Academic literature on the topic 'Net feed intake (NFI)'

Insulin-like growth factor-I (IGF-I) concentration measured in the blood plasma of 6520 seedstock Angus beef cattle (3622 bulls and 2898 heifers) from eastern Australia between 2002 and 2004 was used to estimate the heritability of IGF-I and phenotypic and genetic correlations with net feed intake (NFI) and other production traits. The average concentration of IGF-I was 314 ng/mL measured at the average age of 242 days. A moderate heritability of 0.35 was estimated for IGF-I. IGF-I was further defined as being measured either at, or prior to, weaning (average age of 201 days) or post-weaning (average age 310 days). The genetic correlation between IGF-I recorded at the different ages was 1.0 ± 0.04. IGF-I and NFI were found to have a genetic correlation of 0.41 ± 0.21. IGF-I had positive genetic correlations of 0.22 ± 0.14, 0.19 ± 0.14, and 0.26 ± 0.15 with ultrasound-scanned subcutaneous fat depth at the rump (P8) and 12/13th rib (RIB) sites and intramuscular fat % (IMF), respectively. Corresponding phenotypic correlations were 0.14, 0.13, and 0.12, respectively, for P8, RIB, and IMF. IGF-I had low to moderate negative genetic correlations with growth traits. Direct genetic correlations for IGF-I of –0.22 ± 0.08, –0.17 ± 0.09 and –0.10 ± 0.14 were estimated with birth (BWT), 200-day (WT200), and 400-day (WT400) weights, respectively. Genetic correlations between the direct component of IGF-I and maternal components of BWT and WT200 were 0.15 ± 0.13 and 0.31 ± 0.11, respectively. Phenotypic correlations of the direct component of IGF-I with the direct components of BWT, WT200, and WT400 were –0.10, 0.06, and 0.16, respectively. Ultrasound-scanned eye muscle area (EMA) and IGF-I had genetic and phenotypic correlations of –0.22 ± 0.15 and 0.13, respectively. This study showed that IGF-I is heritable and genetically correlated with important production traits. The genetic correlations indicate that selection for lower IGF-I concentrations would result in cattle that have lower NFI (i.e. more feed efficient), are leaner, with increased growth, and possibly decreased maternal weaning weight.

Recently, we have proposed a new theory of feed intake regulation in ruminants (Ketelaars and Tolkamp, 1992a,b; Tolkamp and Ketelaars, 1992). This theory attributes great significance to the efficiency of metabolizable energy (ME) utilization for feed intake regulation. In brief, we assume that feed intake behaviour of ruminants aims at maximizing the ratio of net energy intake (representing the benefits of feeding) relative to oxygen consumption (representing the metabolic costs of feeding). Starting from this assumption, we have shown that knowledge of the efficiency of ME utilization obtained under conditions of restricted feeding can be used successfully to predict voluntary intake (Tolkamp and Ketelaars, 1992).If, indeed, voluntary feed intake and the efficiency of ME utilization are so intimately related, the question comes up what the effect of ad lib feeding is on the overall efficiency of ME utilization (total net energy intake, NEI, as a fraction of ME intake, MEI). This paper investigates this question by means of model calculations for growing and lactating cattle according to the UK energy evaluation system.

The effect of feeding greater amounts of byproducts (BP) as a replacement for human-edible (HE) feed ingredients on nutrient intake, chewing activity, rumen fermentation, production performance, human-edible feed conversion efficiency (HeFCE) and net food production (NFP) of high-producing Holstein cows was evaluated. Twelve multiparous Holstein cows (BW = 673 ± 44, DIM = 112 ± 8 d; 48 ± 2.25 kg/d of milk; mean ± SE) were used in a replicated 3 × 3 Latin square design with 28-d periods. Each period consisted of 21 d of adaptation followed by 7 d of data collection. Treatments diets were (DM basis): (1) concentrate containing 26% byproducts (BP26; control); (2) concentrate containing 60% byproducts (BP60); and (3) concentrate containing 95% byproducts (BP95). Alfalfa hay (20% dietary DM) and corn silage (20% dietary DM) were included in all diets. Dietary concentrations of neutral detergent fiber (NDF), non-fiber carbohydrates (NFC), starch and ether extract (EE) were 32.1, 41.0, 26.14 and 3.4% (BP 26); 35.3, 36.0, 22.05 and 4.7% (BP60); and 38.2, 32.0, 17.96 and 6.1% (BP95), respectively (DM basis). Dry matter (22.07 kg/d) and NEL (35.16 Mcal/d) intakes did not differ among treatments. However, ether extract and NDF intakes increased, whereas starch intake decreased linearly as BP ingredients increasingly replaced HE feed ingredients. Eating time was not affected by dietary treatment, but ruminating and total chewing time tended to increase with increasing amounts of BP. Replacing HE with BP ingredients did not affect rumen pH. An increased proportion of BP ingredients in the diet linearly decreased propionate, isobutyrate, isovalerate and valerate concentrations in the rumen and increased acetate concentration and the acetate to propionate ratio. Replacing HE with BP ingredients did not affect milk yield. The yield of 3.5% FCM (39.12, 40.14 and 41.33 kg/d for BP26, BP60 and BP95, respectively) and fat content (2.95, 2.99 and 3.13 % for BP26, BP60 and BP95, respectively) linearly increased. Substituting BP ingredients for HE feed ingredients increased unsaturated fatty acids, monounsaturated fatty acids, polyunsaturated fatty acids, stearic acid, oleic acid and preformed fatty acids but decreased saturated fatty acids, palmitic acid, de novo and mixed fatty acids. Replacing HE with BP feed ingredients increased human-edible efficiency (HeFCE) for crude protein (1.06, 1.66 and 4.14 kg/kg edible for BP26, BP60 and BP95, respectively) and for energy (2.27, 3.62 and 9.22 MJ/MJ edible for BP26, BP60 and BP95, respectively) and also net food production (NFP) for crude protein (0.064, 0.52, and 1.00 kg/d for BP26, BP60, and BP95, respectively) and energy (62.8, 83.0 and 104.7 MJ/d for BP26, BP60 and BP95, respectively). Feeding byproduct-based concentrates instead of human-edible feed ingredients increase human-edible feed conversion efficiency (HeFCE), net food production (NFP) and improved the performance of high-producing Holstein cows.

