Dissertationen zum Thema „Geometridae Feeding and feeds“

Assignment (MPhil)--University of Stellenbosch, 2004.
ENGLISH ABSTRACT: The aim of this study was to evaluate the performance and profitability of different dietary specifications for broiler chickens slaughtered at 35 days of age. Two trials were performed to evaluate different production parameters. The results of these trials were compared to the predicted results of the EFG broiler model. No carcass data were available for the two trials mentioned above. Therefore, in order to evaluate the accuracy of the broiler model when predicting carcass characteristics, two published data sets (Leeson et al., 1996a) were used. Predicted and actual values were compared, evaluated and discussed. Two broiler trials were performed. In Trial One the amino acid density decreased throughout the range of three treatments from prestarter to finisher diets. In Trial Two the amino acid density decreased only in the four finisher diets. The main difference between predicted and actual results was the response to body weight. The model predicted a steady increase in feed intake to compensate for the lower dietary specifications while body weight did not change significantly. This increase in feed intake seems to be enough to maintain body weight. Trial birds also increased their feed intake as dietary amino acid density decreased, but this compensation seemed to be too low to maintain body weight compared to the control diet. The birds may find it easier to compensate when they have time to adapt to the specification. There is evidence in the literature that birds need seven days to adapt their feed intake to a lower feed specification (Leeson et al., 1996a). It can be speculated that the trial birds started to loose body weight due to a lower amino acid intake in this period. The model seems to adapt feed intake immediately after a change in diet specification. The simulation on literature data lead to the following conclusions: 1) Broilers posses the capacity to increase their feed intake with at least 65% should finisher diets with lower amino acid and energy concentrations be supplied. If only the energy concentration of finisher diets were decreased, the increase in feed intake will be around 30%. (see Table 16 and 23) 2) The accurate prediction of feed intake from the given dietary specification has a major influence on the accuracy of the prediction of broiler performance. 3) Amino acid density and DLys:ME ratio plays a significant role in the control and prediction of feed intake. The EFG broiler model is based on sound scientific principles. The model is comprehensive and can be used for a wide range of environmental and management conditions as well as dietary conditions. The nutritionist can use the model with confidence to assist in practical feed formulation. The actual strength of the model lies in the time and money being saved compared to practical trials.
AFRIKAANSE OPSOMMING: Die doel van hierdie studie is om die prestasie en winsgewendheid van braaikuikens te bepaal wanneer voere met verskillende digthede tot op 35 dae gevoer word. Twee eksperimente is uitgevoer om produksieresultate te evalueer. Die resultate van hierdie eksperimente is met die voorspelde waardes uit die EFG simulasie-model vergelyk. Aangesien geen karkasdata vir bogenoemde eksperimente beskikbaar was nie, is twee gepubliseerde datastelle gebruik om hierdie deel van die model te evalueer (Leeson et al., 1996a). Twee braaikuiken eksperimente is uitgevoer. Eksperiment Een het uit drie behandelings bestaan waarvan die aminosuur-konsentrasie vanaf dag een tussen behandelings verskil het. In Eksperiment Twee het die aminosuur-konsentrasie net in die vier afrondingsdiëte verskil. Liggaamsmassa op 35 dae het die grooste verskil tussen voorspelde- en werklike waardes getoon. Beide voorspelde en werklike innames het in albei eksperimente verhoog soos wat aminosuur-konsentrasie afgeneem het. Voorspelde liggaamsmassa het egter konstant gebly terwyl werklike data 'n afname in liggaamsmassa getoon het. Dit bleik dat die voorspelde toename in innames voldoende was om massa te onderhou terwyl die voëls in werklikheid nie genoeg gekompenseer het nie. Leeson et al., 1996a het tot die gevolgtrekking gekom dat braaikuikens minstens sewe dae benodig om hul voeriname by 'n nuwe spesifikasie aan te pas. So 'n stadige aanpassing kan daartoe lei dat energie- en aminosuur-inname daal indien 'n dieet met laer spesifikasie gevoer. Dit sal daartoe lei dat die kuikens liggaamsmassa verloor. Uit die literatuur simulasies is die volgende afleidings gemaak: 1) Braaikuikens besit die vermoeë om voerinname in die afrondingstyd met minstens 65% te verhoog indien 'n afrondingvoer met laer amiosuur- asook energiekonsentrasie gevoer word. Indien net die energiekonsentrasie verlaag word, sal die inname met sowat 30% verhoog. 2) Die akkurate voorspelling van inname is krities vir die akkurate voorspelling van produksieparameters. 3) Aminosuur-digtheid en DLys:ME speel 'n belangrike rol in die beheer en voorspelling van voerinname by braaikuikens. Die EFG braaikuikenmodel is op suiwer wetenskaplike beginsels geskoei. Die model is omvattend en kan vir 'n wye reeks van omgewings- en bestuurstoestande asook dieet-spesifikasies gebruik word. Die voedingkundige kan die model met vertroue gebruik om met praktiese voerformulering by te staan. Die model kan die formuleerder baie tyd spaar aangesien praktiese eksperimente ingeperk kan word.

This research reports on the determination of the effects of fish size and feed pellet size on the settling characteristics of Rainbow trout (Salmo gairdneri) culture, tank cleaning wastes. Flocculant particle settling curves (Type II) were developed from settling column analysis of cleaning wastes from 11-311 gram Rainbow trout fed a moist pellet diet (Oregon Moist Pellet ®). Four feed pellet sizes were investigated: 3/32, 1/8, 5/32 and 3/16 inch. Overall non-filterable residue removal curves and individual particle settling velocity distribution curves, derived from the Type II settling curve of each fish size and feed pellet size group, were compared. Slopes and y-intercepts of the linearized overall non-filterable residue removal curves and individual particle settling velocity distribution curves were compared using the Equality of Slope Test (S:SLTEST). Results of the test for a common regression equation indicated there were no significant differences in the proportional distribution of particle sizes within the cleaning wastes. Variations observed in the initial rates of removal within the overall non-filterable residue removal curves were considered insignificant Settling trials were pooled in order to obtain single curves, characterizing the overall solids removal rate and the individual particle settling velocity distribution of the waste solids.
Applied Science, Faculty of
Chemical and Biological Engineering, Department of
Graduate

A study was conducted using commercial broiler breeders with the males fed a diet containing, either 120/0 or 140/0 protein and body weight maintained at either 900/0 or 1000/0 of that recommended by the primary breeder (fed separately), or allowed to eat from the female feeders (controls). Female feeders in the separately fed pens were equipped with especially designed grills, which denied access to the males. The male feeder in these pens was elevated so that females were denied access.

Males fed separately (body weight 90% or 1000/0, and dietary protein 120/0 or 140/0) had a significantly higher percentage fertility (4.20/0) than males allowed to eat with the females. No differences in percentage fertility were found among the four separately fed groups. No differences were noted in percentage hatch of fertile eggs among any of the treatment groups.

Males eating from the female feeders had significantly heavier body weights and testes weights at 65 weeks of age than breeder males in the separately fed, groups. Mean body weights were 3819g and 4773g at 35 weeks of age, and 4192g and 5443g at 65 weeks of age for males eating separately and eating with the females, respectively. Furthermore, males in the control group had significantly larger breast angle measurements when compared with the separately fed males. No differences were observed in foot scores and semen concentration among males in the various treatment groups.

