in diets containing NutriDense corn. In Exp. 3, pigs fed the positive control and the diet with added Ile, Trp, and Val (in combination) had greater ADG. Pigs fed added Ile or Trp had greater ADG than pigs fed the negative control indicates these amino acids were co-4th limiting for 37 to 59 kg pigs. In Exp. 4, pigs fed the positive control, added Trp, or the combination of added Ile, Trp and Val had greater ADG then pigs fed the negative control or pigs fed either Ile or Val indicates these amino acids were co-4th limiting for 77 to 100 kg pigs. Exp. 5 and 6 evaluated feeder adjustment on growth performance of finishing pigs. In Exp. 5, reducing feeder opening decreased ADFI. In Exp. 6, pigs were fed at three feeder opening and either a corn-soybean meal or byproduct-based diet. Diet type did not affect pig performance. Widening feeder openings increased ADG and ADFI. Feeder setting tended to influence G:F with the best G:F at the intermediate opening.

Cette thèse examine les déterminants de la performance économique des coopératives agricoles. Elle porte plus précisément sur le cas des coopératives vinicoles du Languedoc-Roussillon qui constituent, avec 70% de la production régionale, le moteur de ce bassin de production viticole.Grâce à une approche multi paradigmatique de la gouvernance (théorie de l'agence, théorie des parties prenantes et théorie cognitive), ce travail analyse l'influence de ces différentes modes de gouvernance et des investissements immatériels qui y sont liés sur la performance économique au sens large (amont, aval et financière).Cette thèse distingue, à travers le « dilemme coopératif », la notion de performance à court terme, axée sur l'optimisation du revenu des associés coopérateurs, et celle de performance à long terme, focalisée sur la création de richesse pour l'entreprise coopérative.Cette recherche applique une méthodologie alliant approche qualitative essentiellement exploratoire et approche quantitative confirmatoire. L'analyse s'appuie sur 25 entretiens qualitatifs semi-directifs auprès de dirigeants ainsi que sur 87 enquêtes quantitatives réalisées à l'aide d'un questionnaire et traitées partiellement grâce à l'outil d'intelligence économique COOPERFIC®. Les résultats montrent que la gouvernance coopérative résulte bien d'une combinaison complexe de trois dimensions complémentaires (disciplinaire, partenariale et cognitive) qui ont chacune une influence notable sur la performance économique. En matière purement financière, il apparaît que la dimension disciplinaire de la gouvernance peut entraîner soit un équilibre de la performance orientée vers le court terme (optique adhérents), soit un équilibre axé sur le long terme (optique direction et salariés). Pour ce qui est de la dimension partenariale, elle est porteuse d'un accroissement général de la performance financière (à court et long terme). Enfin, une forte dimension cognitive provoque, de son côté, un accroissement exclusif de la performance financière à long terme, en lien avec une stratégie d'investissements immatériels prononcée, elle-même déterminée par le niveau d'implication des acteurs dans la gouvernance cognitive.Cette étude a ses limites car elle repose principalement sur le point de vue des dirigeants salariés et concerne un peu moins de la moitié des coopératives vinicoles du Languedoc-Roussillon. Toutefois, jusqu'à présent, très peu de recherches empiriques ont été menées sur le lien entre gouvernance et performance des coopératives agricoles, ainsi que sur le rôle essentiel des investissements immatériels dans cette relation. Cette thèse contribue donc à la connaissance des modes de gouvernance dans la coopération agricole et, plus généralement, à celle des déterminants de la performance des coopératives agricoles. Elle est, sur le plan académique, une contribution à la littérature gestionnaire portant sur la gouvernance des coopératives agricoles, ainsi que sur leur performance
This thesis deals with the economic performance factors of agricultural cooperatives and more precisely of wine production cooperatives in Languedoc-Roussillon, which account for 70% of regional production and drive growth of wine production development in the region. Using a multi-paradigmatic approach to governance (agency theory, stakeholder theory, as well as cognitive theory), this work analyses the influence of different modes of governance and intangible investments on broader economic performance (upstream, downstream, and financial).This thesis maps out the “cooperative dilemma”: short-term performance based on optimizing cooperative members' incomes versus long-term performance focusing on value creation for the cooperative. This research applies a methodology combining a qualitative approach, essentially exploratory, with a confirmatory quantitative approach. Analysis was based on 25 semi-structured qualitative interviews of managers as well as 87 quantitative surveys using a questionnaire and partially evaluated using the economic data base COOPERFIC®.Results show that cooperative governance is a result of a complex combination of three complementary dimensions (disciplinary dimension, partnerships, and the cognitive), each of which has a significant influence on economic performance. In purely financial terms, it seems the disciplinary dimension of governance can lead to either a performance balance geared to the short term (vision of members) or long term (vision of management and employees. Stakeholders approach lead to better financial performance both in the short and long terms. Finally, a strong cognitive approach to governance leads to better financial performance only in the long term, when linked to a well-developed strategy of intangible investments, itself determined by the level of implication of agents involved in the cognitive governance.This study has its limits since it is based mainly on the point of view of salaried managers and concerns a little less than half of the wine cooperatives in Languedoc-Roussillon. Nevertheless, until now, very little empirical research has been carried out on the link between governance and performance of agricultural cooperatives, as well as the essential role intangible investments play in their relationship. Consequently this thesis contributes to our knowledge of styles of governance in agricultural cooperatives, and more generally to what determines the performance of agricultural cooperatives. From an academic point of view, it is a contribution to writing on managing agricultural cooperatives and how they perform

La producción mundial de biocombustibles denominados bioetanol y biodiesel se ha incrementado en la última década, como alternativa a los combustibles fósiles. Brasil produce etanol a partir de la caña de azúcar, EEUU a partir de maíz, mientras que en Europa y Canadá, el insumo más utilizado es el grano de trigo. En España las principales plantas de biocombustible utilizan maíz, trigo y cebada, para obtener etanol, básicamente. Esta situación ha generado cambios importantes en el mercado mundial de granos, por un lado, encareciéndo el precio de las materias primas tradicionales y en consecuencia el coste de los piensos, y por otro lado, ofertando nuevas materias primas, tales como los denominados granos secos de destilería con solubles o DDGS (Dried Distillers Grains with Solubles), que pueden ser destinadas a la alimentación animal si son valoradas nutritivamente para las posibles especies animales de destino, entre las que podrían encontrarse los conejos. Dado que los insumos y los procesos de producción industrial de bioetanol presentan algunas variaciones, la calidad de los DDGS generados varía consecuentemente en su composición química y su valor nutritivo, pero estas posibles fuentes de variación han sido poco estudiadas. La cunicultura es una actividad productiva muy importante en Europa, especialmente en Francia, Italia, y España, cuyos costes de producción se han incrementado en especial en el rubro de la alimentación, que constituye entre el 50 a 70% del coste total, por las razones antes señaladas.Los DDGS se han incorporado en la dieta de vacuno, aves y cerdos, pero la información relativa a su utilización en conejos es muy escasa. En este contexto, parece necesario evaluar el potencial nutritivo y el comportamiento productivo de los DDGS en piensos de conejos.