Recent proposals have updated systems of feed units of energy, protein, structure and rumen fill. However, consistency between the largely independently built units has not been checked, even though energy, structure and fill values of feedstuffs are linked throughout feeding in ruminants. The target of this work was to build a mechanistic model to ensure consistency across equations related to intake, mastication, fill value of feeds and diets, digestion of organic matter and transit times. The first step was to build a large database of published results on digestion, intake and chewing in cattle. This database was studied by meta-analyses to calculate more than 100 empirical regressions; about half of these equations were used to build the new French systems of net energy and metabolisable protein. The other equations were mainly related to mastication (per day or kg dry matter intake, DMI), as well as the sizes and adjacent flows of 12 compartments inside the rumen: neutral detergent fibre (NDF), degradable (D) or not (U), in large or small particles; protein, soluble (S) or D and U; starch, S or D; water; volatile fatty acids; and microbes. The rumen digesta load (RL) was closely linked with the forage NDF intake, but in this dataset, there was no maximum RL, so it does not seem to limit DMI. Close relationships were observed between long-forage intake (NDFI, % of liveweight) and dietary forage NDF (%DM) and between mastication (min/day) and dietary index of mastication (min/kg DMI). Unlike RL, each of these two relationships exhibited obvious asymptotic maximum values for the duration of mastication per day (~1000 min/day) and for the level intake of NDF from long forages (1.35% of liveweight). In these two equations, the slope represented the level of DMI. The two equations were added to the other structural equations. It is therefore possible to use a mechanistic model with 12 compartments to consistently integrate aspects dealing with fill, chewing, DMI and energy value of rations in cattle.

The effects of raw and autoclaved Shoti (Curcuma zedoaria) meal on the growth and N utilization of growing broilers were determined. Shoti from Bangladesh Agricultural University campus was collected and sorted on the basis of white color of the rhizome. Then they were chopped into pieces, sun dried and pulverized in a flour mill. Aliquot samples were autoclaved at 1200C under 15 lb of pressure per square inch for 30 min. Autoclaved samples were stored in tightly lid contained for future use. 3 One hundred -day-old Cobb 500 broiler chicks were reared on the floor and a total of 24 growing broilers, 4 birds in each group were weighed on d 15 Two broilers were placed in each cage. There were a total of four experimental and two control (positive and negative Non-protein control) diets. Diets were fed ad libitum from day 15 to 33days. Body weight, feed intake, feed refusal and fecal weights were recorded every day. Cumulative feed efficiency per bird was calculated as the ratio of weight gained to feed consumed. Dry matter of excreta was determined from the last 10 d of feeding trial by drying aliquots of every day’s droppings by drying for 6 h at 1050C. On d 19, birds were bled to death. Immediately after slaughter, the carcasses were examined systematically. The chemical composition of Shoti meal showed that it is low in protein, fat and trace minerals and therefore mainly a source of energy. The bulk of the tuber (75 percent) consists of carbohydrates, made up of 10.6% fiber, and 64.9% nitrogen free extracts (NFE). A peculiarity of Curcuma rhizome meal contains high level of ash (9.9%) on DM basis. The results showed that at day 33, the weight of the broiler chicken fed shoti 100g, 200g, 300 g and 200g (autoclaved shoti meal)/ Kg diet was significantly different from the weight of the chicken fed on a maize-soybean diet. The birds given shoti meal consumed less feed than those provided with a maize diet. Feed efficiency or weight gain to feed ration over 19-d period was the poorest when fed 300 g Shoti/ Kg diet. Intake picked up when the shoti meal was incorporated after having been autoclaved and there was slight improvement in body weight gain as compared to that of other Shoti fed group. However, feed efficiency and body weight gain as % of initial weight remained significantly lower than the maize-soybean control. The inclusion of Shoti meal generally had an adverse effect on the apparent dry matter digestibility compared with the control diets. The group fed autoclaved shoti meal had a similar effect and the true N digestibility was the lowest when compared to those of control fed on maize-soybean meal. Thus, physical treatment like using autoclave, caused further reduction of digestibility of its N. Lipid digestibility was reduced by ingestion of shoti meal. Since the diets were isocaloric, after correction for the apparent endogenous lipid losses, which were obtained from the results of non-protein control feeding, the net faecal losses was around 66.2% of the ingested lipid against control diet fed birds. Bang. J. Anim. Sci. 2018. 47 (1): 40-46