Master of Science

The aim of the first study was to determine if barley could replace maize as an energy source in concentrates fed to dairy cows grazing on kikuyu/ryegrass pasture without affecting the milk production, milk composition, or cause metabolic disorders. Sixty Jersey cows, in early to mid lactation were randomly allocated to one of five treatments (n = 12) based on feeding concentrates with different ratios of maize to barley, ranging from 100:0, 75:25, 50:50, 25:75 and 0:100, respectively. Concentrates contained 12 MJ ME kg -1 and 130g CP kg-1 DM and cows were fed 3 kg (as-is) concentrate after each milking for a period of 42 days (14-day adaptation and 28-day measurement). Cows strip-grazed the irrigated kikuyu/ryegrass pastures (15.7 ± 1.8 percent DM; 20.2 ± 4.3 percent CP; 44.7 ± 3.5 percent NDF). Milk weights were recorded daily and milk samples collected weekly and analyzed for milk fat and protein content. Body condition score and live weight were recorded at the start and end of the experimental period. Data of all the studies were subjected to a one-way ANOVA. Daily milk yield, FCM, MUN, milk fat yield, milk fat percent, protein yield, protein percent, live weight change, or body condition score change were not affected by treatment and values were 15.8 kg, 17.2 kg, 14.9 mg dl-1, 0.72 kg, 4.56 percent, 0.59 kg, 3.77 percent, 6.67 kg, and 0.15 BCS; 15.6 kg, 17.4 kg, 15.2 mg dl-1, 0.73 kg, 4.3 percent, 0.57 kg, 3.71 percent, 1.33 kg and 0.04 BCS; 17.2 kg, 17.9 kg, 15.2 mg dl-1, 0.74 kg, 4.36 percent, 0.63 kg, 3.71 percent, 0.33 kg and 0.08 BCS; 15.6 kg, 16.4 kg, 15.5 mg dl-1, 0.67 kg, 4.33 percent, 0.60 kg, 3.83 percent, -1.46 kg and 0.11 BCS; and 15.0 kg, 16.0 kg, 15.5 mg dl-1, 0.67 kg, 4.57 percent, 0.57 kg, 3.85 percent, 8.86 kg, and 0.05 BCS, respectively for the cows fed 100:0, 75:25, 50:50, 25:75 and 0:100 maize to barley ratio concentrate. According to these results, barley can replace maize without significantly affecting the milk production or milk composition. None of the cows presented any visible symptoms of acidosis. As it was clear from the results in the first study that maize could replace barley the aim of study 2A was therefore focused on determining the effect of feeding different levels of such a barley-based (2.4, 4.8 or 7.2 kg cow-1day-1) concentrate, on milk production, milk composition and live weight change of Jersey cows on kikuyu/ryegrass pasture (23.1 ± 2.95 percent DM, 11.1 ± 0.11 percent CP, 60.8 ± 0.58 percent NDF). Forty-five Jersey cows (early- to mid lactation), were randomly allocated to one of three treatments (n = 15) involving different levels of concentrate (12 MJ ME and 130g CP kg-1 DM) feeding for a period of 42 days (14-day adaptation and 28-day measurement). Milk weights were also recorded daily, and milk samples collected weekly, and analyzed for milk fat and protein. Body condition score and live weight were recorded at the start and end of the experimental period. The results of this study indicated that increasing the concentrate level from 2.4 to 4.8 and 7.2kg cow-1day-1 did not increase the milk yield (14.0 kg, 15.2 kg, 14.4 kg; P = 0.19). The FCM production increased from 15.8 to 17.5kg (P = 0.04) as the concentrate level increased from 2.4 to 4.8kg cow-1day-1. Increasing the concentrate from 4.8 to 7.2kg cow-1day-1 did not result in a significant increase in FCM. The milk protein percent increased significantly from 3.4 - 3.6 percent when the concentrate feeding level was increased from 2.4 to 7.2kg cow-1day-1. The MUN levels were 17.09 mg dl-1, 16.03 5 mg dl-1, and 16.36 mg dl-1 for the 2.4, 4.8 and 7.2kg cow-1day-1 concentrate levels, respectively. This is well within the recommended MUN levels (12 – 18 mg dl-1) indicating that sufficient protein was fed to cows. Increasing the concentrate level from 4.8 to 7.2 kg cow-1day-1 did not increase production, probably due to a higher pasture substitution rate. Supplementing large quantities of rapidly fermentable grains, such as barley, can suppress rumen pH and may have a negative effect on the rate and extent of fibre digestion in the rumen. Therefore the aim of study 2B was not only to determine the effect of feeding different levels of a barley-based concentrate, on milk production, milk composition and live weight change, but was also to determine the effect of a low (4.8 kg cow-1day-1) versus a high (7.2 kg cow-1day-1) level of barley-based concentrate supplementation on ruminal DM and NDF degradability of Westerworld ryegrass sampled from the pastures that these cows were grazing on. Sixty Jersey cows (early- to mid lactation), were randomly allocated to one of three treatments (n = 20) involving different levels of concentrate feeding. Concentrate (12 MJ ME, 130g CP kg-1 DM) was fed at 2.4, 4.8 or 7.2 kg cow-1day-1 for a period of 74 days (14-day adaptation and 60-day measurement). These cows stripgrazed irrigated kikuyu/ryegrass pastures (14.7 ± 4.37 percent DM, 25.1 ± 1.53 percent CP, and 44.4 ± 2.58 percent NDF) at a daily pasture allocation of 10 kg DM cow-1. Milk weights were recorded daily and milk samples collected weekly and analyzed for milk fat and protein. Body condition score and live weight were recorded at the start and end of the experimental period. Twelve Jersey cows, fitted with ruminal cannulae, were randomly allocated to two of the three treatments in the production study and received either 2.4 or 7.2 kg cow-1 day-1, of the same barley-based concentrate, in a two-period crossover design. These cows strip-grazed the same irrigated kikuyu/ryegrass pastures as the sixty cows in the production study. Each period consisted of 21 days for adaptation and seven days for data collection. Rumen liquor samples were collected every 4 hours within a 24-hour cycle and repeated once. Rumen pH was measured immediately, recorded, and the supernatant fluid preserved and frozen, pending VFA analysis. The in situ nylon bag technique was used to determine DM and NDF degradation and dried samples of Westerworld ryegrass pasture were incubated for 0, 4, 8, 12, 20, 30, 48, 72 and 96 hours. The data were fitted in the non-linear model p = a + b (1-exp-ct) (Ørskov & McDonald, 1979). Daily milk production, fat corrected milk, milk fat yield and milk fat percent were not affected by treatment and values were 17.3 kg, 18.4 kg, 0.76 kg and 4.42 percent; 19.0 kg, 20.0 kg, 0.82 kg and 4.35 percent; and 18.1 kg, 19.1 kg, 0.79 kg and 4.37 percent for the 2.4, 4.8 and 7.2 kg cow-1 day-1 concentrate treatments, respectively. Milk protein percentage of cows on the 7.2 kg concentrate cow-1 day-1 was significantly higher than that of cows on 4.2 kg concentrate cow-1 day-1 feeding level. Live weight increased significantly as the level of concentrate feeding increased and values were 17.9 kg; and 28.9 kg on the 2.4 and 7.2kg concentrate treatment, respectively. There was a significant increase in the live weight of cows that were fed 7.2 kg cow-1 day-1 (as-is) in comparison to those cows that were fed 2.4 kg concentrate cow-1 day-1 (as-is). This may have resulted from more nutrients being partitioned to live weight gain rather than milk production. No further response in milk production was observed when concentrate daily feeding was increased from 4.8 to 7.2 kg cow-1 day-1. It is postulated that the higher concentrate allowance resulted in a higher substitution rate and lower DMI intake from pasture. 6 There was no significant decline in the rumen pH (6.2 ± 0.4 and 6.2 ± 0.5) when the concentrate level was increased from 2.4 to 7.2 kg cow-1 day-1 (as-is). The total VFA (118.1 ± 45.9 and 139.4 ± 45.6 mmol L-1) and isovalerate (0.009 ± 0.07 and 0.248 ± 0.52 mmol L-1) increased significantly when the concentrate was increased from 2.4 to 7.2 kg cow-1day-1. No other rumen parameters were affected by treatment. Ruminal DM and NDF degradability of the Kikuyu/ryegrass pature were not affected by the level of concentrate supplementation. An increase in the concentrate level from 2.4 to 7.2 kg cow-1day-1 did not reduce degradability of either DM (94.67 ± 5.97, 94.49 ± 5.09; P = 0.919) or NDF (92.15 ± 8.69, 94.4 ± 11.73; P = 0.451), respectively. Results of rumen parameters and PD values were within the range reported by Bargo et al., (2003), viz. pH 5.76 – 6.29, NH3-N concentration 8.7 – 32.2 mg dl-1, total VFA concentration 90.3 - 151.4 mmol L-1 and PD values 89.5 – 93.5 % reported by Bargo et al. (2003). According to these authors, there is no simple relationship between any amount of the concentrate supplemented, and the ruminal pH and concentrate feeding only affects the in situ ruminal digestion of pasture when it is fed, at quantities higher than 8 kg DM cow-1day-1 (Bargo et al., 2003).

Thesis (MScAgric)--University of Stellenbosch, 2002.
ENGLISH ABSTRACT: Starch is the main component of cereal grains and is usually the primary energy source for pigs and poultry. Feed manufacturing can adopt several measures, including physical treatments such as milling or pelleting and other techniques, such as enzyme treatment, to disrupt cell structure. Grinding and pelleting are the most common food processing methods used for pigs. However, pelleting of complete balanced feeds is no longer such an economical proposition due to rising energy and equipment costs; therefore this cost has to be outweighed by an increased production efficiency. It has been known for many years that grinding is an essential prerequisite for the satisfactory blending of the ingredients of a multi-component food. Feed cost represents the major item in the cost of animal production. Without doubt, research and production efforts will continue to refine feed processing techniques to reduce the cost of feed and to increase the value of feed for a target animal. The possibilities for improvements in feed are endless; however the cost of each innovation must be carefully weighed against demonstrated improvements in animal performance. Experiment 1: The effect of feed processing techniques on weanling pig growth-performance The effects of processing of the carbohydrate source and the feed on growth performance of commercial Landrace x Large White piglets (n=480) weaned at 28 ± 2 d were investigated. Two processing combinations of the carbohydrate source were used with 3 processing conditions of the diet in a 2 x 3 factorial design. The pigs were blocked by weight (7.196 ± 2.03 kg BW) and then allotted randomly to 1 of 6 dietary treatments. Ten pens of 8 piglets each were fed with each dietary treatment. The two main processing conditions of the carbohydrate source were raw or extruded maize and the 3 processing conditions of the diet was meal or pelleted or extruded. No carbohydrate processing x diet processing interactions were observed (P > 0.05) for ADG, ADFI or FeR. In this experiment, extrusion of the maize led to an significant decrease in FeR efficiency (P < 0.05) (1.57 vs. 1.42) when compared to a raw maize diet. Pelleting a diet had no significant effect (P > 0.05) on ADG but tended to decrease ADFI (P < 0.07) and significantly improve FeR efficiency (1.49 vs. 1.66) when compared to a meal diet. Extruding the whole diet did not have any significant (P > 0.05) effect on ADG but tended to decrease ADFI (P < 0.07) and gave an significant improvement in FeR when compared to a meal diet (1.34 vs. 1.66). This processing technique also gave a significant improvement (P < 0.01) in FeR when compared to a pelleted diet (1.34 vs. 1.49). Experiment 2: The effect of pig feed processing conditions on pig metabolism parameters The effects of processing of the carbohydrate source and the diet on certain metabolism and production parameters of commercial Landrace x Large White pigs (n=24) were investigated. Two processing combinations of the carbohydrate source were used with 3 processing combinations in a 2 x 3 factorial design. Six diets were formulated on an iso-nutrient basis (14.48 MJ/kg metabolizable energy (ME), 23.01 crude protein (CP), 1.092% lysine, 0.742% methionine and cystine and 0.271% tryptophan on a DM basis). The pigs were blocked by weight (26.02 ± 0.25 kg BW) and then allotted randomly to I of 6 dietary treatments. The carbohydrate source was raw or extruded maize and the diets was meal or pelleted or extruded. No carbohydrate processing x diet feed form interactions were observed (P > 0.05) for dry matter intake (DMI), dry matter digestible energy (DE), Nitrogen (N) or dry matter intake (DMI). In a metabolism and nitrogen (N) balance study, apparent N digestibility, digestible energy and metabolizable energy contents were found not to be significantly (P > 0.05) influenced by carbohydrate or diet processing.
AFRIKAANSE OPSOMMING: Stysel is die hoof komponent in grane en is gewoonlik die primêre verskaffer van energie vir varke en pluimvee. Voermeulens kan verskeie metodes implementeer, insluitend fisiese behandeling soos bv. maal, verpilling en ensiem behandelings, om sel struktuur te verander. Maal en verpilling is die mees algemene prosessering metodes wat vir varkvoer gebruik word. Maar, verpilling van totaal geballanseerde voere is nie meer so ekonomies geregverdig nie as gevolg van stygende energie en masjinerie koste. Daarom moet die koste van voervervaardiging oorbrug word deur 'n verhoogde produksiedoeltreffendheid. Dit is al lankal bekend dat maal 'n voorvereiste is vir effektiewe vermenging van grondstowwe van 'n multi-komponent voer. Voerkoste verteenwoordig die hoof item van die koste van intesiewe diereproduksie. Voedingskudiges sal sonder twyfel voortgaan om voerprosessering te verfyn om so die koste van die rantsoen te verlaag en om die waarde van die rantsoen te verhoog vir die dier. Die moontlikhede is veelvuldig, maar die koste van elke ontwikkeling moet opgeweeg word teen verhoogde diereproduksie. Eksperiment 1: Die effek van voerprosesserings-tegnieke op speenvark groei en produksie 'n Proef is uitgevoer om die prosesseringseffek van 'n koolhidraat bron en voer op die groei van Landras x Groot Wit speenvarke (n=480) wat gespeen is op 28 ± 2 d te bepaal. Twee prosesserings-kombinasies van die koolhidraat bron en drie prosesserings-kondisies van die dieet is in 'n 2 x 3 faktoriaal ontwerp uitgevoer. Die varkies is geblok volgens massa (oorspronklik 7.196 kg ± 2 kg) en toe ewekansig in I van 6 dieët behandelings ingedeel. Die proefdiëte is vir lO hokke varkies gevoer, elke hok het 8 varkies in gehad. Die twee hoof prosesserings-kondisies van die koolhidraat bron was rou of gaar mielies en die drie prosesserings-kondisies van die dieët was meelof gaar of geëkstrueer. Geen koolhidraat prosesserings x dieët prosesserings interaksie van die dieët was opgemerk (P > 0.05) vir gemiddelde daaglikse toename (GOT), gemiddelde daaglikse voer inname (GDVI) of voer omset doeltreffendheid (VOD) nie. In die eksperiment was die VOD van die geëkstrueerde mielie dieët, statisties betekenisvol laer (P < 0.05) (1.57 vs.1.42) as die rou mielie dieët. Verpilling van die dieët het geen statisties betekenisvolle effek (P > 0.05) op GDV! gehad nie, maar die VOD was statisties betekenisvol (P < 0.05) beter (1.49 vs. 1.66) wanneer dit met die meel dieët vergelyk word. Ekstrusie van die dieët het geen statisties betekenisvolle effek op GOT en GOVI gehad nie, maar die VOD was statisties betekenisvol (P < 0.05) beter wanneer dit met die meel (1.34 vs. 1.66) en verpilde dieët (1.34 vs 1.49) vergelyk word. Eksperiment 2: Die effek van voer prosessering op vark metabolisme parameters 'n Eksperiment is uitgevoer op Landras x Groot Wit bere (n=24) om die effek van prosessering van 'n koolhidraat bron en voer te bepaal. Twee prosesserings-kombinasies van die koolhidraat bron en drie prosesserings-kondisies van die dieët is in 'n 2 x 3 faktoriaal ontwerp uitgevoer. Ses diëte is geformuleer op 'n iso-nutriënt basis (14.48 MJ/kg metaboliseerbare energie (ME), 23.01 ru-proteïen (RP), 1.092% lisien, 0.742% metionien and sistien en 0.271 % tryptofaan op 'n droeë materiaal (DM) basis). Die varke is geblok volgens massa en ewekansig aan 1 van 6 diëte toegeken. Die koolhidraat bron was gaar of rou mielies en die diëte was meel, verpil of geëkstrueer. Geen koolhidraat-prosessering x dieet interaksie is opgemerk (P > 0.05) nie. In 'n metabolisme en stikstof (N) balans-studie is daar gevind dat DM verteerbaarheid, skynbare N verteerbaarheid, verteerbare energie (GE) en ME inhoud nie beduidend deur die behandelings beïnvloed word nie.