Alagón Huallpa, G. (2013). USE OF BARLEY, WHEAT AND CORN DISTILLER'S DRIED GRAIN WITH SOLUBLES IN DIETS FOR GROWING RABBITS: NUTRITIVE VALUE, GROWTH PERFORMANCE AND MEAT QUALITY [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/27648
TESIS

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Conselho Nacional de Desenvolvimento Científico e Tecnológico
Um experimento foi realizado para avaliar se uma redução na proteína bruta na dieta e grupo genético (GG) afetam o desempenho animal, a eficiência alimentar e as características de carcaça de bovinos de corte em diferentes fases de confinamento. Quarenta e quatro animais (22 Nelore e 22 mestiças F1 Angus x Nelore), com 8 meses de idade e peso corporal em jejum (PCj) inicial = 218,6 ± 2,15 kg (Nelore = 211,5 kg; Angus x Nelore = 225,7 kg) foram utilizados neste experimento. Oito animais (4 de cada grupo genético) foram abatidos no início do experimento, tendo sido utilizados como base de referência para estimar a composição química corporal inicial. Os 36 touros restantes foram distribuídos aleatoriamente a um dos três tratamentos. O experimento foi conduzido em delineamento inteiramente casualizado, com seis repetições, em esquema fatorial 2x3. Os fatores foram dois grupos genéticos (Nelore e cruzados F1 Angus x Nelore - A × N) e três teores de proteína bruta (PB) (100, 120 e 140 g / kg MS). O período experimental foi de 224 dias, sendo dividido em 2 fases (Crescimento = 112 dias, e Terminação = 112 dias). No final do período experimental, os animais foram sacrificados para avaliar a sua composição química corporal, e as características da carcaça. Mestiços A × N apresentaram um CMS (%PV) superior (19,28) em relação ao Nelore (18,26), e também maior GMD (A × N = 1,18; Nelore = 0,88 kg / d), independentemente do estágio de crescimento ou PB. Mestiços A × N tinham uma maior ingestão de todos os nutrientes, independentemente do PB ou da fase de crescimento. Mestiços A × N terminaram o experimento mais pesados do que Nellore, uma vez que apresentaram maior GMD e foram mais eficientes quando comparados com animais da raça Nelore. CMS não diferiu (P>0,05) entre os PB dentro de estágios de crescimento, no entanto, aumentou ao longo do tempo. Animais alimentados com 14% PB tiveram um CMS (%PV) inferior durante a fase de crescimento, no entanto, diferenças foram desaparecendo durante aterminação. Durante fase de crescimento, os animais alimentados com 10% PB tiveram um GMD menor em comparação com os animais alimentados com 12 e 14% PC, que não diferiram entre si. No entanto, durante a terminação, não houve diferença entre PB em GMD. As diferenças entre PB em matéria de eficiência também foram eliminados durante a fase de terminação. Nosso estudo mostra que os animais mestiços têm, não só um maior desempenho, mas também apresentam melhores características de carcaça em relação ao Nelore, representando uma opção para aumentar a produtividade. Nós também acreditamos que seja possível ajustar as dietas de acordo com a fase de confinamento. Durante a fase de crescimento, 12% da PB deve ser usado, sendo reduzido para 10% durante a fase de terminação do confinamento, sem afetar o desempenho ou as características de carcaça. Um segundo experimento teve como objetivo avaliar as exigências de aminoácidos para bovinos de corte. Espera-se poder trabalhar com exigência de AA e não de PB, a fim de proporcionar a quantidade correta de AA essenciais para satisfazer os requisitos de mantenã e de produção. Apesar dos avanços na determinação de síntese de proteína microbiana edigestibilidade dos AA no intestino delgado (Rutherfurd et al., 2016), os avanços menores foram feitas no metabolismo intermediário de AA e especialmente em exigências líquidas de AAs (Tedeschi et al., 2015). Além disso, a utilização de animais cruzados tem sido cada vez mais, no entanto, não há dados na literatura comparando requisitos AAs entre GG, ou correlacionando a eficiência com as exigências de aminoácidos. Portanto, o objetivo deste estudo foi avaliar a proporção e a retenção dos AA na carcaça, bem como determinar as exigências líquidas de AA em touros Nelore e cruzados A × N, alimentado com dietas contendo diferentes níveis de proteína. Cinquenta e dois touros, (26 Nelore e 26 mestiças F1 Angus x Nelore), com 8 meses e peso corporal em jejum (PCj) inicial = 215,0 ± 15,0 kg (Nelore = 208,0 ± 12,78 kg; Angus x Nelore = 221,9 ± 14,16 kg) foram utilizados neste experimento. Oito animais (4 de cada grupo genético) foram abatidos no início do experimento, e utilizados como base de referência para estimar a composição química corporal inicial. Os 36 touros restantes foram distribuídos aleatoriamente a um dos três tratamentos. O experimento foi conduzido em delineamento inteiramente casualizado, com seis repetições, em esquema fatorial 2x3. Os fatores foram dois grupos genéticos (Nelore e cruzados F1 Angus x Nelore - A × N) e três teores de proteína bruta (PB) (100, 120 e 140 g / kg MS). O período experimental foi de 224 dias. Ao final do experimento, todos os animais foram abatidos para avaliar sua composição corporal de aminoácidos e as exigências líquidas de aminoácidos para ganho. No presente estudo, observa-se que alguns AA como lisina e fenilalanina tem alta correlação com o músculo, no entanto, outros aminoácidos (por exemplo, metionina) têm uma forte correlação com a composição do corpo. Vale ressaltar que este comportamento não é constante entre os diferentes pesos, mostrando que mais estudos como este precisam ser realizados para determinar com maior precisão as necessidades líquidas de aminoácidos para bovinos de corte. Um terceiro experimento foi conduzido com o objetivo de avaliar as exigências nutricionais de proteína e energia para mantença e ganho de peso e as eficiências de utilização da energia metabolizável para mantença e ganho de peso, usando a técnica do abate comparativo, e, ainda, estimar as exigências líquidas de energia para mantença utilizando-se a produção de calor mensurada em câmara respirométrica. Para avaliação da exigência pelo método do abate comparativo, foram utilizados 52 bovinos machos, não castrados, comida de média de 8 meses e peso médio inicial de 215,0±15,08 kg (Nelore = 208,0±12,78 kg; F1 Angus x Nelore = 221,9±14,16 kg). O experimento foi conduzido em delineamento inteiramente casualizado com seis repetições, em esquema fatorial 2x3. Os fatores foram dois grupos genéticos (Nelore e cruzado F1 Angus × Nelore - A × N) e três conteúdos de proteína bruta (PB) (100, 120 e 140 g/kg MS). Os animais selecionados para consumo voluntário foram redistribuídos aleatoriamente em três grupos que receberam uma das 3 dietas experimentais. Os animais em manteça foram alimentados com 12g de MS por kg de peso corporal, com a dieta de 12% de PB na base da MS. Os animais designados ao grupo referência foram abatidos para avaliação do peso PCVZ inicial e da composição química inicial do PCVZ. Ao final de 225 dias os animais foram abatidos.Para a avaliação em câmara respiromética,oito animais (4 Nelores e 4 cruzados Angus × Nelore) foram enviados para a Universidade Federal de Minas Gerais, onde, a produção de calor (PC) e de metano foram mensuradas. Logo após, esses mesmos 8 animais voltaram para a UFV, onde um experimento de digestibilidade foi conduzido utilizando um QL 4 × 4. A relação entre PCJ e o PCVZ encontrada neste estudo foi de 0,925. Houve diferença (P < 0,05) entre GG para a relação GMD x GPCVZ, sendo obtida a relação média de 0,966 para animais Nelore, e 0,947 para animais cruzados. O valor encontrado para Elm foi de 74,6 Kcal/PCVZ0,75/dia, não havendo diferença entre os GG. A EMm encontrada para animais Nelore foi de 122 kcal/PCVZ0,75/dia e de 119 kcal/PCVZ0,75/dia para animais cruzados. Não houve diferença entre os GG (P > 0,05) para ELg, sendo obtida a equação: ER = 0,0643 x PCVZ0,75 x GPCVZ0,6191. As eficiências de conversão da ELm para EMm de animais Nelore e cruzados neste experimento foram, respectivamente, 61,1 e 62,7%. A equação obtida para estimar a exigência líquida de proteína para ganho foi: PR = 188,37 x GPCVZ – 9,39 x ER. A eficiência de utilização da proteína metabolizável para ganho (k) foi de 0,3302. No experimento 2, as digestibilidades aparentes dos nutrientes não diferiram (P> 0,05) entre os GG. Da mesma forma, não houve diferença para as digestibilidades aparentes dos nutrientes (P> 0,05) quando se comparou consumo restrito e voluntário. O CPB aumentou linearmente (P< 0,05) com os níveis de PB. Houve efeito linear dos níveis dietéticos de PB (P< 0,05) sobre as digestibilidades aparentes da MS e MO. Uma Elmde 85,2 kcal/PCVZ0,75/dia e uma EMm de 114 kcal/PCVZ0,75/dia foram obtidas com a utilização da câmara respirométrica, sendo esses valores superior e inferior, respectivamente, aos obtidos pelo abate comparativo.