The effects of replacing soybean meal with graded levels of fermented Senna obtusifolia seed meals (SOSM) on the growth performance of Clarias gariepinus were investigated. Five isonitrogenous (42% crude protein) and isocaloric (25.7% NFE) diets were formulated in which fermented replaced soybean meal (SBM) at 0% (SOSM0), 25% (SOSM25), 50% (SOSM50), 75% (SOSM75) and 100% (SOSM100) inclusion levels and a commercial feed (CmF) as the second control. Three hundred and sixty (360) fingerlings of (Clarias gariepinus) mean weight (2.85±0.01g) were stocked at (20) fish per tank volume in triplicate groups per treatment and fed 3% body weight twice a day of the experimental diets for 180 days. The feeding rate was adjusted after weighing. The water qualities were within range recommended for Clarias gariepinus. There were no significant differences (p> 0.05) in growth performance and nutrient utilization between the control groups and those fed the fermented SOSM diets at 25%. The commercial, 0% and 25% groups had the highest mean weight gain (279 to 280 g), significantly (P<0.05) superior to the groups that received the, 50%, 75% while the group that received 100% SOSM diet had the poorest mean weight gain (132.72g). Feed conversion ratios (FCR) of all treatments ranged from (1.75 to 2.18). These values increased slightly by increasing levels of fermented SOSM from 50 to 100%. The best FCR, 1.75± 0.02, recorded for fish fed 25% fermented SOSM indicated a superior level of utilization of the SOSM diet by the fish. There was no significant difference (P>0.05) in the protein intake among the group of fish fed 0 and 25%, but significant difference (P<0.05) occur in fish fed 50, 75 and 100% fermented SOSM respectively. Protein efficiency ratio (PER) exhibited significant differences (P<0.05) in all treatments except in the control diets that were not statistically different (P>0.05) from the fish fed the 25% fermented SOSM. The PER values increased among the experimental fish with respect to the quantity of total feed intake. There were no significant differences (P>0.05) in apparent net protein utilization (ANPU) among treatments CmF, 0% and 25%. The ANPU was highest in fish fed 0% fermented SOSM (91.6±0.04) while fish fed 75 and 100 % fermented SOSM in diets were 71.4±0.02 and 73.4±0.03 were the least. There was a significant (P<0.05) difference in the effect of the inclusion levels of fermented (SOSM) on final body carcass composition among treatments. This study showed that soybean meal can be substituted with fermented Senna obtusifolia seed meal up to 25% level in Clarias gariepinus diets without any negative effects on the growth and feed efficiency.

The high cost of feed has become a great challenge in poultry production. Good quality and cheap feed is therefore crucial for optimal growth performance of poultry chickens. In this study the effect of Euphorbia heterophylla Leaf Meal (EHLM) on the performance, carcass characteristics, nutrients digestibility and economics were evaluated. Broiler chicks numbering one hundred and eighty (180) of Ross 308 strain were fed for 4 weeks. The birds were randomly allotted to six experimental diets with three replications of 10 birds each. The diets were formulated with the inclusion of EHLMat 0, 5, 10, 15, 20 and 25% levels, for T1, T2, T3, T4, T5 and T6 which replaces soyabean meal respectively and data collected were subjected to analysis of variance in a completely randomized design. Results obtained indicated that the experimental diets significantly (P<0.05) affected the average feed intake and average daily protein intake, while the average daily weight gain, average feed conversion ratio, average daily protein efficiency ratio and average final live weight were not affected (P>0.05); mortality was not affected (P>0.05) by the diet. Carcass parameters, carcass cut and internal organs such as fasted liveweight, plucked weight, dressed weight, breast weight, thigh, drum stick, neck, shank and wings, heart, empty gizzard, lungs, spleen, pancreas, small intestine and esophagus weights showed no significant (P>0.05) difference while back, head, liver, proventriculus, kidney, abdominal fat, large intestine and caeca weight were significantly (P<0.05) different. The GIT length was affected (P<0.05) by the diet except the caeca length. The nutrient digestibility of CP and NFE did not showed significant (P>0.05) effect, but CF, EE and Ash were affected (P<0.05) by the dietary treatments. The nutrient digestibility of 5%, 10%, 15% and 25% were higher than the control diet(0%) for the five nutrients evaluated. The economics of production showed that feed cost (N/kg weight gain), total income (birds sold) and total profit (net gain) were not significantly (P>0.05) different while the feed cost (N/chicken), cost saving due to EHLM inclusion, total cost of production (N/chicken) and feed cost as percentage of total cost were significantly (P<0.05) affected by the test diets. The result showed that birds fed diet containing 15% have better economic advantage for optimum benefit. Therefore 15% EHLM replacement of soya bean is recommended for adoption for optimum growth performance, carcass yield, nutrient digestibility and economics of production in finisher broiler chicken. Le coût élevé des aliments pour animaux est devenu un grand défi dans la production avicole.Une alimentation de bonne qualité et bon marché est donc cruciale pour des performances de croissance optimales des poulets de volaille. Dans cette étude, l'effet de la farine de feuilles d'Euphorbia heterophylla (EHLM) sur la performance, les caractéristiques de la carcasse, la digestibilité des nutriments et l'économie ont été évalués. Des poussins de chair au nombre de cent quatre-vingts (180) de souche Ross 308 ont été nourris pendant 4 semaines. Les oiseaux ont été répartis au hasard dans six régimes expérimentaux avec trois répétitions de 10 oiseaux chacune. Les régimes ont été formulés avec l'inclusion d'EHLM à 0, 5, 10, 15, 20 et 25%, pour T1, T2, T3, T4, T5 et T6 qui remplace respectivement le tourteau de soja et les données collectées ont été soumises à une analyse de variance. dans une conception complètement aléatoire. Les résultats obtenus ont indiqué que les régimes expérimentaux affectaient significativement (P<0,05) la consommation alimentaire moyenne et la consommation quotidienne moyenne de protéines, tandis que le gain de poids quotidien moyen, le rapport de conversion alimentaire moyen, le rapport d'efficacité protéique moye quotidien et le poids vif final moyen n'étaient pas affectés ( P>0,05) ; la mortalité n'a pas été affectée (P>0,05) par le régime alimentaire. Les paramètres de la carcasse, la coupe de la carcasse et les organes internes tels que le poids vif à jeun, le poids plumé, le poids paré, le poids de la poitrine, le poids de la cuisse, de la baguette, du cou, du jarret et des ailes, le poids du cœur, du gésier vide, des poumons, de la rate, du pancréas, de l'intestin grêle et de l'œsophage ont été montrés aucune différence significative (P> 0,05) alors que le poids du dos, de la tête, du foie, du proventricule, des reins, de la graisse abdominale, du gros intestin et des caeca étaient significativement différents (P< 0,05). La longueur GIT a été affectée (P < 0,05) par le régime, à l'exception de la longueur des caeca. La digestibilité des nutriments du CP et du NFE n'a pas montré d'effet significatif (P>0,05), mais CF, EE et Ash ont été affectés (P<0,05) par les traitements diététiques. La digestibilité des nutriments de 5 %, 10 %, 15 % et 25 % était supérieure à celle du régime témoin (0 %) pour les cinq nutriments évalués. L'économie de la production a montré que le coût de l'alimentation (N/kg de gain de poids), le revenu total (oiseaux vendus) et le bénéfice total (gain net) n'étaient pas significativement différents (P>0,05) alors que le coût de l'alimentation (N/poulet), la réduction des coûts en raison de l'inclusion de l'EHLM, le coût total de production (N/poulet) et le coût des aliments en pourcentage du coût total ont été significativement (P<0,05) affectés par les régimes d'essai. Le résultat a montré que les oiseaux nourris avec un régime contenant 15 % ont un meilleur avantage économique pour un bénéfice optimal. Par conséquent, il est recommandé d'adopter un remplacement EHLM de 15 % du soja pour des performances de croissance optimales, un rendement en carcasse, une digestibilité des éléments nutritifs et des économies de production dans le poulet de chair de finition.