The use of shrimp processing waste with other cheap raw materials such as cassava was studied as a potential low cost animal feed, specially in developing countries. The impact on the economies of the shrimp industry and possible effects on the environmental were taken into consideration in developing the project.

Beach-cast kelp (the most widely used feed for commercially grown South African abalone) is plentiful during winter months when periodic storms cause kelp to wash ashore. During summer, however, this resource is not always readily available and farmed abalone are often starved for short periods. The aim of this research was to assess how periodic kelp starvation influences growth of the commercially grown abalone, Haliotis midae Linnaeus.

I investigated the effect of turbidity on the foraging behaviour of juvenile Chinook salmon (Oncorhynchus tshawytscha) in the laboratory. Specifically, I examined a behavioural "tradeoff" between visual ability and "perceived" risk. I assessed visual ability by measuring the reaction distance of juvenile Chinook to planktonic Artemia prey. I found Chinook exhibited a log-linear decline in reaction distance with increasing turbidity. To determine the effects of turbidity and microhabitat on foraging rate, I conducted separate experiments for surface (Drosophila), planktonic (Artemia), and benthic (Tubifex) prey across a range of turbidity levels (0, 25, 50, 100, 200, 400, 800 mg•L⁻¹). Foraging rates were reduced at higher turbidity conditions for all three prey. However, for surface and benthic prey, foraging rates were also low in clear water; highest rates were attained at intermediate turbidity levels (50-200 mg•L⁻¹). The degree to which intermediate turbidities were associated with higher foraging rates was size-dependent. Smaller individuals (150-57 mm FL) exhibited relatively higher foraging rates in clear conditions than did larger individuals. However, planktonic foraging rates by juveniles were consistently high in clear water, regardless of fish size. In experiments manipulating light level independent of turbidity, I allowed salmon to forage under conditions which were either turbid, or clear but with light intensity correspondingly reduced. Foraging rates were similar between the two treatments for planktonic prey, but differed for benthic and surface prey. Generally, foraging rates exhibited by juvenile Chinook salmon could not be explained on the basis of visual ability alone. I suggest that young salmon also exhibited foraging behaviour consistent with their perception of risk to predation. In arena experiments, juvenile Chinook distributed themselves randomly in turbid conditions; in clear conditions they associated with the bottom. When bird and fish predator models were introduced the fish altered their spatial distribution, occupying deeper regions regardless of turbidity. However, their response in turbid conditions was less marked and lasted for a shorter time. Turbidity apparently mitigated the perceived risk of predation in juvenile Chinook. I developed a conceptual tradeoff model that predicted the general effect of turbidity on foraging behaviour. Assuming differences in either prey quality or perceived risk of predation in three microhabitats (surface, water column, bottom), the model resolved the apparent dissimilarities between planktonic and other foraging behaviours. Perceived risk of Chinook to predation was significantly different between surface and water column microhabitats. When exposed to a non-visual "fixed-risk" stimulus (sound), salmon apparently perceived less risk as turbidity increased. I conclude that in turbid waters juvenile salmon exhibit foraging behaviour in a manner consistent with a tradeoff between their visual ability and perceived risk.
Science, Faculty of
Zoology, Department of
Graduate

Many studies have been conducted on the effect of size-grading in other fish species. However, there is a paucity of scientific information on the effects of size variation on cannibalism of juvenile dusky kob. Thus, a study focusing on the effect of size variation on juvenile dusky kob aggressive and feeding (browsing) behaviours was conducted. Three separate groups of hatchery-reared juvenile dusky kob of were obtained from Oceanwise (Pty) Ltd for use in a series of three experimental trials. In all trials, juvenile fish of the same age were size-graded and the COV-value was used to determine the size variation. The focal fish (largest fish) was exposed to groups of fish with different size variation for 30-min. behavioural observations before and after feeding in randomised trials. The first experimental trial (Chapter 2) quantified the effect of increasing size variation and observation time on the aggressive and browsing behaviours of juvenile dusky kob. On average, juvenile dusky kob weighed 3.60 ± 0.68 g fish-1 and measured 5.8 ± 0.41 mm. Each focal fish was observed (a) before feeding in the morning, (b) 2 h after feeding, (c) 6 h after feeding and (d) 12 h after feeding. Fish increased browsing behaviours (averaging 6.60 ± 0.56) and decreased intimidating aggressive behaviours (18.60 ± 1.39) 12 h after feeding. Other aggressive behaviours occurred but did not differ between observation times. Aggressive and browsing behaviours positively correlated with size variation variables, predominantly, 12 h after feeding. An average frequency of 19 chases were observed positively correlated with size variation, followed by average frequencies of 17 body bites and browses, and 11 tail bites per 30 min. Some behaviours including average frequencies of 0.2 chases, 4 tail bites, 2.4 intimidating and 0.3 browsing behaviours negatively correlated with the size variation, generally closer to the last meal. These preliminary observations thus showed that fish have become hungry approximately 6-12 h after feeding and substituted certain behaviours for others as time after feeding passed and as size variation increased. The second experimental trial (Chapter 3) consisted of the observations further testing the relationship between aggressive behaviours and size variation of juveniles of dusky kob averaging 0.43 ± 0.27 g fish-1. The focal fish was exposed to groups of fish of four size variation (COV) treatments for observations before and 12 h after feeding. Aggressive behaviours positively correlated with size variation both before and 12 h after feeding. An average frequency of 437 body bites positively correlated more often with COV, followed by average frequencies of 365 intimidating behaviours and 199 tail bites per 30 min., respectively, before and 12 h after feeding. The least often exhibited aggressive behaviours averaged 26 chases while positively correlating with size variation on the times specified. An average frequency of 311 intimidating behaviours before and after feeding including average of 28 tail bites after feeding negatively correlated with size variation. This may relate to shift of behaviours depending on the needs and capacity of the fish. Apparently, aggressive fish can change its behaviour as a function of COV-values rather than the mean size of the other fish. The third trial (Chapter 4) investigated the effect of the aggressor’s (focal fish) size in relation its aggressive and browsing behaviours to other fish (non-focal fish). Juvenile fish used for this trial, on average, weighed 30 ± 7.63 g fish-1. Aggressive and browsing behaviours were observed in four treatments of a) high COV and mean weight below, b) low COV and mean weight less, c) high COV and mean weight equivalent to and d) low COV and mean weight higher than that of the focal fish. Increased frequencies of aggressive and browsing behaviours per 30 min. occurred in treatment A, sharing similar frequencies in treatment C, compared to the other treatments (B and D) which shared certain frequencies. The intimidating behaviours predominated, followed by browsing, body bites, chases and tail bites, respectively. The results of the overall study suggest that the time passed after feeding and increasing size variation and differences facilitated aggressive and browsing behaviours in juvenile dusky kob. Dusky kob showed increasing aggressive behaviours as early as in the first two weeks after hatching, averaging 0.43 ± 0.27 g fish-1 with the frequency correlating with size differences. Consistent size-grading technique in the same-age fish should be used to manage size variation associated with aggressive behaviours. The period of about 4-6 h after feeding may explain the noticeable increased aggressive and browsing behaviours. Thus, fish should be fed immediately before or after evacuation of their guts to maintain less-aggressive behaviours of juvenile dusky kob. Fish generally increased aggressive and browsing acts before and long time after feeding than closer to after feeding. The study has provided the fundamental scientific groundwork for fish farmers and future researchers can further explore size variation, time after feeding and gut evacuation rate as critical components of aggressive behaviours. The scientific knowledge of aggressive and cannibalistic behaviours has essential application in farming management to achieve improved survival and growth rates in juvenile fish.