An experiment was conducted to evaluate whether a reduction in dietary crude protein and genetic group (GG) affects animal performance, feed efficiency and carcass traits of beef cattle at different stages of feedlot. Forty-four animals (22 Nellore and 22 crossbred F1 Angus x Nellore), with 8 months and initial shrunk BW (SBW) = 218.6 ± 2.15 kg (Nellore = 211.5 kg; Angus x Nellore = 225.7 kg) were used in this experiment. Eight animals (4 from each genetic group) slaughtered at the beginning of the experiment were used as baseline reference to estimate initial chemical body composition. The 36 remaining bulls were randomly assigned to one of three dietary treatments. The experiment was conducted in a completely randomized design with six replicates, in a 2x3 factorial scheme. The factors were two genetic groups (Nellore and crossbred F1 Angus x Nellore - A×N) and three crude protein contents (CP) (100, 120 and 140 g/kg DM).The experimental period lasted 224 days, being divided in 2 growing stages (GS; Growing (GR) = 112 days, and Finishing (FS) = 112 days). At the end of the experiment, all animals were slaughtered to evaluate their chemical body composition, and carcass characteristics. Crossbred A×N had a higher DMI (%BW) (19.28) compared to Nellore (18.26), and also higher ADG (A×N = 1.18; Nellore = 0.88 kg/d), regardless of growth stage or CP. Crossbred A×N had a higher intake of all nutrients regardless theCPor growth stage. Crossbred A×N ended up the experiment heavier than Nellore, since they showed a greater ADG and were more efficient when compared to Nellore animals. DMI did not differ (P> 0.05) among CP contents within growth stages, however it increased over time. Animals fed 14% CP had a lower DMI (g/BW) during growing stage, however differences were vanished on finishing stage. During growing stage, animals fed 10% CP had a lower ADG compared with animals fed 12 and 14% CP, which did not differ between them. However, during finishing stage there was no difference among CP on ADG. Differences among CP regarding efficiency were also eliminated during finishing stage. Our study found that crossbred animals have, not only greater performance, but also show better carcass traits compared to Nellore, representing an option to increase productivity. We also found that it is possible to adjust diets according to feedlot stage. During the growing stage, 12% of CP should be used, being reduced to 10% during finishing stage of feedlot, without adversely affects performance or carcass characteristics. A second trial aimed to evaluate amino acids requirements for beef cattle. It is expected to work with AA instead of CP requirements in order to provide the correct amount of essential AA to meet maintenance and production requirements. Despite the advances in determining microbial protein synthesis and AA digestibility in small intestine (Rutherfurd et al., 2016), lesser advances were done in intermediate metabolism of AA and especially in net requirements of AAs (Tedeschi et al., 2015). Furthermore, the use of crossbred animals has been increasingly, however, there is no data in the literature comparing AAs requirements between GG, or correlating efficiency with amino acids requirements. Therefore, the objective of this study was to evaluate the retention of AA in the empty body weight and also to determine net requirements of AA in purebred (Nellore) and crossbred (A×N) bulls, fed different crude protein content. Fifty-two bulls, (26 Nellore and 26 crossbred F1 Angus x Nellore) with 8 months and initial shrunk BW (SBW) = 215.0 ± 15.0 kg (Nellore = 208.0±12.78 kg; Angus x Nellore = 221.9±14.16 kg) were used in this experiment. Eight animals (4 from each genetic group) slaughtered at the beginning of the experiment were used as baseline reference to estimate initial chemical body composition. The 36 remaining bulls were randomly assigned to one of three dietary treatments. The experiment was conducted in a completely randomized design with six replicates, in a 2x3 factorial scheme. The factors were two genetic groups (Nellore and crossbred F1 Angus x Nellore - A×N) and three crude protein contents (CP) (100,120 and 140 g/kg DM).The experimental period lasted 224 days. At the end of the experiment, all animals were slaughtered to evaluate their amino acid composition in the body and also the net requirements of amino acids for gain. In the present study it is observed that some AA as lysine and phenylalanine have high correlation with muscle, however, other amino acids (e.g. methionine) have a stronger correlation with body’s composition. It is worth mentioning that this behavior is not constant among different weights, showing that more studies like this need to be conducted to determine more precisely the net requirements of amino acids.A third experiment was divided in two trials. The objective of the first trial was to the nutritional requirements of protein and energy for maintenance and weight gain and the efficiencies of use of metabolizable energy for maintenance and weight gain using the comparative slaughter technique. In the second trial, the net energy requirements for maintenance were also estimated using the heat production measured in a respirometric chamber. In trial 1, 52 animals (26 Nellore and 25 Angus × Nellore), with 8 months and initial body weight = 215.0 ± 15.08 kg (Nellore = 208.0 ± 12.78 kg; F1 Angus x Nellore = 221.9 ± 14.16 kg). The experiment was conducted in a completely randomized design with six replicates, in a 2×3 factorial scheme. The factors were two genetic groups (Nellore and cross-breed F1 Angus × Nellore - A × N) and three crude protein contents (CP, 100, 120 and 140 g / kg DM). The animals selected for voluntary consumption were randomly assigned to one of three dietary treatments. The animals in maintenance were fed with 12g DM/kg BW, with the diet of 12% CP on the DM basis. The animals assigned to the reference group were slaughtered for evaluation of initial empty body weight (EBW) and initial chemical composition of EBW. At the end of 225 days the animals were slaughtered. Trial 2 was carried out at the Federal University of Minas Gerais, where the production of heat (PC) and methane from eight animals (4 Nellor and 4 Crusaders Angus × Nellore) were measured in a respirometric chamber. Soon after, these same animals returned to the UFV, where a digestibility experiment was conducted using a 4 × 4 Latin Square. The relationship between SBW and EBW found in this study was 0.925. There was a difference (P <0.05) between GG for the ADG x EBWG ratio, with an average ratio of 0.966 for Nellore animals and 0.947 for crossbred animals. The value found for NEm was 74.6 Kcal / PCVZ0.75 / day, with no difference between the GGs. The MEm found for Nellore animals was 122 kcal / EBW0.75 / day and 119 kcal / EBW0.75 / day for crossbred animals. There was no difference between GG (P> 0.05) for NEg, and the equation was: RE = 0.0643 x EBW0.75 x EBWG0.6191. The conversion efficiencies of NEm to MEm of Nellore and crossbred animals in this experiment were, respectively, 61.1 and 62.7%. The equation obtained to estimate the net protein requirement for gain was: RP = 188.37 x EBWG - 9.39 x RE. The efficiency of use of the metabolizable protein for gain (k) was 0.3302. In trial 2, apparent digestibilities of nutrients did not differ (P> 0.05) among GG. Likewise, there was no difference for apparent digestibilities of nutrients (P> 0.05) when comparing restricted and voluntary consumption. CPI increased linearly (P <0.05) with CP levels. There was a linear effect of dietary levels of CP (P <0.05) on the apparent digestibilities of DM and OM. An NEm of 85.2 kcal / EBW0.75 / day and an MEm of 114 kcal / EBW0.75 / day were obtained using the respirometric chamber, these values being higher and lower, respectively, than those obtained by the comparative slaughter.