Females from lines of mice divergently selected for post-weaning net feed intake maintained significant line differences in daily feed intake (0.8 g/day difference, 22%) and net feed intake (± 0.35 g/day respectively) both before and during pregnancy. Dam/litter units converged completely for daily feed intake immediately in the postnatal stage, during a period of negative energy balance when feed intake and rate of gain were both maximised. Feed intake net of that required for growth and maintenance of liveweight was effectively zero for both lines during this 2-week period. The lines re-diverged in late-lactation. Variance for all traits increased substantially over the 11�weeks of the experiment.In an extensive production environment, where peak lactation generally coincides with abundant pasture supply, this short convergence would have little impact on overall production efficiency. Consequently, selection for post-weaning net feed intake based on growth/weight components remains a potential means to improve production efficiency.

Net feed efficiency refers to variation in feed consumption between animals net of requirements for maintenance and production, and may be measured as residual feed intake (RFI). Because RFI is independent of liveweight (LW) and growth rate, selection for improved net feed efficiency is likely to reduce feed intake with little change in growth. The purpose of this study was to establish whether there exists genetic variation in RFI in young British Hereford bulls, and to determine the phenotypic and genetic correlations of RFI with key production traits.The data consisted of performance measurements on 540 bull progeny of 154 British Hereford sires, collected over ten 200-day postweaning performance tests conducted between 1979 and 1988. The traits analysed were food intake (FI), 200 to 400-day daily gain (ADG), 400-day weight (W400), predicted carcass lean content (LEAN), lean growth rate (LGR), food conversion ratio (FI/ADG) and lean FCR (LFCR; FI/(ADG x LEAN), described by Bishop (1992).

Seven generations of divergent selection on a phenotypic index of net feed in mice produced a realised heritability estimate of 0.27 ± 0.07. Despite small negative genetic correlations of net feed intake with daily gain and liveweight, correlated responses in these economically important traits were negligible. Still, more efficient animals tended to be fatter during the early post-weaning phase. Gross digestibility was also affected, which may have implications for the overall energy balance of a biological system.