Two experiments were conducted to determine the effect of dietary self-selection of protein and energy on the reproductive performance of Large White turkey hens. The first study examined the effect of self-selection on reproductive performance during a production cycle that started in July and ended in December. Hens were maintained on one of two dietary regimes for a 20-week production cycle. Control birds were fed a conventional diet (18% crude protein, 2700 kcal/kg) which contained nutrients at levels recommended by the National Research Council (NRC, 1984). The remaining hens were allowed to select their diet from two feed sources: one relatively high in protein and low in energy (35% crude protein, 1850 kcal/kg) and the other relatively low in protein and high in energy (8% crude protein, 3220 kcal/kg). Hens fed the split diet produced an equal number of eggs as control hens but consumed significantly less feed (p≤.05). The diet that was selected contained approximately 40% less protein than the control diet (p≤.001) which resulted in significantly increased efficiency of protein utilization (eggs/kg protein) for hens fed the split-diet (p≤.001). In addition, the incidence of broodiness was significantly reduced in the split-diet treatment (p≤.10). Egg weight, fertility, hatchability and hatch of fertile eggs were not significantly effected by the dietary regimes. There was significantly greater body weight loss in hens fed the split-diet (p≤.05). Increasing trends in feed, energy, and protein consumptions were noted over the course of production. For this reason a second experiment was conducted to determine if these trends were the result of seasonal affects, due to changing ambient temperatures, or the result of changes in nutrient requirements of the turkey hen occurring with different stages of production. The second experiment was similar to Experiment 1 except that the production period started in March and ended in July. As in the first experiment, egg production was equal for hens in the two treatment groups. Feed intake and energy intake were not significantly different for hens fed the split and complete diets. However, as in the previous experiment, protein intake was significantly reduced in the split-diet treatment (p≤.001). The incidence of broodiness was again attenuated among split-fed birds (p≤.10). Average daily feed and energy intake appeared to decrease over the course of production which was presumed to be related to increasing ambient temperatures. As in the previous experiment, protein intake increased over the course of production despite increasing environmental temperatures. Therefore, the increased protein selection noted in these two experiments does not seem to be related to hot weather and may indicate an increased protein requirement in the later stages of egg production. Based on the finding that the incidence of broodiness was reduced among hens fed the split-diet, blood sera from hens in both experiments were analyzed for luteinizing hormone (LH) and prolactin (PRL). Although the incidence of broodiness was significantly reduced among birds fed the split-diet, there was no significant difference in serum LH and PRL concentrations. Therefore, the reduction in the incidence of broodiness that was noted in these experiments was not correlated with changes in the blood concentration of these hormones.
Master of Science

Tydens embrio ontwikkeling groei weefsel deur selvermeedering, maar soos wat soogdiere volwassendheid nader vind groei net plaas deur sel vergroting. Volwassenheid word beskou as wanneer spiergroei ‘n maksimum bereik. Groei sluit die neerlegging van vet in, maar spiermassa is van primêre belang. Die groeikurwe (Fig 1) waarin massatoename teenoor ouderdom vergelyk word, volg ‘n sigmoidale kurwe (Owens et al, 1993). Onder ideale toestande is die groeitempo van lammers relatief konstant van kort na geboorte totdat die helfte van volwassemassa bereik word, waarna dit geleidelik afneem tot volwassenheid (Black, 1983). Die afname in groeitempo begin gewoonlik met die bereiking van puberteit (Owens et al, 1993).

An experiment was conducted with laying hens to evaluate the effects of added lysine, methionine and tallow on laying hen performances. Twenty-four treatments were obtained as a result of supplementing the basal diets, which contained either 13.86% or 13.5% protein, with 4 levels of synthetic L-lysine Hcl and with 3 levels of DL-methionine. Each treatment was fed to 5 neplicates of four birds each for ten 28-day periods. Tallow was added at a level of 4% to the 13.5% protein diet. Significant improvements were obtained in egg production and in egg mass as a result of lysine and methionine supplementation. However, 4% added tallow significantly decreased egg production and egg mass. On the other hand, tallow exerted positive effects upon the efficiency of feed utilization only when the diets were adequate in both lysine and TSAA. Three response criteria were used to measure the daily intake of lysine and total sulfur amino acids which are methionine and cysteine (TSAA) required by laying hens; percent egg production, egg mass, and plasma free lysine and TSAA levels. The pattern of response suggested that the dietary lysine requirements were 718 and 709 mg/hen/day for egg production and egg mass respectively; and the dietary TSAA requirements were 616 and 626 mg/hen/day for egg production and egg mass respectively. Multiple regression analysis, which related the intake of these amino acids with hen performances showed numerical, but non-significant, differences than the above requirement values. Using plasma free lysine and TSAA as criteria, the requirements for lysine and TSAA obtained from regression analysis were 674.8 and 561.6 mg/hen/day respectively. Feed intakes and protein intakes were not significantly affected by either lysine or methionine supplementation. However, 4% added tallow significantly decreased feed intakes and protein intakes.

Three experiments were conducted to study changes in exocrine pancreas function in relation to age, dietary fat and digestibility in poultry. In the first experiment, 120 White Leghorn and 120 Hubbard chicks were fed a basal diet with or without 5% animal fat. Total units of lipase, amylase, trypsin and chymotrypsin activities in pancreas increased linearly with age in Hubbards from 2 to 29 days, but plateaued after 16 days in Leghorns. Hubbards showed higher total pancreatic lipase, amylase, trypsin and chymotrypsin activities compared with Leghorns. Addition of 5% dietary fat significantly increased total lipase activity in pancreas, but decreased total amylase activity. Added fat had no well defined effect on total pancreatic trypsin and chymotrypsin activities. Fat digestibility in Leghorns fed the low fat diet increased significantly from 14 to 30 days of age, but not in Leghorns fed the high fat diet; while Hubbards fed both diets showed a significant decrease in fat digestibility. Fat digestibility was increased with added fat in both breeds. No direct correlation was found between nutrient digestibility and corresponding enzyme activity. In the second experiment, 80 young White Leghorn hens were fed a basal diet with or without 5% animal fat. Fat supplementation did not generally significantly affect lipase activities, but total lipase activity in pancreas decreased after 10.6 and increased after 12.7 mo in pancreata of birds fed both diets and fed the high fat diet, respectively. Fat digestibility was not affected by age, but was higher with fat supplementation. In the third experiment, 96 older White Leghorn hens were fed a basal diet with or without 5% animal fat. Total pancreatic lipase activity showed a U-shaped curve with the lowest value at 15.7 mo and increased after 15.7 mo following either natural or force molting. Fat supplementation did not significantly affect lipase activities. Amylase, trypsin and chymotrypsin activities decreased with age from 10.2 to 15.7 mo, but were increased with fat supplementation. Fat digestibility was not affected by age, but was significantly higher with fat supplementation.

Spexin (SPX), also called neuropeptide Q (NPQ), is a novel neuropeptide discovered recently using the bioinformatic approach. Except for mammals, SPX has not been reported in lower vertebrates including fish and amphibians. Following its discovery, the biological functions of this peptide in both higher and lower vertebrates are still largely unknown. To examine the structure and functions of SPX in fish model, molecular cloning of goldfish SPX has been performed and found to be highly comparable to its mammalian counterparts. In goldfish, broad expression of SPX transcripts has been found in various tissues. In vivo feeding studies have revealed that SPX mRNA levels in the telencephalon, optic tectum and hypothalamus of goldfish brain could be elevated by food intake. Brain injection of goldfish SPX, however, inhibited both basal and NPY- and orexin-induced feeding behaviour and food consumption. Similar treatment has also reduced transcript expression of NPY, AGRP and apelin with concurrent rises in CCK, CART, POMC, MCH and CRH mRNA levels in different brain areas examined. The differential effects of goldfish SPX on NPY, CCK and MCH transcript expression could also be noted in vitro in goldfish brain cell culture. In mice, SPX has been also found to be expressed within the brain-gut axis, including the stomach and specific neuronal subpopulations within the hypothalamus, including the ARC, PVN, DMN, and VMN. Similar to goldfish, feeding has shown to affect SPX mRNA and protein expression. Fasted animals have lower SPX mRNA in the stomach, and lower SPX protein levels in the serum and glandular stomach; the opposite effects have been noted in ad libitumfed animals. Both IP and ICV injection of SPX could produce a short-term feeding inhibitory effect. Furthermore, ICV administration of SPX could also downregulate hypothalamic expression of NPY, NPY5R, AGRP, and GHSR mRNA, and upregulate leptin receptor and MC4R gene expression concurrently. Taken together, these findings suggests that SPX may act as a satiety factor in vertebrate species. Apparently, SPX expression could be induced by feeding and the neuropeptide could act centrally to inhibit feeding by differentially regulating orexigenic and anorexigenic signals within the CNS.
published_or_final_version
Biological Sciences
Master
Master of Philosophy

Small maize livestock farmers in the Eastern Province of Zambia badly need forage high in protein to supplement the protein deficient pasture grass. Nutrient intake, especially for the small ruminants with small gastro-intestinal capacity compared to metabolizable energy requirement, will be near or below maintenance if these poor quality feeds are not supplemented. High quality supplements however, are beyond the reach of the small scale farmers. The effect of feeding maize husk and leucaena as a mixture or separately on voluntary intake of maize husk was studied over a 40 day period. Ten male goats with an average weight of 15 kg were used. In a separate experiment the effect of browse supplementation on maize husk utilization by goats was studied. The treatments were; maize husk plus urea; maize husk plus Leucaena leucocephala (3:2); maize husk plus Calliandra calothyrsus (3:2); and maize husk plus leucaena plus calliandra (3:1:1). The results of the study indicate that leucaena and calliandra are both potentially valuable feed components.

One hundred and eight Holstein dairy heifers were divided into two weight blocks based on beginning body weight (E = < 182 kg, light, > 270 kg, heavy). Heifers within weight blocks were randomly assigned to one of five treatments. Treatments consisted of three levels of NDF (35%, 45%, 55%) at 100% ofNRC TDN recommendation, and three levels of TDN (85%, 100%, 115 of NRC) at 45% NDF for light heifers. For heavy heifers, treatments consisted of three levels of NDF (40%, 50%, 60%) at 100% NRC TDN, and three treatments with similar levels of TDN at 50% NDF. Heifers were fed total mixed rations of corn silage, alfalfa haylage, ground orchardgrass hay, soybean meal, high moisture corn and a mineral mix formulated for 0.68 kg ADG. Mean gains (kg/d) were 1.07 and .96 for the light and heavy blocks, respectively. DMI as a percent of BWT differed across NDF levels for light heifers (3r'= 2.96, 2.56, 2.57, 2.57, and 2.87 % of BWT for the low, med., high NDF, and low, high TDN treatments, respectively). Heavy heifer DMI% did not differ (.Â¥= 2.45, 2.40, 2.24, 2.15, and 2.42 % ofBWT for low, med., and high NDF, and low, high TDN treatments, respectively). Equations to predict DMI were developed using intake information from this and a previous study. Backward stepwise regression was utilized to generate a simplified model. Model selected was: DMI (kg/d) = -5.9781 + (2.2120E-05 * BWTSQ) - (5.5527 * GAIN) + (2.7837 * GAINSQ) + (0.4668 * NDF) + (5.3930 * NDFSQ) + (0.03285 * DM) + 1 (7.7859E-03 * BWT * GAIN);11 = 514, rz = .67.
Master of Science