ultimi decenni i consumatori sono sempre più attenti all’alimentazione, scegliendo prodotti di nicchia come quelli biologici o prodotti che non prevedono l’utilizzo di OGM nella dieta degli animali, ponendo particolare attenzione al benessere animale. Relativamente al benessere animale, il microbiota intestinale svolge un ruolo chiave nella fisiologia dell’animale, ed è ormai acclarato che assicurare la salute intestinale è la chiave per garantire la salute e il benessere dell’animale. Negli ultimi anni, la tecnologia di iniezione in ovo ha permesso la somministrazione di probiotici, prebiotici e simbiotici, all’embrione in una fase iniziale di sviluppo, influenzando il microbiota nei pulcini appena nati, consentendo una maggiore protezione contro il rischio di infezioni gastrointestinali e il miglioramento delle prestazioni produttive e delle caratteristiche qualitative della carne dei polli trattati. Lo scopo della presente tesi è stato duplice: a) studiare gli effetti dell’iniezione in ovo di un prebiotico commerciale (galatto-oligosaccaridi, GOS) sulle performance e sulla qualità della carne in polli a lenta crescita esposti a stress da calore; b) valutare le caratteristiche qualitative della carne di polli di due diverse linee produttive dell’azienda Amadori, linea Vegetale® e linea Campese®, costituite rispettivamente da ibridi commerciali a rapido accrescimento, allevati con tecniche intensive, e da ibridi a lenta crescita, allevati semi-estensivamente, entrambi alimentati con una dieta a base vegetale senza OGM. La valutazione è stata effettuata considerando il genotipo, sesso ed età di macellazione. Per il primo studio sono stati utilizzati polli maschi (Hubbard RedBro x Hubbard JA57). Al 12° giorno di incubazione, dopo la speratura, 3.000 uova con embrioni vitali sono state divise casualmente in 3 gruppi sperimentali: gruppo prebiotico (GOS) iniettato con una singola dose di 3,5 mg di GOS/uovo in 0,2 mL di soluzione fisiologica; gruppo salino (S) iniettato con 0,2 mL di soluzione fisiologica (0,9% NaCl); gruppo di controllo (C) non iniettato. Dopo la schiusa, 900 pulcini maschi (300 pulcini/trattamento) sono stati allevati in recinti a terra in condizioni termoneutrali (TN; 6 box/gruppo, 25 animali/box) o in condizioni di stress termico (HS, 30°C da 36 a 50 giorni; 6 box/gruppo, 25 animali/box). Sono state registrate le performance in vivo (peso vivo e assunzione di cibo per box, mortalità) e calcolato l’indice di conversione alimentare. A 50 giorni, tra tutti i polli macellati sono state scelte random e pesate 15 carcasse/trattamento/temperatura. Da ogni carcassa è stato prelevato il muscolo pettorale e pesato, le analisi chimico-fisiche sono state effettuate sul muscolo pettorale. Il GOS ha avuto un lieve effetto sulle prestazioni in vivo e sulla qualità della carne nei polli esposti a stress da calore. Lo stress da calore ha avuto un effetto negativo sulle prestazioni di crescita degli animali. Tuttavia, considerando che si tratta del primo studio effettuato con il suddetto genotipo, sono necessarie ulteriori indagini per comprendere meglio l’attività del prebiotico sul metabolismo animale. Nella seconda parte della tesi sono state studiate le caratteristiche qualitative della carne (muscolo pettorale) di ibridi commerciali a crescita lenta di sesso diverso (Prova 1, Red 75-Campese®), e a crescita lenta (Prova 2, Red 75-Campese®) e rapida (Prova 3, Ross 308-Vegetale®) di diverse età di macellazione. I risultati hanno evidenziato che la carne della linea Campese® e Vegetale®, pur essendo differente dal punto di vista chimico-fisico e nutrizionale tra maschi e femmine e tra animali di età diverse, è risultata di buona qualità rispecchiando i dati riportati in letteratura.
In recent decades, the consumers have become more health conscious paying more attention to nutrition and health claims, choosing niche products such as organic or products that do not include the use of GMOs in animal’s diet, paying particular attention to animal welfare. Regarding animal welfare, the intestinal microbiota plays a key role in the physiology of the animal. In recent years, in ovo technology has enabled the administration of probiotics, prebiotics and synbiotics to the embryo at an early stage of development, influencing the structure of microbiota in newly hatched chicks, allowing a greater protection against the risk of gastrointestinal infections, and improving productive performance and meat quality traits of treated chickens. The aim of this thesis was twofold: a) to study the effects of commercial prebiotic’s (galactooligosaccharides, GOS) in ovo injected on performance and meat quality in slow-growing chickens exposed to heat stress; b) evaluate the chickens’ meat qualitative characteristics from two different production lines of the Amadori company, Vegetale® and Campese® lines, respectively consisting of fast-growing commercial hybrids reared with intensive techniques, and slow-growing hybrids reared semi-extensively, both fed with a plant-based diet without GMOs. The evaluation was carried out through considering different factors, such as genotype, sex and slaughter age. Male chickens (Hubbard RedBro x Hubbard JA57) were used for the first study. On the 12th day of incubation, after candling, 3.000 eggs with viable embryos were randomly divided into 3 experimental groups: prebiotic group (GOS) injected with a single dose of 3.5 mg of GOS/egg in 0.2 mL of physiological solution; saline group (S) injected with 0.2 mL of physiological solution (0.9% NaCl); control group (C) not injected. After hatching, 900 male chicks (300 chicks/treatment) were reared in free-range pens under thermoneutral conditions (TN; 6 pens/group, 25 birds/pen) or under heat stress conditions (HS, 30 °C from 36 at 50 days; 6 pens/group, 25 birds/pen). In vivo performances (live weight and food intake per box, mortality) were recorded, and the food conversion ratio calculated. At 50 days, 15 carcasses/treatment/temperature were randomly selected and weighed from all slaughtered chickens. The pectoral muscle was taken from each carcass and weighted, the physico-chemical analyses were carried out on the pectoral muscle. In ovo injection with GOS has a mild effect on in vivo performance and meat quality in slow-growing broilers exposed to heat stress. As expected, thermal challenge applied for the last 14 days of finisher feeding phase, had a dampening effect on growth performance. However, considering that it is the first study carried out with the aforementioned genotype, further investigations are necessary to better understand the activity of these substances on animal metabolism. In the second part of the thesis, the meat qualitative characteristics (pectoral muscle) of slow-growing commercial hybrids of different sexes (Test 1, Red 75-Campese®), and slow-growing (Test 2, Red 75-Campese®) and fast-growing (Test 3, Ross 308-Vegetale®) of different slaughter ages was assessed. The results showed that the meat of both Campese® and Vegetale® line, despite being different from a physico-chemical and nutritional point of view between males and females and between animals of different ages, was of good quality, reflecting the data reported in literature.

Three-phase power transformers continue to be an important fixture in modern power systems since their initial development in the 1880s. While transformer design has fundamentally remained the same, the operating environment has significantly changed. This is apparent through new flexible network operations (e.g., integration of renewable energy sources), growing network complexities (e.g., deployment of micro-grids, smart grids, etc.) and increasing use of nonlinear power electronic equipment (e.g., power converters and motor drives). Thus the issue of power quality in power systems has become an important consideration to utilities and industries as the performance of electrical machines and devices could be adversely affected. This doctoral thesis focuses on the performance of three-phase power transformers under various nonlinear and dynamic electromagnetic disturbances in distorted power networks.The first part of this work is devoted to the development and improvement of nonlinear electromagnetic models of three-phase multi-leg transformer cores for the study of steady-state and transient electromagnetic disturbances. This is mainly achieved by developing new detailed magnetic models for ferromagnetic nonlinearities (e.g., hysteresis) as well as considering core asymmetry and magnetic couplings of core-leg fluxes in three-phase multi-leg iron-core structures. These combined effects have not been considered in conventional electromagnetic transient studies of transformers and are shown in this work for the first time to have a significant impact on predicted steady-state and transient electromagnetic behaviour.In subsequent parts of this thesis, the developed models are applied to the examination of selected nonlinear electromagnetic phenomena such as transformer operation in harmonically distorted power systems (e.g., terminal voltage distortions and nonlinear loads), dc bias caused by geomagnetically induced currents, ferroresonance, and no-load magnetisation and inrush current effects. Furthermore, based on the new modelling approaches, improved methods are presented for estimating transformer aging with wider applicability to three-phase transformers considering load and source imbalances with harmonic distortions.With the advent of newly emerging smart grids, the last part of this thesis is devoted to exploring future transformer operation in new smart grid operating conditions such as plug-in electric vehicle charging. Transformer loading patterns with random uncoordinated PEV charging compared to coordinated charging activity in smart grids is investigated. The investigation highlights the notion of harnessing future smart grid technologies to better manage transformer health and performance.