O consumo alimentar residual (CAR) é uma medida de eficiência alimentar independente do crescimento e do peso à maturidade. O melhoramento genético para CAR pode reduzir o custo de alimentação de bovinos, porém uma melhor compreensão dos processos biológicos relacionados ao CAR é necessária. Além disso, associações entre CAR e qualidade de carcaça têm sido pouco investigadas em raças zebuínas. Desta forma, o objetivo com este estudo foi avaliar o metabolismo protéico, a composição corporal, as características de carcaça e a qualidade de carne em bovinos zebuínos com alto e baixo CAR. Adicionalmente, foi testada a hipótese da existência de interações entre CAR e peso vivo ao abate para características de carcaça e composição corporal. Setenta e dois novilhos da raça Nelore (16 a 21 meses de idade, 334±19 kg de peso vivo inicial [PV]) foram mantidos em confinamento e alimentados ad libitum (74,5% NDT; 14,3%PB) por 70 dias. O consumo de matéria seca (CMS) e o ganho médio de peso (GMD) diários foram medidos individualmente. Os 12 novilhos com maior CAR e os 12 com menor CAR foram classificados como grupos de alto e baixo CAR, respectivamente (fase de seleção) e foram alimentados até quando alcançassem pesos vivo ao abate de 460, 490, 520 e 550 kg (fase de terminação). Antes do abate, foi realizada colheita total de urina para a determinação da excreção diária de 3-metil-histidina e da taxa fracional de degradação miofibrilar. A composição química corporal foi estimada pelo método de diluição isotópica utilizando óxido de deutério. A maciez objetiva da carne e a atividade de proteases cálcio-dependentes foram determinadas no músculo Longissimus. Na fase de seleção, novilhos com baixo CAR tiveram menores CMS, conversão alimentar, CAR e ganho de gordura sobre a garupa que novilhos com alto CAR, mas nenhuma diferença foi observada no GMD, no PV final, na gordura subcutânea e na área do Longissimus. Na fase de terminação, nenhuma interação foi observada entre CAR e PV ao abate. Não houve diferenças entre animais mais e menos eficientes quanto ao peso e rendimento de carcaça, gordura renal, pélvica e inguinal, vísceras, área de Longissimus, gordura subcutânea, marmorização, aparas e porção comestível. Novilhos com baixo CAR apresentaram menos gordura sobre o trato gastrintestinal (TGI) que novilhos com alto CAR. Não foram observadas diferenças quanto ao índice de fragmentação miofibrilar, força de cisalhamento e atividade do sistema calpaína. As taxas fracionais de degradação, síntese e acréscimo protéico foram similares entre os grupos de CAR. Novilhos Nelore com baixo CAR depositaram menos gordura subcutânea na carcaça em pesos vivos entre 340 e 460 kg. Em pesos mais elevados (460-550 kg), as características de carcaça e a composição corporal não foram influenciadas pelo CAR, mas indivíduos menos eficientes apresentaram maior massa de gordura visceral. A seleção de bovinos zebuínos para baixo CAR pode diminuir a ingestão de alimentos e melhorar sua eficiência alimentar, sem comprometer a qualidade da carne.
Residual feed intake (RFI) is a feed efficiency trait that is independent of growth rate and mature weight. Genetic improvement in RFI may reduce the costs of feeding cattle, however a better understanding of biological processes underlying variation in RFI is necessary. Moreover, associations between RFI and carcass quality have been poorly investigated in Zebu breeds. Therefore, this study aimed to evaluate protein metabolism, body composition, carcass traits and meat quality in high- and low-RFI Zebu cattle. In addition, the hypothesis that there are interactions between RFI and harvest body weight for carcass traits and body composition was investigated. Seventy-two Nellore steers (16 to 21 month-old, 334±19 kg initial body weight [BW]) were fed a finishing ration (74.5% TDN, 14.3%CP) on an ad libitum basis, for 70 days. Daily dry matter intake (DMI) and body weight gain (ADG) were measured individually. The 12 lowest and the 12 highest RFI steers were classed as low- and high-RFI groups, respectively (selection phase), and were fed until reaching slaughter BW of 460, 490, 520 and 550 kg (finishing phase). Before slaughter, total urine was collected for determination of daily 3-methylhistidine excretion and myofibrillar protein breakdown rates. Body chemical composition was estimated by the isotope dilution method using deuterium oxide. Objective tenderness and Ca+2-dependent protease activities were measured on Longissimus muscle. In the selection phase, low-RFI steers had lower DMI, feed:gain, RFI, and ultrasound rump fat thickness gain than high-RFI cattle, but no differences were observed for ADG, final BW, ultrasound fat thickness and Longissimus area. In the finishing phase, no interactions were observed between RFI and slaughter BW. No differences between more and less efficient cattle were observed for hot carcass weight, dressing percentage, kidney, pelvic and inguinal fat, visceral mass, Longissimus area, backfat thickness, marbling score, trimmings and retail product yield. Low-RFI steers presented less fat on the gastrointestinal tract (GIT) than high-RFI cattle. No differences were observed for myofibrillar fragmentation index, Warner-Bratzler shear force and calpain system activities. Fractional rates of protein degradation, synthesis and accretion were similar between high- and low-RFI cattle. Low-RFI Nellore steers may store less subcutaneous carcass fat at body weights ranging from 340 and 460 kg. At higher body weights (460-550 kg), carcass traits and body composition are not affected by RFI, but least efficient cattle present greater visceral fat mass. Breeding zebu cattle for improved RFI may decrease feed intake and improve feed efficiency without compromising meat quality.