Lupin seed has the potential to be used as a protein supplement in ruminant rations, but its usage is restricted by the presence of alkaloids. Experiments were conducted with the aim of determining whether the removal of specific toxic alkaloids, lupanine and 13-hydroxylupanine, from crushed lupin seed (CLS) would improve the organic matter intake (OMI) and average daily gains (ADG) in lambs, and also improve the lactation performance in dairy cows. Effects on liver function in lambs were also investigated. An additional study on the effects of the detoxification of CLS on the degradation of protein was conducted. In Experiment 1, 30 growing Corriedale lambs were fed five diets for 105 d according to a randomized complete block design (RCBD) with six blocks. Two diets contained intact CLS at 15% (LUI-15) or 30% (LUI-30) of DM; two other diets contained detoxified CLS at 15% (LUD-15) or 30% (LUD-30) and the control (CON) diet was supplemented with crushed sunflower seed, which was locally prepared, on-farm. All diets were formulated to be isonitrogenous (16% CP). The alkaloid content (lupanine and 13-OH lupanine) of the diets was.31,.70,.21 and.52% for LUI-15, LUI-30, LUD-15 and LUD-30, respectively. Thus, diets containing detoxified CLS contained approximately 30% less alkaloids than those with intact CLS. Estimates of ADG of lambs fed diets containing detoxified CLS was higher (P $<$.01) (120 g.d$ sp{-1}$) than that of lambs fed intact CLS (76 g.d$ sp{-1}$). The OMI (73 g/Wkg$ sp{0.75}$) was also higher, although not significantly, for lambs fed diets containing detoxified CLS. Feed conversion efficiency was increased (P $<$.05) by the detoxification of CLS. Lambs fed diets containing intact CLS consumed more OMI as time progressed, suggesting that adaptation to CLS might have occurred. Lambs fed diets containing intact CLS demonstrated increased trends in the activity in plasma of the enzymes glutamic oxaloacetic transferase (GOT) and $ gamma$-glutamyl transfer

Four successive groups of four calves each (~ 4 mo old) were individually penned and observed during a 14 d trial period for choice of concentrate. Prior calf diets contained soybean meal (SBM) (for two groups and distillers grains in place of SBM for two groups. Concentrates contained approximately equal amounts of corn with either SBM, peanut meal (PNM), fish meal (FSM), or corn gluten meal (CGM). Each day of four trials, .45 kg of each concentrate was randomly assigned to one of four equal feed box sections. Calf feeding position was recorded every 30 sec for no more than 50 min or until calves stopped eating. In addition, 1.36 kg of first cutting orchardgrass hay was offered twice per day. Measurements of amount of each feed consumed, order of consumption and length of time spent eating each feed were analyzed statistically to determine preference. Overall preference was for SBM, closely followed by PNM, both over FSM and CGM, with the l preference status of FSM showing the most change over time by decreasing throughout the trial periods. Neither section in which feed was offered nor previous experience with SBM significantly influenced preference. In addition, twenty calves ranging in age from 4 mo to 7 mo were divided and housed in four groups of five and observed during a 30 d trial period for acceptability of the protein feeds tested for preference. Acceptability, measured subjectively as length of time required by calves to eat each feed, was greatest for SBM, closely followed by PNM and CGM, and least for FSM. Analysis of calf weight gain showed no differences between feeds.
Master of Science

A laboratory assessment and three in vivo trials were conducted to measure the nutritive value of whole soybeans subjected to various methods of heat treatment. No significant differences were found for ADG and feed conversion ratio. There was a significant reduced proportion of saturated-to unsaturated fatty acids in the loin eye area of pigs fed whole soybean products, when compared to soybean meal control. Extruded whole soybeans resulted in a lower degree of unsaturation than the other heat treated whole soybeans. Whole soybean products were evaluated for their digestibility in weanling (21 days) piglets. Feces were collected daily during two 5-day periods. It was found that the ether extractable portion of extruded whole soybeans has a higher digestibility than that of the remaining four soybean treatments. It was also found that CP is more digestible in animals at 6 weeks of age than in animals at 4 weeks of age. In conclusion: heat treated whole soybeans do not adversly affect the performance of weaners nor that of growing and finishing pigs, even at high dietary levels (25%). Feeding whole soybeans results in a higher degree of unsaturation in the carcass. The EE fraction of extruded whole soybeans is more digestible than whole soybeans of other heat treatments. (Abstract shortened by UMI.)

The feeding biology of three euphausiid species, Euphausia vallentini (adults and juveniles), E. longirostris and Nematoscelis megalops was investigated during austral autumn (April/May) of 1998 and 1999, in the vicinity of the Prince Edward Islands (Southern Ocean). Data on the abundance and biomass of these species, estimated from bongo net tows, were investigated. Trophic position was assessed using gut contents and stable nitrogen isotope measurements. Feeding rate and daily carbon ration were estimated using the gut fluorescence and the gut fullness techniques. Vertical migrations into the surface waters at night were found to be strong for Euphausia vallentini adults and juveniles. Associated with these migrations were clear diel feeding patterns. Insufficient data during daylight hours for E. longirostris made it impossible to determine diel feeding patterns, but high feeding activity did occur during dark hours. Nematoscelis megalops did not show any distinct diel feeding pattern, but slightly higher gut fullness indices in the late afternoon suggested that feeding activity may have been highest during this period. For both Euphausia spp. high gut pigment levels were recorded in 1999, which corresponded to higher ambient chlorophyll a concentrations for that year. Highest initial gut pigment levels and highest ingestion rates were found for Euphausia longirostris in both years and lowest values were observed for N. megalops. High phytoplankton and low metazoan contributions to the diet of Euphausia vallentini juveniles, as shown in the gut content analysis, and low stable nitrogen isotope ratios (ð¹⁵N = 1.39±0.31), both indicated that this group was principally herbivorous. The results of gut content analysis of the adults of E. vallentini were similar to those of the juveniles, however, stable nitrogen isotope results showed that there was a higher degree of omnivory (ð¹⁵N = 3.81±0.66). Daily ration estimates from the gut fluorescence and fullness techniques showed that between 3.3 and 25.7 % of E. vallentini adults total daily carbon ration was derived from autotrophic sources. Although the contribution of carnivory to the diet was difficult to determine, the adults of this species may be considered omnivorous. Irrespective of the degree of carnivory, a dietry shift with an increase in size was evident for this species. Gut content analysis for Euphausia longirostris showed that this species consumed large amounts of both phytoplankton and metazoan prey and this was reflected in the stable nitrogen isotope results (ð¹⁵N = 6.88±0.60). These findings were supported by the results of the daily carbon ration estimates which showed that autotrophic carbon contributed between 6.9 and 20.3 % of the daily carbon consumption. The gut content analysis suggested that N. megalops was omnivorous, and the stable nitrogen isotope results place it in a trophic position equivalent to that of E. longirostris (ð¹⁵N = 6.83±0.78). Calculations from daily ration estimates suggested that only 3.1 % in 1998, and 3.2 % in 1999, of the carbon ingested was of autotrophic origin. This species may therefore be considered carnivorous. Implications of the findings of this study are discussed in terms of carbon cycling in the Southern Ocean.

Foraging by captive individuals of three species of towhees (Pipilo:Emberizinae) was investigated to determine if patch choice was associated with critical threshold levels of foraging success. Birds were offered a choice of feeding in three litter types. Once individual preferences for litter type were determined, I reduced the amount of food (millet seed) under a preferred litter each day, while maintaining high levels under a non-preferred litter. Thus, birds experienced a declining resource gradient under their preferred litter. During the bird's initial foraging period each day, I noted number of seeds taken and number of double-scratches made in each litter type, until the bird abandoned its preferred litter and shifted to the other patch. Foraging theory assumes that patch choice is made when foraging success declines as resources decline to some threshold level. I estimated success using information potentially available for decision-making by the birds. One of four success variables, mean seeds/scratch, best conformed to the expected pattern, providing supportive evidence for the threshold assumption. The three species changed patches at species-specific thresholds. Pipilo fuscus, a foraging generalist, switched to its non-preferred litter when food levels under the preferred litter were high. Pipilo aberti and P. erythrophthalmus, two foraging specialists, foraged in their preferred litters until food levels were much lower. Optimal Foraging Theory predicts that shifts in patch use are determined by between-patch comparisons of foraging success. Timing of towhee patch changes was not consistent with between-patch comparisons. An alternative expectation theory, Status-quo Foraging, which emphasizes comparisons of within-patch success, was more consistent with observed results. The rapid patch switching shown by P. fuscus may reflect greater flexibility of this species' foraging repertoire in its natural habitat. This result suggests that foragers with imperfect knowledge may use recent past experience to make foraging decisions. Optimal Foraging Theory provided a useful null model for comparing foraging theories. Deviations from predictions indicated how more realistic hypotheses can be constructed. The nature of available information plays an increasingly important role in modeling decision-making by imperfect foragers.