Pig industry is required to reduce its environmental footprint, in order to satisfy the increasing demand of eco-friendly products. Moreover, the producers need to cut down with the feeding costs, by improving the pigs’ feed efficiency. Despite the rich literature, knowledge about the effect of some feeding strategies on feeding behaviour, performance, and quality of meat and meat products seems still controversial or scarce. With this background, the aims of this Ph.D. project were: i) to assess the influence of a reduction in dietary indispensable amino acids (AA) on feed intake, growth performance, N excretion and carcass and meat quality traits of fast growing pigs fed according to an ad libitum or a restricted feeding regime; ii) to study the feeding behaviour of group-housed pigs fed individually from single-space feeders and subjected to feed restriction and a reduction in the dietary indispensable AA content; iii) to explore the influence of feeding behaviour on growth performance, carcass and meat characteristics of pigs; iv) to investigate the influence of low-protein and AA diets on the characteristics of San Daniele like dry-cured hams obtained from two genetic groups of pigs with different lean growth potential. In the 1st Chapter, 96 barrows were individually fed through automatic feeding stations, according to an ad libitum or restricted feeding regime and to a conventional or low-AA diet. Feed restriction decreased feed intake, average daily gain, carcass weight, backfat depth, but increased gain:feed ratio. The low-AA diets increased feed intake, carcass weight and the intramuscular fat content, with no effects on the feed efficiency and the estimated Pr. Nitrogen excretion was reduced by feed restriction and by the reduction of the dietary AA content. In the 2nd Chapter, the data recorded by the automatic feeding stations were used to study the effects of the feeding regime and the dietary AA restriction on the feeding patterns of the pigs of the previous contribution. Feed restriction decreased daily feed intake, the number of visits and the time spent feeding, but increased feed consumption per visit and feeding rate. The low-AA diets increased daily feed intake, tended to increase feeding rate and interacted with feeding regime for the number and duration of feeding visits. The pigs were able to adapt their feeding patterns to compensate for a reduction in feed allowance or nutrient restriction. In the 3rd Chapter the phenotypic correlations among feeding patterns, growth performances and carcass traits were studied. The records of each pig were classified into feeding rate tertiles. Pigs eating faster showed greater final body weights, average daily gains, estimated protein gains, estimated lipid retention, carcass weights, weights of lean cuts, weights of fat cuts, proportions of fat in the carcass, and lower proportions of carcass lean cuts than pigs eating slowly. Manipulating the eating rate, through management or genetic strategies, could affect growth performances and carcass quality, with little influence on feed efficiency. The 4th Chapter investigated the influence of diets lowered in protein and AA contents on the quality of 40 San Daniele like dry-cured hams produced by pigs of two genetic groups (Danbred and Anas) characterized by different potential for lean growth, eating conventional or low-protein diets. The Danbred fresh hams were heavier, but showed greater seasoning losses and thinner fat cover than Anas hams. Dry-cured hams from Danbred had higher protein content than the Anas ones. Dietary protein restriction had small influence on dry-cured ham quality. Due to its positive effects on sustainability of dry-cured ham chain by decreasing pig farm nitrogen excretion and feeding costs, the use of low-protein diets seems an advisable strategy for the feeding of traditional PDO heavy pigs.
Il settore suinicolo deve oggi soddisfare la domanda di prodotti eco-friendly, ridurre i costi di produzione e migliorare l’efficienza alimentare dei maiali attraverso l’utilizzo di nuove strategie alimentari. Gli obiettivi di questo progetto di dottorato sono: i) valutare l’influenza di una riduzione del contenuto di amminoacidi della dieta su consumo alimentare, prestazioni e qulità della carne di maiali alimentati secondo un regime alimentare ad libitum o razionato; ii) studiare il comportamento alimentare dei maiali sottoposti ad una restrizione alimentare e ad una riduzione del contenuto di amminoacidi essenziali dell’alimento; iii) conoscere l’influenza del comportamento alimentare sulle prestazioni e le caratteristiche della carcassa; iv) esaminare gli effetti di una riduzione del contenuto di proteina e amminoacidi sulla qualità di prosciutti crudi ottenuti da due linee genetiche caratterizzate da diversi potenziali di crescita magra e stagionati come prosciutti San Daniele DOP. Nel I contributo, 96 maiali sono stati alimentati attraverso un regime alimentare ad libitum o una leggera restrizione alimentare utilizzando diete convenzionali o con basso contenuto di amminoacidi essenziali (LAA). La restrizione alimentare ha ridotto i consumi di alimento, gli accrescimenti, i pesi delle carcasse e gli spessori del grasso, ma ha aumentato l’efficienza alimentare. La dieta LAA ha aumentato i consumi, i pesi e il contenuto di grasso delle carcasse, senza influenzare l’efficienza alimentare e la crescita proteica. I due trattamenti alimentari hanno ridotto l’escrezione di azoto. Nel II contributo, si sono valutati gli effetti del regime alimentare e della dieta LAA sul comportamento alimentare dei maiali. La restrizione alimentare ha ridotto l’ingestione di alimento, il numero di visite alla mangiatoia e il tempo utilizzato per mangiare, ma ha aumentato il consumo per visita, e la velocità d’ingestione. La dieta LAA ha aumentato i consumi alimentari, e ha provocato un leggero aumento della velocità d’ingestione. I maiali sono stati in grado di adattare il loro comportamento alimentare per superare i limiti dovuti alla restrizione alimentare e alla riduzione di nutrienti del mangime. Nel III capitolo, si sono studiate le relazioni tra comportamento alimentare, prestazioni e caratteristiche della carcassa. I dati di ciascun maiale sono stati classificati secondo tre classi di velocità d’ingestione. I maiali che mangiavano più rapidamente avevano maggiori pesi, accrescimenti proteici e lipidici, pesi delle carcasse, dei tagli magri e dei tagli grassi, con una più elevata proporzione di tagli grassi, rispetto ai maiali più lenti. Manipolare il comportamento alimentare attraverso strategie manageriali e alimentari può avere effetti favorevoli sulle prestazioni produttive e la qualità della carcassa, senza alterare l’efficienza alimentare dei maiali. Nel IV capitolo della tesi si è valutato l’effetto di una riduzione del contenuto di proteina e amminoacidi essenziali della dieta sulle caratteristiche di qualità di 40 prosciutti crudi lavorati come prosciutti San Daniele DOP e ottenuti da due linee genetiche con un diverso potenziale per la crescita magra alimentate con diete convenzionali o a basso tenore proteico. Le cosce rifilate dei Danbred erano più pesanti, ma mostravano maggiori perdite di stagionatura e minori spessori del grasso di copertura rispetto a quelle ottenute degli Anas. Inoltre, i prosciutti dei Danbred hanno avuto un maggior contenuto di proteina. Invece, la riduzione del contenuto proteico e amminoacidico della dieta ha influenzato poco le caratteristiche di qualità dei prosciutti crudi. Dunque, dati gli effetti favorevoli alla riduzione delle escrezioni di azoto e dei costi di alimentazione, l’uso di diete a basso tenore proteico può essere un’efficace soluzione per l’alimentazione del suino pesante italiano.