O objetivo deste trabalho foi estimar as exigências e a eficiência energética de vacas de corte lactantes e não gestantes, bem como do par vaca/bezerro. Posteriormente foi correlacionada a eficiência do par vaca/bezerro durante a lactação com a eficiência das mesmas vacas durante a terminação. Na fase de lactação os pares vaca/bezerro foram avaliados desde após o nascimento (17±5, d DP) até a desmama (210 d). Após a desmama foi conduzido o ensaio de terminação (67 d) e abate somente das matrizes. Foram avaliadas 10 vacas adultas ½ Caracu x Nelore (CN) e 10 ½ Angus x Nelore (AN), acasaladas com touros Red Angus (RA) e Canchim (CC), respectivamente. Na lactação o oferecimento da dieta (2,30 Mcal EM/kg e 12,4% PB) variou individualmente ao longo do período com objetivo de manter constante o peso das matrizes ao longo da lactação. A mesma dieta foi oferecida a vontade para a progênie. Durante o ensaio de terminação em confinamento a dieta (2,37 Mcal EM/kg e 10,5% PB) foi fornecida à vontade. A ingestão de matéria seca das matrizes foi de 92,4 g MS/kg PM0,75 (CV=3,2%; P=0,458). Vacas AN apresentaram produção de leite corrigida para gordura 12% superior (P<0,05). A concentração energética do leite (Mcal/kg) das vacas CN foi 9,4% superior (P<0,05). A eficiência (Mcal leite/Mcal EM ingerida) não foi diferente. A exigência de energia metabolizável de lactação (EMl) foi maior (P<0,05) para vacas AN em relação as CN, 90,1 e 74,2 (EMl, kcal EMl/kg PM0,75), respectivamente. Bezerros ½CC¼AN¼NE apresentaram ingestão de energia metabolizável (IEM) proveniente do leite 11,3% (P<0,05) superior. Bezerros ½RA¼CR¼NE foram 10,7% mais eficientes (g GP210d/Mcal IEM leite+dieta sólida). Não houve diferença para eficiência dos pares vaca/bezerro, contudo houve considerável variação individual, onde a eficiência média foi 35,3 g GP210d/Mcal IEM par (CV=11,5%). A eficiência do par foi positivamente relacionada ao ganho do bezerro (r=0,79; P<0,01) e negativamente relacionada à IEM do par (r=-0,58; P<0,05). Vacas CN ao abate apresentaram EGS 29% menor, AOL 13% maior e maior proteína no corpo vazio (P<0,05). Vacas AN apresentaram 14,7% maior proporção de órgãos internos relativo ao peso vazio e maior peso dos intestinos (P<0,01). As correlações fenotípicas demonstraram associação entre as eficiência de secreção do leite das vacas nas fase de lactação e de ganho de peso na fase de terminação (r=0,43; P=0,09). A eficiência de secreção de leite das vacas na lactação apresentou correlação com a eficiência do par (r=0,68; P<0,01). O consumo alimentar residual (CAR) das vacas na terminação foi correlacionado com o CAR das vacas em lactação (r=0,53; P<0,05) e com o CAR dos pares (r=0.62; P<0.01). Isso indica que vacas de corte mais eficientes durante a terminação são também mais eficientes no período de cria.
This study estimated the requirements and feed efficiency of non-pregnant lactating beef cows, as well as cow calf pairs. It also correlated the efficiency of the cows and their progeny during lactation to efficiency determined for the same cows in a finishing trial after weaning. In the lactating phase cow calf pairs were evaluated from just after birth (17±5, d) to weaning at 210 d. The finishing trial for the mature cows started after weaning and lasted 67 d after wich cows were slaughtered. Twenty adult cows were evaluated, 10 ½ Caracu x Nelore (CN) and 10 Angus x Nelore, bred to Red Angus (RA) and Canchim (CC) bulls, respectively. During lactation the diet (2.30 Mcal ME/kg and 12.4% CP) was offered in variable amounts to maintain individual live weight and condition score constant. The same diet was offered ad libitum to the calves. During the finishing phase cows were fed ad libitum (2.37 Mcal ME/kg e 10.5% CP). The dry matter feed intake of cows was 92,4 and SD 2,9 g DM/kg BW0,75. AN cows had fat corrected milk 12% higher compared to CN cows (P<0.05). However, milk energy content (Mcal/kg) was 9.4% higher (P<0.05) for CN cows. Efficiency of milk production (Mcal milk/Mcal ME intake) was not different. Metabolizable energy for lactation (MEl) was higher (P<0.05) for AN cows in comparison to CN, respectively 90.1 and 74.2 (MEl, kcal MEl/kg BW0,75). ME milk intake was 11.3% (P<0.05) higher for ½CC¼AN¼NE calves. Rates of gain were not different between calves, but ½RA¼CR¼NE were 10.7% more efficient (g LWG210d/Mcal MEI milk+solid diet). There was no difference in cow calf pairs efficiency, but there was a great individual variability with a mean of 35,31 g and SD of 4,08 g LWG210d/Mcal EM for the pair. Cow/calf pair efficiency was positively related to calf weight gain (r=0.79; P<0.01) and negatively to the pair metabolizable energy intake (r=-0.58; P<0.05). At slaughter CN cows presented backfat thickness 29% lower, longissimus muscle area 13% higher and higher empty body weight protein (P<0,05). AN cows had 14.7% higher relative internal organ weight and higher total intestine weight (P<0.01). The phenotypical correlations between efficiency indexes indicate moderate association between cow efficiency measured during lactation and in a short finishing period after weaning (r=0.43; P=0.09). Exist correlations between cow efficiency lactation and efficiency of the pair (r=0.68; P<0.01). Residual Feed Intake (RFI) during the finishing phase was moderately correlated to the RFI calculated during the lactation period for the cow calf pairs RFI (r=0.62; P<0.01) and the cows (r=0.53; P<0.05) indicated that beef cows more efficient in feed conversion during the finishing phase are more efficient during the lactation period.