Thesis (MSc)--Stellenbosch University, 2000.
ENGLISH ABSTRACT: South Africa, like many other developing countries throughout the world, has a rapidly growing human population, resulting in a consequent increased demand for food. Ironically, this increased food supply has to be produced on a smaller area of available agricultural land, which means that agricultural production processes have to become more efficient. Furthermore, the majority of the people in these countries are unschooled and poverty is a common phenomenon. Therefore, animal scientists are faced with the challenge and the responsibility to provide affordable, high quality food to these people. One way of reaching this objective is to improve the utilisation of low-quality, high roughage feedstuffs like crop residues and dry natural grass pastures. In the winter rainfall area of South Africa alone, about 460 000 ha of wheat straw are annually available. The ruminant animal has the ability to utilise the relatively unavailable energy (cellulose, hemi-cellulose and pectin) in the fibre component of these low-quality forages. Unfortunately, various factors, of which a N deficiency is the pre-dominant one, limit the utilisation of these feedstuffs. If the ability of the ruminant to utilise low-quality, fibrous energy sources is improved, these abundantly available and relatively inexpensive crop residues and natural pastures can be converted into high quality protein food for human consumption. Therefore, in order to rectify the N deficiency caused by these low-quality forages, the supplemental N requirement to optimise the fermentation and digestive processes of the ruminant animal has to be determined. The first study was conducted to determine the supplemental rumen degradable protein (RDP) requirement, to maximise the digestible organic matter intake (DOMI) of Dohne Merino sheep fed wheat straw. Keeping the high cost of natural protein supplementation in mind, the purpose of the second study was to determine the amount of true protein that can be replaced by nonprotein nitrogen (NPN) in RDP supplements fed to Dohne Merino sheep consuming wheat straw. In both trials animals had ad libitum access to low-quality wheat straw (3.2% CP; 74.2% NDF) and water. In the first trial, RDP (calsium caseinate: 90% CP; 100% rumen degradable) was intraruminally administered at 07hOOand 19hOO,at the following levels: 0, 40,80, 120 and 160 gld. Intake, fermentation and digestion were monitored to determine the RDP requirement to maximise DOM!. Digestible organic matter (OM) intake displayed a quadratic increase with elevated amounts of RDP (P < .01), and was maximised at an estimated 3.15 g RDPlkg BW·75 or 11.6% of DOM. Forage OM intake tended to increase quadratically (P = .15) with higher RDP levels. Microbial nitrogen (MN) flow to the duodenum and microbial efficiency increased quadratically (P ~ .04) and fluid dilution rate tended to increase in a quadratic manner (P = .15) with increased RDP supplementation levels. Rumina! ammonia nitrogen (NH3-N) and total volatile fatty acid (VFA) concentrations increased linearly (P ~ .07), while rumen pH exhibited a variable response to increased RDP levels (cubic; P = .08). Increasing RDP supplementation to Dohne Merino wethers consuming wheat straw, generally enhanced forage utilisation and DOM!. In the second trial, urea replaced different levels of casein N on an isonitrogenous basis, ranging from 0 - 100%. Since true protein is much more expensive than urea, the purpose of this study was to determine the maximum natural protein level that can be replaced by urea in RDP supplements, without adversely affecting intake and/or fermentation and digestive processes. The control treatment provided all of the RDP in the form of calcium caseinate (90% CP; 100% rumen degradable). The percentages of supplemental RDP from urea in the other treatments were 25, 50, 75 and 100%. The 100% urea treatment was balanced with maize starch to contain 40% CP and all other treatments received the same amount (150 gld) of starch. Intake of forage OM showed a weak decreasing trend (linear; P = .16) with increasing urea levels. Ruminal digestibilities of OM and NDF were not affected (P ;;::.:18) by urea level. Increasing urea levels resulted in linearly reduced total tract OM and NDF digestibilities (P ~ .10). As a result, DOMI declined (linear; P < .01) with increasing proportions of urea. Effects of increasing urea proportions on duodenal N flow, microbial efficiency and fluid dilution rate were minimal. Ruminal NH3-N tended to increase quadratically with increasing urea levels (P = .l4). Total VFA concentration decreased linearly (P = .03), while rumen pH increased in a linear manner (P = .08) with increasing urea proportions. Branched-chain volatile fatty acids (BCVFA's) and valerate decreased linearly (P ~ .05) with increasing urea levels, while other VFA's and the acetate:propionate ratio were generally not affected by treatment (P ;;:::.16). It appears as though ruminal and total tract OM and NDF digestibility criteria, as well as DOMI reached maximum values at substituting 25% of casein for urea. It is therefore concluded that replacing 25% of casein with urea in RDP supplements, will maintain effective utilisation of low-quality forages by sheep.
AFRIKAANSE OPSOMMING: Ontwikkelende lande, insluitend Suid-Afrika, word gekenmerk deur 'n vmmge bevolkingsaanwas. Dit lei tot 'n verhoogde vraag na voedsel, wat op 'n gevolglik kleinerwordende beskikbare kommersiële lanbbou-area geproduseer moet word. Die doeltreffendheid van produksieprosesse in die landbousektor moet dus noodgedwonge verbeter word. Die oorgrootte meerderheid van die bevolkings in ontwikkelende lande is ongeletterd en armoede en hongersnood is soms 'n algemene verskynsel. Veekundiges word dus gekonfronteer met die uitdaging en verantwoordelikheid om bekostigbare, hoë kwaliteit voedsel aan hierdie mense te voorsien. Een van die mees doeltreffende metodes om hierdie probleem aan te spreek, is om die benutting van lae kwaliteit, hoë-vesel voerbronne, bv. oesreste en droë grasweidings te verhoog. In die winterreënstreek van Suid-Afrika alleen, is 460 000 ha koringstrooi jaarliks beskikbaar. Herkouers beskik oor die besondere vermoë om die relatief onbeskikbare energie (sellulose, hemi-sellulose en pektien) in die veselkomponent van hierdie lae kwaliteit voere te benut. Verskeie faktore, waarvan 'n N-tekort die mees prominente is, beperk egter die benutting van hierdie voerbronne. Die uitdaging is dus om die herkouer se vermoë om hierdie voere te benut, te optimaliseer. Sodoende word 'n geredelik beskikbare, onderbenutte en relatief goedkoop voerbron omgeskakel in hoë kwaliteit proteïen vir menslike gebruik. Die N-aanvullingsbehoefte om die fermentasie- en verteringsprosesse van die herkouerdier te optimaliseer moet dus bepaal word, sodat die N-tekort in herkouers, wat soortgelyke weidings benut, reggestel kan word. Gevolglik was die doel met die eerste proef om die behoefte aan rumen degradeerbare proteïen-(RDP)-aanvulling, vir die maksimum inname van verteerbare organiese materiaal (VOM) van Dohne Merino skape wat koringstrooi ontvang, te bepaal. Weens die hoë koste van natuurlike proteïenaanvulling, was die doel met die tweede proef om die hoeveelheid ware proteïen in RDP-aanvullings, vir Dohne Merino skape wat koringstrooi ontvang, wat met nie-proteïen stikstof (NPN) vervang kan word, te bepaal. In beide eksperimente het die diere ad libitum toegang tot koringstrooi (3.2% RP; 74.2% NBV) en water gehad. In die eerste proefis RDP (kalsiumkaseïnaat; 90% RP; 100% rumen degradeerbaar) teen 07hOOen 19hOOintraruminaal toegedien, teen die volgende peile: 0, 40, 80, 120 en 160 gld. Inname, fermentasie en vertering is gemonitor om die RDP behoefte vir die maksimum inname van VOM te bepaal. Verteerbare OM-inname het 'n stygende kwadratiese tendens (P < .01) getoon met verhoogde RDP-peile en het 'n maksimum bereik by 'n aanvullingspeil van 3.15 g RDPlkg metaboliese liggaamsmassa (LM·75 ) of 11.6% van VOM. Organiese materiaalinname vanaf koringstrooi het geneig om kwadraties toe te neem (P = .15) met verhoogde RDP-peile. Mikrobiese stikstof-(MN)-vloei na die duodenum en mikrobiese effektiwiteit het kwadraties toegeneem (P :::;.;04) en vloeistof deurvloeitempo het 'n neiging vir 'n kwadratiese toename (P = .15) met verhoogde RDPpeile getoon. Rumen-ammoniakstikstof (NH3-N) en vlugtige vetsuur-(VVS)-konsentrasies het lineêr toegeneem (P :::;.;07), terwyl rumen pH 'n wisselende reaksie (kubies; P = .08) met stygende RDP-peile getoon het. Verteerbare OM-inname en benutting van koringstrooi is verbeter deur stygende peile van RDP aanvulling by Dohne Merino hamels. In die tweede proef is kaseïen op 'n iso-stikstof basis met verskillende ureumpeile, vanaf o - 100%, vervang. Omdat ureum baie goedkoper is as natuurlike proteïen, was die doel van die tweede proef om die hoeveelheid natuurlike proteïen in RDP-aanvullings te bepaal wat met ureum vervang kan word, sonder om inname, fermentasie en vertering te benadeel. Die kontrolebehandeling het 100% van die RDP in die vorm van kalsiumkaseïnaat (90% RP; 100% rumen degradeerbaar) voorsien, terwyl ureum in die ander behandelings onderskeidelik 25, 50, 75 en 100% van die kaseïen-N vervang het. Die 100% ureumbehandeling is met mieliestysel tot 40% RP gebalanseer en dieselfde hoeveelheid stysel (150 gld) is by al die ander behandelings ingesluit, om moontlike effekte van stysel op rumenfermentasie te elimineer. Organiese materiaalinname vanafkoringstrooi het 'n swak dalende tendens getoon met stygende ureum insluitingsvlakke (lineêr; P = .16). Rumenverteerbaarheid van OM en neutraal bestande vesel (NBV) is nie deur die ureumpeil beïnvloed nie (P ;;:: .18). Toenemende ureumpeile het gelei tot 'n lineêre afname in totale kanaal OM en NBVverteerbaarheid (P ~ .10). Gevolglik het VOM inname lineêr afgeneem (P < .01) met stygende ureum insluitingspeile. Die effek van behandeling op duodenale N-vloei, mikrobiese effektiwiteit en vloeistof deurvloeitempo was minimaal. Rumenammoniakstikstof-( NH3-N)-konsentrasie het 'n stygende kwadratiese tendens getoon (P = .14) met toenemende ureum peile. Totale vlugtige vetsuur-(VVS)-konsentrasies het lineêr gedaal (P = .03), terwyl rumen pH lineêr toegeneem het (P = .08) met stygende ureum insluitingsvlakke. Vertakte ketting VVS' e en valeriaansuurkonsentrasies het lineêr gedaal (P ~ .05) met stygende ureumpeile, terwyl die ander VVS' e en die asynsuur:propioonsuurverhouding oor die algemeen nie deur behandeling beïnvloed N; nie (P ;;:: .16). Dit blyk asof VOM inname, sowel as rumen- en totale kanaal verteerbaarheidsmaatstawwe, by 25% vervanging van kaseïen-N met ureum-N 'n maksimum bereik het. Die gevolgtrekking is gemaak dat die doeltreffende benutting van lae kwaliteit ruvoere deur skape, gehandhaaf sal word deur 25% van die ware proteïen in RDP-aanvullings met ureum te vervang.