The rapid advances in technology and increase of tech investments across all the industries have promoted the emergence of several startups. Unfortunately, not all startups succeed despite of having good initial ideas. One reason to the poor business performance could be a lack of managerial control. Researchers and industry experts believe that performance management could support tech entrepreneurs to monitor and control the drivers that promote growth and their success. However, there is a lack of studies that could support these thoughts about its suitability for tech startups. Therefore, this study gathers empirical findings from Swedish tech startups as well as industry experts to discuss this issue. The findings show that a performance measurement system such as the Balanced Scorecard is a suitable practice for tech entrepreneurs. It also brings some insights about how the performance measurements evolve as the firms mature.

Includes bibliographical references (leaves 53-55).
The major research behind this written explication was the creation of a play about tea-cups and doing the washing. This production was devised, directed, designed and written with several UCT drama students, other selected performers and musicians and played at The Little Theatre, Orange St, Cape Town, in October 2004. I wanted to make a piece of 'home - grown' theatre, a term I have developed to describe a primarily visual art-form that focuses on recognising beauty in everyday existence. Home-grown theatre is concerned with the profound importance of very commonplace things and the complexity and density contained within this mundane terrain. This paper explains the concepts and principles that surround home-grown theatre to provide a context for the thinking and the motivation behind it. This paper explicates both the theory that informed my ideas for its conception and the philosophies of art and science that inspired my style for making the play. It investigates the work and writings of artists, philosophers, scientists, playwrights and theatre practitioners, who all identify elements in their fields, which link them to my home-grown theatre.

The aim of this study was to evaluate plant growth, grain yield and symbiotic N contribution by 32 cowpea genotypes, at Taung in South Africa. The data from a 2-year field study conducted in 2005 and 2006 showed that genotypes Fahari, Pan 311 and Glenda exhibited the highest dry matter yield and N contribution as they produced 2.9-, 2.7- and 3.5-fold more dry matter than cv. ITH98-46 and yielded 2.7-, 2.2- and 3.2-fold more N than cultivar ITH98-46 from IITA. Except for Benpila, all the 32 cowpea genotypes derived between 52.0 and 80.9% of their N nutrition from symbiotic fixation in 2005, with IT82D-889, Botswana White, IT93K-2045-29 and Ngonji exhibiting the highest %Ndfa values. The genotype Fahari showed the highest amount N-fixed (182 kg N-fixed/ha), followed by Pan 311, Glenda, TVu11424 and Mamlaka which contributed 160, 146, 130 and 125 kg N/ha, respectively. Genotypes Pan 311, Fahari and Glenda were among those that produced highest grain yield in 2005 and except for CH14 and IT86S-2246 (which produced 131 kg N/ha each), Fahari, Glenda and Pan 311, were again the highest in symbiotic N contribution (112, 106 and 105 kg N/ha, respectively). Grain yield was similarly high in Glenda, Pan 311 and Fahari (3.3, 3.1 and 2.9 t/ha, respectively) in 2006. In general, these data show that genotypes that fixed more N also produced more biomass and grain yield and are therefore, the best candidates for inclusion in cropping systems as biofertilizers.

Abstract The aim of this study was to evaluate plant growth, grain yield and symbiotic N contribution by 32 cowpea genotypes, at Taung in South Africa. The data from a 2-year field study conducted in 2005 and 2006 showed that genotypes Fahari, Pan 311 and Glenda exhibited the highest dry matter yield and N contribution as they produced 2.9-, 2.7- and 3.5-fold more dry matter than cv. ITH98-46 and yielded 2.7-, 2.2- and 3.2-fold more N than cultivar ITH98-46 from IITA. Except for Benpila, all the 32 cowpea genotypes derived between 52.0 and 80.9% of their N nutrition from symbiotic fixation in 2005, with IT82D-889, Botswana White, IT93K-2045-29 and Ngonji exhibiting the highest %Ndfa values. The genotype Fahari showed the highest amount N-fixed (182 kg N-fixed/ha), followed by Pan 311, Glenda, TVu11424 and Mamlaka which contributed 160, 146, 130 and 125 kg N/ha, respectively. Genotypes Pan 311, Fahari and Glenda were among those that produced highest grain yield in 2005 and except for CH14 and IT86S-2246 (which produced 131 kg N/ha each), Fahari, Glenda and Pan 311, were again the highest in symbiotic N contribution (112, 106 and 105 kg N/ha, respectively). Grain yield was similarly high in Glenda, Pan 311 and Fahari (3.3, 3.1 and 2.9 t/ha, respectively) in 2006. In general, these data show that genotypes that fixed more N also produced more biomass and grain yield and are therefore, the best candidates for inclusion in cropping systems as biofertilizers.

Thesis (PhD(Agric))--Stellenbosch University, 2013.
ENGLISH ABSTRACT: The development and application of science-based tools for determining optimum fruit maturity and postharvest handling protocols to maintain quality and reduce losses during postharvest handling and marketing is essential to maintain the competitiveness of the emerging pomegranate industry in South Africa. Currently, there are no quality standards for the South African pomegranate industry, neither is there a general consensus on the optimal harvest maturity indices for fruit cultivars. These information are important to ensure the delivery of good quality fruit to consumers, particularly for long supply chains. The overall aims of this study were (a) to develop science-based management tools for determining optimum maturity indices and storage performance of pomegranate fruit cultivars grown in South Africa, and (b) to characterise the physico-chemical and pharmacological properties of selected cultivars relevant to postharvest handling and industrial applications. In Section II, seasonal studies on pomegranate (‘Baghwa’ and ‘Ruby’) fruit growth and the evolution of maturity indices during development were conducted. Significant increases in total soluble solids (TSS), sugars (glucose and fructose) and anthocyanin composition, coupled with significant decline in titratable acidity (TA), organic acids and total phenolics (TP) occurred with advancing fruit maturity. Fruit at advanced maturity stages were characterized by intense pigmentation of peel and aril, which coincided with maximum accumulation of anthocyanins. Among all the major maturity indices investigated, TSS, BrimA and anthocyanins did not show significant (p<0.05) seasonal variability, and strong correlations were found among the indices. In combination, these indices accounted for fruit juice sugar content, acidity and colour and could serve as reliable markers to determine optimal maturity for both pomegranate cultivars. The studies in Section III focused on characterization of postharvest quality including nutritional, medicinal and antioxidant properties of fruit parts. Quality attributes of eight commercial cultivars were analysed by cluster analysis, which enabled the cultivars to be separated into two clusters (cluster 1 = ‘Ruby’, ‘Arakta’ and ‘Ganesh’; cluster 2 = ‘Bhagwa’, ‘Acco’ and ‘Herskawitz’) and two ungrouped cultivars (‘Molla de Elche’ and ‘Wonderful’) based on important quality attributes (size, texture, colour, soluble solids, acidity, juiciness and phenolics). Furthermore, pomegranate fruit peel extracts were studied to highlight their potential for value-adding in pharmaceutical and other industrial applications. The results showed that fruit peels of the investigated cultivars possess strong antibacterial, antioxidant and antityrosinase activities, and hence could be exploited as potential sources of natural antimicrobial and antioxidant agents, as well as a potential tyrosinase inhibitor. The research reported in Section IV investigated the effects of harvest maturity and storage conditions on postharvest quality and nutritional value of ‘Bhagwa’ and ‘Ruby’ cultivars. Fruit harvested at commercial maturity were stored at 5±0.3°C, 7±0.5°C and 10±0.4°C with 92±3% RH and at room temperature (20±2.2°C, 65±5.5% RH) for 16 weeks. Fruit physiological responses and quality were affected by storage condition, with the maximum levels of respiration occurring at higher temperature and extended storage duration. Fruit colour and antioxidant capacity varied slightly among storage temperatures, with total soluble solids and titratable acidity decreasing gradually over time at different temperatures. Considering that fruit stored at 5°C and 92% RH had significantly reduced weight loss, low incidence of physiological disorders and best results in maintaining flavour attributes (TSS and TA, TSS:TA ratio), the investigated cultivars may be stored at 5°C and >92% RH for 8 - 12 weeks. In paper 9 (Section IV), the research investigated the relationships between instrumental and sensory measurements of pomegranate fruit at different harvest maturities during storage and shelf life. Mature ‘Bhagwa’ fruit harvested at different times could not be discriminated by sensory attributes assessed by a trained panel. However, TSS (R2 = 0.677) and juice content (R2 = 0.512) were the two most decisive quality attributes at shelf life related to harvest maturity status. For ‘Ruby’, however, a combination of instrumental and sensory attributes appeared to be influential in discriminating mature fruit harvested at different times, with TSS:TA ratio being the most decisive (R2 = 0.654) in distinguishing different fruit harvests, followed by sweet taste (R2 = 0.474) and hue angle (R2 = 0.431). The results showed that to ensure the best post-storage quality of ‘Bhagwa’, the optimum harvest maturity was between 167 - 175 DAFB (H2 and H3) when fruit reached maximum TSS level (>16°Brix; H3) and juice content (>65 mL/100 g aril; H2). However, for ‘Ruby’, this study indicated that the optimum harvest date was at 143 DAFB (H2) when TSS:TA ratio was >55, which coincided with significantly higher sensory rating for sweet taste after shelf life of fruit at H2 than H1 and H3, respectively. The results from this thesis provide new understanding and better insights on fruit characteristics of major pomegranate cultivars grown in South Africa. Overall, the study provides new knowledge on science-based tools for assessing fruit readiness for harvest as well as storage conditions to maintain fruit postharvest quality and reduce losses. It also provides scientific information on phytochemical contents and antioxidant compounds in fruit to promote value-adding of pomegranate as a good raw material with potential applications in health food products and other industrial applications such as pharmaceuticals and cosmetics.