The work presented in this thesis was undertaken to identify regions of the mouse and cattle genomes' containing quantitative trait loci (QTL) and candidate genes for net feed intake (NFl). Prior to mapping QTL in mice, a number of experiments were performed on mice from the eleventh generation of selection for divergent NFl to quantify the effects of selection for NFl on growth, body composition, protein turnover, metabolic rate, activity, and gastric emptying. Eleven generations of selection for and against NFl did not significantly alter body weight or growth rate. Mice from the high NFl selection line contained 32% less body fat, were 85% more active with no significant difference in body weight, growth rate or protein synthesis. There was a significant diflerence in gastric emptying of solid food between the mice lines with the high NFI mice grinding (25%) and emptying (21%) their gastric contents faster than the low NFl mice. This difference indicates the potential for gut hormones that regulate gastric emptying such as cholecystokinin, gastrin, motilin, secretin, and peptide YY as candidate genes for NFL. Cattle that were more efficient (lower NFl) had lower maintenance requirements, and consumed less feed per day. The eye muscle area, peak force of the LD muscle and meat, fat and bone weight significantly influenced NFI. However, only 17% of the variation in NFl was accounted for by these traits. Also, eating rate, number of feeding sessions per day and time spent feeding influenced NFl, accounting for 15% of the variation in NFI. Low NFI cattle ate slower, spent less time feeding and had fewer trips to the feeder than those animals with higher NFl suggesting a possible action of the serotonin and/or dopamine systems as candidate genes for NFI. Multiple interval mapping revealed nine NFl QTL in F₂mice from the eighth generation of selection for divergent NFI. Interval mapping, a simpler method for QTL mapping was used in Limousin-jersey backcross cattle and detected four QTL for NFl on BTA 1, 8, 9, and 20. The comparative gene maps between cattle and mice revealed that NFl QTL located on BTA 1 and 20 were comparative with the NFl QTL detected on MMU 16 and 13 respectively. A further two QTL that were almost significant in cattle on BTA 6 and 16 were also comparative with two of the mouse NFl QTL (MMU 1 and MMU 5 respectively). Based on these cattle QTL results and certain assumptions regarding NFl, selection for NFl in stud bulls would appear to be profitable for a producer. Validation of these QTL in other beef cattle breeds is required before commercialisation of any DNA based test. There were 19 genes in these four regions that could act as candidates for NFl located in these regions. Overall, the neurotransmitters appear to be the most promising candidate genes making up 11 of the potential 19 candidate genes identified. However, further biochemical and gene expression studies are required in cattle to confirm or contradict this.
Thesis (Ph.D.) -- University of Adelaide, School of Agriculture and Wine, 2004

The objectives of this study were to evaluate the effects of residual feed intake (RFI) classification on performance, feed efficiency, feeding behavior and carcass traits, and to determine the relative importance of individual performance and carcass measurements on between-animal variation in net revenue of feedlot steers. Performance, feed intake and feeding behavior traits were measured in 508 Angus-based composite steers, using the GrowSafe feed-intake measurement system, while fed a high-grain diet for 70 days. Residual feed intake (RFI) was computed as actual minus expected dry matter intake (DMI) derived from regression of DMI on average daily gain (ADG) and mid-test BW0.75, and steers classified into low (n = 150), medium (n = 200) and high (n = 158) RFI groups. Following the feed-intake measurement periods, steers were fed the same diet in group pens and harvested at an average backfat thickness of 1.14 cm. Net revenue (NR) was calculated as carcass value minus feeder calf, yardage, and feed costs using 3-year average prices. Feed cost was based on actual feed consumed during the feed-intake measurement periods, and model-predicted intake adjusted for RFI during the group-feeding periods. Steers with low RFI had $48/hd lower (P < 0.0001) feed cost, $16/hd numerically higher (P = 0.29) carcass value, and $62/hd more favorable (P < 0.0001) net revenue compared to their high-RFI counterparts. Net revenue was correlated with carcass weight, marbling score, yield grade, DMI, ADG, RFI and G:F ratio where animals that consumed more feed, had higher rates of gain and were more efficient had more favorable net returns. Models predicting net revenue from performance, carcass quality, and feed efficiency traits accounted for 77% of the between-animal variation in NR. In the base model, that included all traits performance, carcass quality and feed efficiency traits explained 28, 14 and 35%, respectively, of the variation in NR. Results from this study indicate that between-animal variation in net revenue was impacted to a great extent by performance and feed efficiency, rather than carcass quality traits, in Angus-based composite steers based on average 3-year pricing scenarios.

Includes list of publications produced during the period of candidature
Includes bibliographical references (leaves 254-274)
xiv, 274 leaves : ill. (col.) ; 30 cm.
Title page, contents and abstract only. The complete thesis in print form is available from the University Library.
Thesis (Ph.D.)--University of Adelaide, Dept. of Animal Science, 2003

The INRA Feeding System for Ruminants has been renewed to better address emerging challenges for animal nutrition: prevision of productive responses, product quality, animal health and emissions to the environment, in a larger extent of breeding contexts. The new system is mainly built from meta-analyses of large data bases, and modelling. The dietary supply model accounts for digestive interactions and flows of individual nutrients, so that feed values depend on the final ration. Animal requirements account for variability in metabolic efficiency. Various productive and non-productive animal responses to diets are quantified. This book presents the whole system for dairy and meat, large and small ruminant production, including specificities for tropical and Mediterranean areas. The first two sections present biological concepts and equations (with their field of application and statistical accuracy) used to predict intake (including at grazing) and nutrient supply (Section 1), animal’s requirements and multiple responses to diets (Section 2). They apply to net energy, metabolisable protein and amino acids, water, minerals and vitamins. Section 3 presents the use of concepts and equations in rationing with two purposes: (1) diet calculation for a given performance objective; and (2) prediction of the multiple responses of animal to diet changes. Section 4 displays the tables of feed values, and their prevision. All the equations and concepts are embedded in the fifth version of INRAtion® software for practical use.