Thesis (MScAgric)--University of Stellenbosch, 2002.
ENGLISH ABSTRACT: The Dorper is numerically the second most abundent of all the sheep breeds in South Africa. It is the most numerous sheep breed in the dry arid areas of South Africa which make out a very big portion of the natural grazing in South Africa. In this study the feedlot performance was specifically investigated since so little research has been done in this regard. In the first study (Chapter 1), the production efficiency, body components and commercial yield of 13 Dorper and 12 Merino lambs were investigated. A pelleted diet was fed ad lib and the water intake per day was measured. Lambs were slaughtered at 30kg and at 40kg live weight and cut up according to the South African commercial cuts. The weights of the organs, head, feet, skin and carcass were also recorded. Results from the first study showed that Dorpers had a lower (P<0.05) water efficiency (285.97 mVkgO75/day) than the Merinos (240.07 mVkg075/day), but had a higher (P<0.05) nitrogen retention. The head, feet, skin, heart, lungs, kidneys and diaphragm of Merino lambs were heavier (P<0.05). Merinos had heavier (P<0.05) breast and shank and thick rib (only at 40kg live weight) cuts. But the Dorper had a significantly heavier hindquarter (buttock and loin) which is the high-priced cut of any carcass. It seems that the Dorper will do well under feedlot conditions, and would possibly make a better commercial meat producer than the Merino under all circumstances. In the second study (Chapter 2), the free-ranging Dorper on natural grazing were compared with 7 Dorper lambs in the feedlot study. The essential amino acids in the duodenal contents were compared. The free-ranging Dorpers were randomly slaughtered at 40 kg live weight and a duodenal sample was collected. The feedlot Dorpers were also slaughtered at 40 kg live weight and a duodenal sample was taken. The second study indicated no significant differences between the EAA composition of the duodenal samples, whether protein quantity was taken into account (gAA/100g crude protein (CP)) or not (expressed as % of lysine). The chemical scores indicated that the two most limiting amino acids in the duodenal digesta for whole empty body growth were: arginine and histidine. Excess levels of amino acids tend to be present in all three duodenal digesta samples (isoleucine, leucine, lusine, methionine, phenylalaline, threonine and valine). The whole empty body EAA composition (g AA/100 g crude protein) was as follows 7.10 arginine; 2.40 histidine; 3.31 isoleucine; 7.22 leucine; 6.61 lysine; 1.62 methionine; 3.91 phenylalanine; 3.77 threonine and 4.85 valine. The composition can serve as an example of the ideal EAA requirements for whole empty body growth between 30 and 40 kg live weight of Dorper ram lambs. The duodenal amino acid concentrations of the free-ranging Dorper compared well with those of the feedlot Dorpers which suggests that the microbial organisms have a big influence on the amino acid concentration which reaches the intestines.
AFRIKAANSE OPSOMMING: Die voerkraal prestasie en essentiele aminosuur behoeftes van groeiende Dorper lammers: The Dorper is getalgewys die tweede mees talryke skaapras in Suid-Afrika. Dit is die mees talryke skaapras wat in die drce woestynagtige gebiede van Suid-Afrika aangetref word. Die gebiede beslaan die grootste oppervlakte van Suid-Afrika se natuurlike weiveld. In die studie is voerkraal prestasie van die Dorper nagevors, spesifiek omdat daar so min navorsing op hierdie gebied gedoen is. In die eerste studie (Hoofstuk 1) is die produksie doeltreffendheid, liggaams komponente en kornrnersiele produksie van 13 Dorper- en 12 Merino lammers ondersoek. 'n Verpilde rantsoen is ad lib gevoer en die water inname per dag is ook gekontroleer. Die lammers is geslag op 30 en 40 kg lewende gewig en die karkasse is daarna opgesny volgens die Suid-Afrikaanse kornmersiele karkassnitte. Die resultate van die eerste studie het getoon dat Dorpers 'n laer water potentiaal (P<0.05) (285 97 mflkgO 75/dag) as die Merinos (240.07 mVkg075/dag) het. Dorper lammers het ook 'n hoer (P<0.05) stikstof retensie. Die kop, vel, pote, hart, longe, niere en diafragma van Merino lammers was swaarder (P<0.05). Merinos se brisket en dikrib snitte weeg ook swaarder (P<0.05). Die Dorper het 'n beduidende swaarder agterkwart (len de en boud) gehad, wat die duurste snit is van enige karkas. Die Dorper het baie goed gedoen in die voerkraal toestande en sal waarskynlik onder aile omstandighede 'n hcer vleisproduksie op die Merino lewer. In die tweede studie (Hoofstuk 2), is die vryweiende Dopers op natuurlike weiding vergelyk met die Dorpers in 'n voerkraal. Die twee groepe Dorpers se essensiele aminosuur samestelling in hul dunderms is bepaal en vergelyk om te bepaal of daar enige tekorte teenwoordig is. Die Dorpers in die veld en in die voerkraal is op 40 kg lewende gewig geslag en monsters van die dunderm inhoud is gekollekteer. Die monsters is ontleed om te bepaal of daar enige betekenisvolle verskille in die essensiele aminosure van die dunderm inhoud tussen die veld Dorpers en voerkraal Dorpers was. Die tweede studie het geen betekenisvolle verskille getoon tussen die dunderm monsters se essensiele aminosure, of die hoeveelheid proteien (gAA/100g) in aanmerking geneem is of nie (uitgedruk as % lisien). Die chemiese telling dui aan dat die twee mees beperkende aminosure in die dunderm inhoud vir lee liggaam groei arginien en histidien was. Oormaat vlakke van aminosure kom voor in al drie dunderm inhoud monsters (isoleusien, leusien, lisien, metionien, femielalanien, treonien en valien). Die totale lee liggaam essensiele aminosuursamestelling (g aminosuur/100g ruprotein) was soos volg: 7.10 arginien; 2.40 histidien; 3.31 isoleusien; 7.22 leusien; 6.61 lisien; 1.62 metionien; 3.91 fenielalanien; 3.77 treonien en 4.85 valien. Hierdie aminosuursamestelling kan as 'n aanduiding dien vir die ideale aminosuurbehoeftes van Dorper ram lammers vir totale lee liggaamsgroei vanaf 30 tot 40 kg lewende massa. Die dunderm aminosuur konsentrasie van die Dorper in die veld stem goed ooreen met die van die voerkraal Dorper. Dit toon waarskynlik dat die mikrobe organismes in die rumen In groot invloed het op die aminosuur samestelling wat die dunderm bereik.

Thesis (Mnutr)--Stellenbosch University, 2003.
ENGLISH ABSTRACT: INTRODUCTION Many patients seen by dietitians in Tygerberg Academic Hospital require feeding via the enteral route. Prior to this study all enteral feeds were mixed individually by hand, and production was time consuming and very labour intensive. The purpose of this study was, therefore, to compare the current method of production, with mechanised bulk production (MP) and "Ready to hang" (RTH) products, taking time, safety and cost effectiveness into consideration. MATERIALS AND METHODS A machine was designed and built to produce and decant bulk volumes of enteral feed. Production methods were evaluated and data was obtained regarding the time taken to produce a feed, and the true cost of the feeds produced. Microbiological samples were collected and the safety of all the three systems was determined and compared. RESULTS MP production time was significantly longer than hand production (HP), but MP decanting was significantly more accurate. RTH feeds cost 152% more than HP feeds, and MP feeds cost 95% of HP feeds. Seventy-one per cent of HP feeds, 74% of MP feeds and 34% of RTH feeds were contaminated just after administration had began. CONCLUSIONS Mechanisation is less labour intensive than HP and helps to decrease total costs. RTH feeds quickly become contaminated after administration decreasing their other advantages.
AFRIKAANSE OPSOMMING: IN L E ID IN G Baie van die pasiente wat deur dieetkundiges in Tygerberg hospitaal gesien word, benodig buisvoedings. Vo or hierdie studie geloots was, was alle buisvoedings by Tygerberg hospitaal met die hand gemaak. Hierdie metode is baie tydsaam en arbeidsintensief. Die doel van hierdie studie was, om die voorlopige sisteem van produksie te vergelyk met gemeganiseerde grootmaat produksie en "ready to hang" (RTH). Die studie het die volgende in ag geneenv produksietyd, mikrobiologiese veiligheid en koste effektieweteit. METODE 'n Masjien was ontwerp en gebou om grootmaat buisvoedings aan te maak en aftegiet. Produksie metodes was geevalueer en inligting bymekaar gemaak met betrekking tot produksietyd, en die ware koste van die voedings. Mikrobiologiese monsters was versamel en die mikrobiologiese veiligheid van al drie sisteme is bepaal en vergelyk. RESULTATE Produksie met die masjien was betekenisvol longer as die voedings wat met die hand gemaak was, maar die masjien het betekenisvol meer akkuraat afgemeet met afgiet. RTH voedings se koste beloop 152% meer as voedings wat met die hand gemaak word, en voedings wat deur die masjien gemaak word kos 95% van die wat met die hand gemaak is. Een en sewentig persent van die voedings wat met die hand gemaak was, 74% van die masjiengemaakte voedings en 34% van die RTH voedings was besmet net na toediening begin was. GEVOLGTREKKINGS Meganisasie is minder arbeidsintensief as voedings wat met die hand gemaak is en help om die kostes af te bring. RTH voedings word vinnig besmet met organismes na die begin van toediening en dit verminder hulle ander voordele.

The three components of the aerobic respiratory metabolism of sablefish, digestion (SDA), activity, and standard metabolism, were examined separately and together as dependent variables responding to the independent variable, feeding frequency. All fish were similar in size and held within a temperature range of 8.5 - 9.5 C on a 12 hr photoperiod. Fish were studied in both 4000 L mass respirometers equipped with activity meters and in a tunnel respirometer. Identical meals were given every 4, 7, and 14 days. A fourth series of starved fish served as controls. In the mass respirometers, oxygen consumption, ammonia nitrogen excretion, and activity were monitored continuously before, during, and after acclimation to the different feeding frequencies. This permitted estimation of total metabolism, the activity and feeding components of total metabolism, standard metabolism, and protein and lipid catabolism. In the tunnel respirometer, energy expenditures at similar levels of Imposed activity were compared before and after eating to examine repartitioning of locomotor and feeding metabolism. It was found that swimming energy expenditures and standard metabolism are a sigmoid functions of ration frequency. The lowest metabolic rates are associated with the least frequent feedings and the greatest with the most frequent meals. Consequently, total and routine metabolic rates are also direct functions of ration history. The lowest metabolic rates are based on lipid oxidation as an energy source. The fish primarily oxidize proteins to meet metabolic needs when on higher rations. It is also shown that apparent specific dynamic action (SDA) results to a greater extent from catabolic rather than anabolic processes. When the dual metabolic load of locomotion and digestion threatens to exceed the aerobic metabolic scope of the fish, a physiological mechanism exists whereby oxygen supply is preferentially shunted to locomotor requirements. When spontaneously active in the mass respirometers, the activity component of metabolism is generally less than 25% of the standard metabolic rate and digestion and locomotion can proceed synchronously. When swimming spontaneously, the sablefish move at a single, probably optimal velocity regardless of ration history. The better fed fish in the experiments were active most of the day despite the low contribution of the activity component to the routine metabolic rate. These results have significance regarding assumptions often made in bioenergetic models, specifically that activity energy expenditures and standard metabolic rates are independent of ration. They reveal an adaptable physiology which applies different energy partitioning strategies to meet the changing metabolic needs of fish in a dynamic environment with a variable food supply.
Science, Faculty of
Zoology, Department of
Graduate

Data from the University of New Hampshire were used to analyze dry matter intake and milk production in Holstein dairy cows. Equations predicting 4% FCM and dry matter intake were derived from this data using ordinary least squares. Days in milk, available nutrients, calving date, and previous period 4% FCM accounted for 90% of the variation in 4% FCM for heifers and 93% of the variation in 4% FCM for cows with previous lactations. Days in milk, acid detergent fiber, calving date, and dry matter intake from the previous 28 day period accounted for 71% of the variation in heifer dry matter intake and 79% of the variation in dry matter intake for the older cows. First period dry matter intake was predicted from first period 4% FCM, cow body weight, and acid detergent fiber of the ration. The lower R² for the first period dry matter intake (41% for heifers and 43% for cows with previous lactations) indicated that dry matter intake for a cow within a lactation was much more predictable than dry matter intake between different cows. Rations were balanced for absolute amounts for simulated lactating cows using NRC requirements and 4% FCM and dry matter intake generated from the prediction equations. Relationships between 4% FCM and nutrient concentrations were determined for heifers and multiparous cows. These recommendations suggest maximum feeding of nutrients to groups producing at least 35 kg of 4% FCM daily. The effect of grouping and individual feeding on 4% FCM were analyzed. Independent variables included nutrient concentration, dry matter intake, groups, calving interval, variability of 305 day milk production within the herd, and level of feeding. Holding dry matter intake and nutrient concentrations constant, increasing the number of groups from one to two increased 4% FCM by 0%-3%, two groups to three groups by 0-2%, and three groups to four groups by 0-1%. Changing from one group to individual feeding increased 4% FCM by 2%-4% and two group to individual feeding increased 4% FCM by 0%-3%. The range of figures was influenced by herd production level, calving interval, and variability of within herd production. High variability of production favored additional groups, while high calving intervals favored individual feeding. To estimate expected change in profitability due to a change in grouping or feeding methods, multiply previous milk revenue by expected percentage change and subtract the increased cost of feeding. Feeding less than the group average for nutrients was not found conducive for increasing profitability. In fact, production response to protein suggested that the low producing groups in multiple group feeding systems should be increased in protein slightly. Individual feeding had the most potential for profitability, although group feeding compared favorably under some circumstances. If cows were grouped, a minimum of two groups was generally preferable. If the high producing group did not satisfy the needs of the high producing cows, or the drop in nutrients between groups was substantial, a three group system would appear more favorable.
Ph. D.