AFRIKAANSE OPSOMMING; Die ontwikkeling en toepassing van wetenskapgegronde instrumente vir die bepaling van optimale vrugrypheid en naoes-hanteringsprotokolle om gedurende die naoes-hantering en -bemarking van vrugte gehalte te behou en verliese te verminder, is noodsaaklik om die mededingendheid van die ontluikende granaatbedryf in Suid-Afrika te verseker. Tans is daar nie enige gehaltestandaarde vir die Suid-Afrikaanse granaatbedryf óf algemene eenstemmigheid oor die optimale oesrypheidsaanwysers vir vrugtekultivars nie. Hierdie inligting is belangrik om die naoes-lewering van uithalervrugte aan verbruikers te verseker, veral vir lang verskaffingskettings. Die oorkoepelende doelwitte van hierdie studie was (a) om wetenskapgegronde bestuursinstrumente te ontwikkel vir die vasstelling van optimale rypheidsaanwysers en bergingsprestasie van granaatkultivars wat in Suid-Afrika verbou word, en (b) om die fisiko-chemiese eienskappe en farmakologiese kenmerke van gekose kultivars te tipeer. In deel II is seisoenale studies oor granaatgroei en die ontwikkeling van rypheidsaanwysers gedurende groei onderneem. Namate vrugte ryp geword het, is beduidende toenames in totale oplosbare vaste stowwe (TSS), suikers (glukose en fruktose) en antosianien-samestelling opgemerk, sowel as ’n beduidende afname in titreerbare suur (TA), organiese suur en totale fenol (TP). Vrugte in gevorderde stadia van rypheid is gekenmerk deur intense pigmentasie van die skil en aril, wat met maksimum opbou van antosianien verband gehou het. Van ál die belangrike rypheidsaanwysers wat ondersoek is, het TSS, BrimA en antosianien onbeduidende (p<0.05) seisoenale veranderlikheid getoon, en is sterk verbande tussen die aanwysers opgemerk. Gesamentlik sou die aanwysers kon rekenskap gee van sapsuikerinhoud, -suurgehalte én -kleur, en sou dit dus as betroubare rypheidsmerkers kon dien om optimale rypheid vir albei granaatkultivars te bepaal. Die studies in deel III het gekonsentreer op die tipering van die naoes-kenmerke, onder meer die voedings-, medisinale en antioksidant-kenmerke van vrugtedele. Kenmerke van agt kommersiële kultivars is deur middel van groepsontleding bestudeer, waarvolgens die kultivars op grond van belangrike kenmerke (grootte, tekstuur, kleur, oplosbare vaste stowwe, suurgehalte, sappigheid en fenol) in twee groepe (groep 1 = ‘Ruby’, ‘Arakta’ en ‘Ganesh’; groep 2 = ‘Bhagwa’, ‘Acco’ en ‘Herskawitz’) en twee niegegroepeerde kultivars (‘Molla de Elche’ en ‘Wonderful’) ingedeel is. Ten einde die toegevoegde waarde van granaatskille vir farmaseutiese en kosmetiese doeleindes te bevorder, is skilekstrakte ook bestudeer. Die resultate toon dat die vrugteskille van die bestudeerde kultivars oor sterk antibakteriese, antioksidant- en antitirosinase- eienskappe beskik. Daarom kan die skil van die granaatkultivars as moontlike bron van natuurlike antimikrobiese en antioksidant-agense sowel as ’n moontlike tirosinase-inhibitor ontgin word. Die navorsing in deel IV het ondersoek ingestel na die uitwerking van oesrypheid en bergingsomstandighede op die naoes-gehalte en -voedingswaarde van die kultivars ‘Bhagwa’ en ‘Ruby’. Vrugte wat op kommersiële rypheid geoes is, is vir 16 weke by 5±0.3 °C, 7±0.5 °C en 10±0.4 °C met 92±3% RH, sowel as by kamertemperatuur (20±2.2 °C, 65±5.5% RH) geberg. Die bergingsomstandighede het die fisiologiese reaksies en gehalte van die vrugte beïnvloed: Maksimum vlakke van respirasie het teen hoër temperature en met verlengde berging voorgekom. Die kleur en antioksidantvermoë van die vrugte het effens tussen bergingstemperature verskil, en totale oplosbare vaste stowwe en titreerbare suur het mettertyd geleidelik by verskillende temperature afgeneem. Gedagtig daaraan dat die vrugte wat teen 5 °C en 92% RH geberg is beduidend minder gewigsverlies, ’n lae voorkoms van fisiologiese afwykings en die beste resultate in blywende geurkenmerke (TSS en TA, TSS:TA-verhouding) getoon het, kan die bestudeerde kultivars vir 8 tot 12 weke teen 5 °C en >92% RH geberg word (navorsingstuk 8). In navorsingstuk 9 (deel IV) is daar ondersoek ingestel na die verhouding tussen instrument- en sintuiglike metings van granate in verskillende stadia van oesrypheid gedurende berging en raklewe. Geen verskil in sintuiglike kenmerke kon bespeur word by ryp ‘Bhagwa’- vrugte wat op verskillende tye geoes is nie. Tog was TSS (R2 = 0.677) en sapinhoud (R2 = 0.512) die twee bepalendste gehaltekenmerke wat betref oesrypheidstatus gedurende raklewe. By ‘Ruby’ kon ’n kombinasie van instrument- en sintuiglike kenmerke egter wél tussen stadia van oesrypheid onderskei, met die TSS:TA-verhouding die bepalendste (R2 = 0.654) in die onderskeid tussen verskillende vrugteoeste, gevolg deur ’n soet smaak (R2 = 0.474) en skakeringshoek (R2 = 0.431). Die resultate toon dat die beste nabergingsgehalte vir ‘Bhagwa’ verkry word by ’n optimale oesrypheid van 167–175 DAFB (H2 en H3), wanneer vrugte die maksimum TSS-vlak (>16°Brix; H3) en sapinhoud (>65 mL/100 g aril; H2) bereik het. Vir ‘Ruby’ dui hierdie studie op ’n optimale oesdatum van 143 DAFB (H2) met ’n TSS:TA-verhouding van >55, wat verband gehou het met ’n beduidend hoër telling vir soet smaak by H2 eerder as by H1 en H3 ná raklewe. Die resultate van hierdie tesis bied ’n beter begrip van, en insig in, die vrugtekenmerke van granaatkultivars wat in Suid-Afrika verbou word. Oor die algemeen bied die studie wetenskaplike inligting om moontlik die toegevoegde waarde van granate as ’n goeie bron van minerale elemente sowel as farmaseutiese, kosmetiese en antioksidant-verbindings te bevorder. Dit bied ook kennis oor die ontwikkeling van wetenskapgegronde instrumente vir die vasstelling van optimale vrugrypheid en naoes-hanteringsprotokolle om gedurende die naoes-hantering en -bemarking van granate vruggehalte te behou en verliese te verminder.