<em>Abstract</em>.—Thiamine concentrations in representative Great Lakes prey fish, including alewives <em>Alosa pseudoharengus</em>, rainbow smelt <em>Osmerus mordax</em>, slimy sculpin <em>Cottus cognatus</em>, bloater chub <em>Coregonus hoyi</em>, and lake herring <em>Coregonus artedi</em>, and their major dietary items, including mysids <em>Mysis relicta</em>, amphipods <em>Diporeia hoyi</em>, and net macroplankton, were measured to assess their potential involvement in depressed thiamine concentrations in lake trout <em>Salvelinus namaycush </em>of the Great Lakes. Mean thiamine concentrations in all biota were greater than the recommended dietary intake of 3.3 nmol/g for prevention of effects on growth, although the adequacy of these concentrations for reproduction is not known. Mean thiamine concentrations decreased in the order alewives > bloater chub, herring > smelt and differed from the order of associated egg thiamine concentrations published for lake trout feeding on these species (herring > alewives, smelt). As a result, these data strongly implicate the high thiaminase content, rather than the low thiamine content, of alewives and smelt as being responsible for the low egg thiamine concentrations of Great Lakes lake trout stocks that feed heavily on these species. Variations in thiamine content among prey species did not appear to be related to levels in their diet, because thiamine concentrations in <em>Mysis</em>, <em>Diporeia</em>, and macroplankton showed little consistency between group or between lake variation. There was no lake to lake variation in mean thiamine concentrations of prey species, but considerable within species variation occurred that was unrelated to size.

Abstract Aseptic loosening is a well-recognized phenomenon in cementless total knee replacement (TKR) and often carries severe consequences for the patient. We recently developed and tested in vitro a novel strategy for enhancing osseointegration and acute mechanical stability of orthopedic implants that employ laser-induced microgroove (LIM) and nanofiber membrane (NFM) applications at the bone-implant interface. We report herein investigation of the approach with results from a pilot study employing three skeletally mature female Spanish cross goats (∼4y, 35–45kg) receiving cementless TKR with a commercially available implant system (Biomedrix® Canine Total Knee). Pre-operative radiographs were taken to ensure limb normality and to select the appropriately sized implants for each goat. With the animal under general anesthesia and the limb properly prepped for aseptic surgery, the stifle was approached, and osteotomies of the proximal tibia and distal femur performed in preparation for implantation of the tibial (TT) and femoral (FT) trays. For one goat, the arthroplasty implant surfaces were unaltered from the manufacturer’s mirror-polished (MP) condition. For the other two goats, the TT bone-contact surface was laser-micro grooved (150 μm depth, 200 μm width, 200 μm spacing) prior to sterilization and then implanted with (LIM/NFM) or without (LIM) an intermediate (surface-applied) polycaprolactone (PCL) nanofiber mesh (50 × 50mm, electrospun, aligned, unidirectional, 10 μm thickness). Following surgery, animals received appropriate analgesic therapy and rehabilitative care to maximize animal comfort, function, and quality of life while limiting the risk of major complications. Post-operative monitoring included assessment of mentation, vital signs, pain level, digestive function (weight, appetite, rumen contractions, feed intake, fecal output), and limb status (usage, range of motion, muscular volume). By the study’s end (12 wks), all animals had recovered a pre-surgery range of motion in the operated knee and exhibited typical bony changes on radiographic follow-up. At necropsy following humane euthanasia, no gross instability of TKR components was observed. Histomorphometric analysis of explanted bone-TT constructs showed the increased new bone surface area in the LIM-NFM sample (0.49 mm2) compared with the MP sample (0.03 mm2), suggesting that microgrooves and/or PCL nanofiber coating may improve the clinical performance of the implant. A finite element analysis (FEA) model was developed to explore the impact of surface micro grooving to the mechanical stimuli at the bone-implant interface to supplement the in vivo studies. The three-dimensional geometry of the tibia was scanned using computed tomography and imported into a proprietary (MIMICS®) software to construct the solid models for finite element micro-strain analyses.

The evaporative gas turbine (EvGT), also known as the humid air turbine (HAT) cycle, is a novel advanced gas turbine cycle that has attracted considerable interest for the last decade. This high efficiency cycle shows the potential to be competitive with Diesel engines or combined cycles in small and intermediate scale plants for power production — and/or cogeneration. A 0.6 MW natural gas fired EvGT pilot plant has been constructed by a Swedish national research group in cooperation between universities and industry. The plant is located at the Lund Institute of Technology, Lund, Sweden. The pilot plant uses a humidification tower with metallic packing in which heated water from the flue gas economizer is brought into direct counter current contact with the pressurized air from the compressor. This gives an efficient heat recovery and thereby a thermodynamically sound cycle. As the hot sections in high temperature gas turbines are sensitive to particles and alkali compounds, water quality issues need to be carefully considered. As such, apart from evaluating the thermodynamic and part load performance characteristics of the plant, and verifying the operation of the high pressure humidifier, much attention is focused on the water chemistry issues associated with the recovery and reuse of condensate water from the flue gas. A water treatment system has been designed and integrated into the pilot plant. This paper presents the first water quality results from the plant. The experimental results show that the condensate contains low levels of alkali and calcium, around 2 mg/l Σ(K,Na,Ca), probably originating from the unfiltered compressor intake. About 14 mg/l NO2− + NO3− comes from condensate absorption of flue gas NOx. Some Cu is noted, 16 mg/l, which originates from copper corrosion of the condenser tubes. After CO2-stripping, condensate filtration and a mixed bed ion exchanger, the condensate is of suitable quality for reuse as humidification water. The need for large quantities of demineralized water has by many authors been identified as a drawback for the evaporative cycle. However, by cooling the humid flue gas, the recovery of condensed water cuts the need of water feed. A self supporting water circuit can be achieved, with no need for any net addition of water to the system. In the pilot plant, this was achieved by cooling the flue gas to around 35°C.