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 116-125).
Reducing material use is a major driver for cost reduction of crystalline silicon photovoltaic modules. The dominant wafer fabrication process employed in the industry today, ingot casting & sawing, wastes approximately half of the input silicon feedstock due to sawdust (kerf) and ingot tailings. Alternative "kerfless" wafer-fabrication technologies avoid ingot casting and sawing, and can reduce the amount of silicon feedstock used by over 5x. But for kerfless silicon to be cost effective, wafers must be of high electrical quality, as the power conversion efficiency of a photovoltaic module is the strongest determinant of manufacturing cost. Epitaxially grown kerfless silicon has the potential to both significantly reduce silicon waste, and provide sufficient electrical quality to support high-efficiency photovoltaic modules because of its single-crystal structure and low structural defect density. The goals of this research effort are to identify the root cause of underperformance of epitaxial wafers, to develop defect-mitigation strategies, and to translate these to electronic performance improvements. Low carrier lifetimes, a measure for electrical performance, of < 1 is were observed in as-grown epitaxial material. Injection level dependent lifetime, bulk mass spectrometry (ICP-MS), deep level transient spectrometry (DLTS), and micro x-ray fluorescence ([mu]-XRF) measurements were completed to identify underlying performance-limiting defects. The comparison of the defect concentrations obtained in the above measurements to Shockley-Read-Hall (SRH) recombination modeling indicates that a getterable impurity contaminant is the primary performance limiting defect in p-type as-grown material. The gettering response of p-type epitaxial material is assessed for two generations of wafer growth equipment. In the first generation of material, gettered lifetimes were < 20 [mu]s at an injection level of 10¹⁵ cm-³ . While a significant improvement over as-grown performance, this performance level is inadequate for high-efficiency photovoltaics. A second generation of material was grown in an upgraded environment with improved impurity management and greater automation. The effective lifetime of the second generation of material improved over lOx. With the application of standard and extended phosphorus diffusion gettering processes, effective lifetimes of over 300 [mu]s and estimated bulk lifetimes over 800 [mu]s are achieved in < 100 pm thick p-type epitaxial wafers at an injection level of 10¹⁵ cm-³ with highly effective Al₂O₃ surface passivation. Very low concentrations of interstitial iron, a dominant defect in p-type c-Si, were achieved after standard (2.5 +/- 0.76)x10¹⁰ cm-³ and extended (3.2 +/- 7.4)x10⁹ cm-³ gettering processes. With bulk mass spectrometry and SRH recombination modeling, the source for the lifetime change between generations is identified as a reduction in contamination of difficult to getter impurities including Mo and V. Other potential performance limiting defects, including interstitial iron contamination and structural defect density, are not observed to change between generations. Both the excellent gettering response and low as-grown lifetime of the material is attributed to the rapid cooling and low density of heterogeneous nucleation sites in as-grown material. This leads to a large concentration of point-defects, a more recombination active configuration than precipitates, in as-grown material. Controlled pre-gettering annealing experiments of as-grown material showed that material performance after gettering can be reduced with pre-gettering annealing. Similarly, as-grown and gettered material was assessed for n-type epitaxial wafers. As-grown lifetime is again low, < 1 [mu]s, but improves to over 800 [mu]s (effective) at an injection level of 10¹⁵ cm-³. In the as-grown state, a getterable impurity is indicated to limit lifetime. The effective lifetime of over 800 [mu]s at an injection level of 10¹⁵ cm-³ of the n-type material results in a calculated surface passivation effectiveness that matches the best results obtained with Al₂O₃ This indicates that no unintended contaminant is responsible for the performance of the wafer. In conclusion, very high effective lifetimes, eclipsing values achieved with historic kerfless silicon growth technologies, are demonstrated with epitaxial kerfless silicon for solar cells after gettering. The achieved lifetimes are capable of supporting high-efficiency device architecture. Using defect science, the underlying causes for underperformance of as-grown material and early generations of growth are indicated.
by Douglas M. Powell.
Ph. D.

Self-assembled III-V quantum dots (QDs) attract intense research interest and effort due to their unique physical properties arising from the three-dimensional confinement of carriers and discrete density of states. Semiconductor III-V QD laser structures exhibit dramatically improved device performance in comparison with their quantum well (QW) counterparts, notably their ultra low threshold current density, less sensitivity to defects and outstanding thermal stability. Therefore, integrating a high-quality QD laser structure onto silicon-based platform could potentially constitute a hybrid technology for the realization of optical inter-chip communications. This thesis is devoted to the development of high-performance InAs/GaAs QD lasers directly grown on silicon substrates and germanium substrates for silicon photonics. In the integration of III-V on silicon, direct GaAs heteroepitaxy on silicon is extremely challenging due to the substantial lattice and thermal expansion mismatch between GaAs and Si. The inherent high-density propagating dislocations can degrade the performance of III-V based lasers on silicon substrates. To enhance the device performance, QW dislocation filters are used here to create a strain field, which bends the propagating dislocations back towards the substrate. Here, we report the first operation of an electrically-pumped 1.3-\mu m InAs/GaAs QD laser epitaxially grown on Si (100) substrate. A threshold current density of 725 A/cm2 and an output power of 26 mW has been achieved for broad-area lasers with as-cleaved facets at room temperature. To avoid the formation of high-density threading dislocations (TDs), an alternative to direct growth of GaAs on silicon substrate is to use an intermediate material, which has a similar lattice constant to GaAs with fewer defects. Germanium appears to be the ideal candidate for a virtual substrate for GaAs growth, because germanium is almost lattice-matched to GaAs (only 0.08% mismatch). In the last 20 years, the fabrication of germanium-on-silicon (Ge/Si) virtual substrates has been intensely investigated with the demonstration of high-quality Ge/Si virtual substrates. The main challenge for the growth of GaAs on Ge/Si virtual substrate is to avoid the formation of anti-phase domains due to the polar/non-polar interface between GaAs and germanium. A new growth technique was invented for suppressing the formation of anti-phase domains for the growth of GaAs on germanium substrates at UCL. Based on this technique, lasing at a wavelength of 1305nm with a threshold current density of 55.2A/cm2 was observed for InAs/GaAs QD laser grown on germanium substrate under continuous-wave current drive at room temperature. The results suggest that long-wavelength InAs/GaAs QD lasers on silicon substrates can be realized by epitaxial growth on Ge/Si substrates. Studies in this thesis are an essential step towards the monolithic integration of long-wavelength InAs/GaAs QD lasers on a silicon substrate, as well as the integration of other III-V devices through fabricating III-V devices on silicon substrates.

Capsaicinoids are a class of compounds responsible for the "heat" of hot peppers. Capsaicin and dihydrocapsaicin have the highest burning effect. The aim of this work is to separate and quantify the two major capsaicinoids in fruits harvested at different stages of development and at different seasons. Simple and rapid HPLC method involves 73:27% methanol water mobile phase with C18 stationary phase and UV-Vis detector set at 210 nm. The method showed good reproducibility with 1.74% - 4.72% relative standard deviations, a linear response within 0.65–45.5 and 0.25-17.5 μg/mL for capsaicin and dihydrocapsaicin, respectively. The method achieved average recovery of 106% for capsaicin and 102% dihydrocapsaicin. Determination of capsaicinoids in four naturally grown chili and commercial source habanero were analyzed. The amount in the sample ranged from 1184-8156 μg/g for capsaicin and 430-3299 μg/g for dihydrocapsaicin.