Four experiments were conducted on hens of turkey and Japanese quail. In Experiment I, turkey hens were fed diets containing either 0% added fat, 3.5% animal-vegetable fat blend (AV) or 3.5% dry fat product (DF). In Experiment II with turkey hens, 2 holding diets and 4 breeder diets were investigated. The holding diets contained either 0% added fat or 5% of AV. The breeder diets contained 0% added fat of 5% of one of the following: AV, corn oil (CO) or olive oil (OO). In Experiment III with Japanese quail, 3 pre-breeder (PB) and 3 breeder diets (BD) were studied. They contained either 0, 3.5 or 7% added AV. In Experiment IV with Japanese quail, all diets contained 97% of a semi-purified basal diet and 3% of one of the following: corn starch (CS), corn oil (CO), palmitic acid (PA), oleic acid (OA), linoleic acid (LA) or linolenic acid (LN). The fatty acid composition of plasma and yolk lipids of both turkeys and quail was influenced by the fatty acid composition of the diets. Quail fed a CO diet deposited more linoleic acid in the egg than did those on a LA diet. (Abstract shortened by UMI.)

Introduction : Family Poultry (FP) are birds of indigenous breeds living in almost symbiotic relationship with human communities. The chickens are usually free ranging, or have very limited restrains on their access to the village environment. African livestock population statistics for 1995 indicates poultry to be the most numerous species of farm animal (Anonymous, 1996a). More than 80% of poultry are kept in rural areas and contribute substantially to annual egg and meat production (Sonaiya, 1997). Throughout Africa poultry production stems from ancient traditional practices. FP is the most important type of poultry kept on the continent. In general, village producers keep small flocks of between 5 and 20 birds per household (Gueye, 1997a). Women and children play a key role in their management (Kitalyi, 1996). Because of its productivity, FP production has been neglected and is frequently considered by farmers as an insignificant occupation compared with other agricultural activities. Nevertheless, outside urban centers and especially in non-coastal areas, FP provides the population with a vital source of protein and income. In addition, they play an important role within the context of many social and/ or religious ceremonies. Although this type of poultry constitutes an important part of food security for rural households in South Africa, scientists have not explored this area of research for improving or recording this production system. Yet, FP survived for decades without being wiped out, in the interim, their keepers have gathered and stored a wealth of knowledge and experience, ensuring the survival of this genetic resource. The objective of this study was to collect the baseline data on FP production systems, determine their production constraints and achieve data for future use in the intervention strategies.

In order to describe the ontogeny of solid food consumption by pigs and determine its influence on weight gain, before and after an abrupt weaning at 4 weeks of age, individual feed consumption was measured using a technique that combined load cells and video images. Feed consumption varied greatly both between and within litters. Within litters, consumption was positively correlated with birth weight, and with early weight gains. This suggests that greater feed intake was typical of larger and more mature pigs rather than reflecting compensation for poor milk intake by smaller litter-mates. Within-litter differences in weight gain during the two weeks after weaning were positively correlated with birth weight but not correlated with pre-weaning creep feed intake. Creep feed intake appeared to contribute to pre-weaning gains and these were correlated with post-weaning gains; however a more direct affect on post-weaning gain could not be detected.

I consider two types of foraging situations. In the first type, the forager knows the location and quality of no more than one food item or habitat at a time. I call this myopic foraging. In the second situation, the forager may know the location and quality of more than one food item or habitat at a time. I call this periscopic foraging. I develop theoretically both models and the predictions generated by each. Myopic models predict that foragers should have a so-called "bang-bang" control with respect to the choice of food types. Periscopic models predict that foragers will have a continuous control with respect to the choice of food types. I experimentally tested for the presence of each type of control in a field study that employed hummingbirds feeding on artificial resources. As predicted by the theory, the transition of behavior from picky to opportunistic was significantly sharper for the myopic than for the periscopic foragers. Furthermore, theory predicts that there should be some range of relative values of the rich and poor food types over which the myopic foragers are opportunistic, while the periscopic foragers exhibit a partial preference. This prediction was supported by the data. I predicted that the partial preferences of periscopic foragers would result from the hummingbirds exploiting those poor quality feeders which were located nearest to the best foraging path among rich feeders. The data supported this prediction. Periscopic foragers also performed as predicted by becoming more selective on rich feeders as the densities of both rich and poor feeders increased. I developed a model of optimal sampling behavior that hypothesized birds have evolved in an environment of exploitative competition. The model predicted a rule of departure from a resource patch that depended on the presence or absence of nectar in a sampled as well as the expected quality of the nectar. Hummingbirds performed according to the model's predictions.

Thesis (MSc)--Stellenbosch University, 2015.
ENGLISH ABSTRACT: Monensin was approved in the 1970’s as a feed additive to ruminant diets. Since then, many studies on the effects of Monensin were done. Its mode of action includes the improvement of feed conversion by altering rumen fermentation. This alteration results in a change in the rumen microbial population. Some processes that benefit from the manipulation of rumen microbial population are volatile fatty acid production, peptide degradation and amino acid deamination. The use of ionophores as an antibacterial product in animal feeds were banned by the European union ( EU) in 2006 because of chemical residues found in the edible product making it potentially unhealthy for human consumption and it is also socially unacceptable. Thus, alternative sources need to be identified to help improve the rumen microbial population. Such an alternative could be plant based EO. Oregano (Origanum vulgare) is a natural anti-bacterial compound affecting a variety of gram positive and gram negative bacteria. It has been reported to improve the overall health and production of lactating dairy cows by enhancing rumen fermentation. The aim of this study was to determine the effect of an essential oil extracted from oregano on production and rumen fermentation of Jersey cows grazing ryegrass pasture during spring. Effects were determined on milk yield, milk composition, live weight body condition, rumen pH, Ammonia-nitrogen (NH3-N) and volatile fatty acid (VFA) composition, organic material (OM) and neutral detergent fibre (NDF) digestibility of pasture in the rumen. Fifty four early lactation Jersey cows were blocked, according to days in milk (DIM), 4% fat corrected milk (FCM) and lactation number. Cows within blocks were randomly allocated to one of the three treatments. The three treatments were as follows: Control (CON; maize based concentrate with no feed additives), an ionophore treatment, (MON; a maize based concentrate with monensin provided a daily dose at 300 mg per cow), and an essential oil treatment (EO; a maize based concentrate with oregano extract provided at a daily dose of 1.15 g per cow. Cows received 6 kg of concentrate in the milking parlour and were allocated 10 kg dry matter (DM) of ryegrass pasture, divided into two grazing periods after each milking. Before milking, cows were separated into their respective treatment groups for milking and the consumption of their specific concentrate treatments. Milk yield was recorded on a daily basis. Composite milk samples were collected per cow on a bi-weekly basis. Live weight and body condition score (BCS) were determined before and after the study. Six rumen cannulated cows were used in the rumen study. Two cows were randomly allocated to each of the three treatments in a 3 x 3 Latin square design (three treatments and three periods) thus all the cows were subjected to all three treatments over the experimental period. Ruminal pH, volatile fatty acids (VFA) concentration, ruminal ammonia-nitrogen (NH3-N), and in sacco degradability were determined. The daily average milk yield and milk fat content did not differ among treatments (P > 0.05) and were 20.5, 20.3 and 20.4 kg per cow and 4.5, 4.5 and 4.6 % for cows receiving the CON, MON and EO concentrates respectively. Milk protein and milk lactose content increased (P < 0.05) for the two additive treatments in comparison to control and were 3.39b, 3.55a and 3.60a % for milk protein and 4.50b, 4.80a and 4.80a % for milk lactose where cows received the CON, MON and EO treatments, respectively. Ruminal pH values did not differ among treatments, however, the average overall pH over the 24 hour profile was higher for the two additive treatments. There were no differences in total volatile fatty acid concentrations among the three treatments. With regards to individual VFA, propionate was decreased in the MON treatment when compared to the CON treatment. The ruminal ammonia nitrogen concentration did not differ among treatments. There were no differences in DM and NDF degradability (DMd and NDFd) on the 6 h incubation period but monensin increased the DMd at 30 h incubation and both monensin and oregano increased NDFd after 30 h incubation. To conclude the use of monensin and oregano oil extract have shown to be beneficial with regards to increasing the milk protein and milk lactose content as well as the NDFd. The average overall pH from the pH profile resulted in the two additive treatments being higher when compared to the control treatment. This could be beneficial to rumen fermentation and have a positive effect on the microbial population. As monensin and oregano oil extract showed similar results, oregano oil extract can be considered as an alternative natural feed additive to monensin.
AFRIKAANSE OPSOMMING: Monensin is in die 1970's goedgekeur as 'n voerbymiddel in herkouerdiëte. Sedertdien het navorsing met betrekking tot die invloed van monensin vinnig toegeneem. Die werking van monensin sluit die verbetering van voeromsetting in deur die verbetering van rumenfermentasie. Die verandering in rumenfermentasie het ‘n invloed op die rumenmikrobiese bevolking. Sommige prosesse wat voordeel trek uit die manipulasie van die rumenmikrobiese bevolking is onder andere vlugtige vetsuurproduksie, peptiedafbraak en aminosuurdeaminering. Die gebruik van ionofore as 'n antibakteriese produk in veevoere is gedurende 2006 deur die Europese Unie verbied as gevolg van chemiese residue wat in die eetbare produk gevind is. Die residue maak dit moontlik ongesond vir menslike verbruik en dit is ook nie sosiaal aanvaarbaar nie. Alternatiewe produkte wat help om die rumenmikrobiese bevolking te verbeter en manipuleer moet geïdentifiseer word. Een alternatiewe produk is plantgebasseerde essensiële olies. Origanum (Origanum vulgare) is 'n natuurlike anti-bakteriële produk wat 'n verskeidenheid van gram-positiewe en gram-negatiewe bakterieë in die rumen beïnvloed. Daar is gevind dat die algemene gesondheid en produksie van 'n lakterende melkkoeie verbeter deur die verbetering van rumen fermentasie. Die doel van hierdie studie was om die invloed van 'n essensiele olie-ekstrak uit oreganum op die produksie en rumenfermentasie van Jerseykoeie wat raaigras gedurende die lente bewei, te bepaal. Effekte is ondersoek op melkproduksie, melksamestelling, lewende massa, liggaamskondisie, rumen pH, ammoniak stikstof konsentrasie (NH3-N) en vlugtige vetsuursamestelling (VFA) asook ruminale droeë materiaal (DMd)- en vesel-verteerbaarheid (NDFd) van die weiding. Vier en vyftig Jersey koeie in vroeë laktasie is geblok volgens dae in melk (DIM), 4% vet gekorigeerde melk (VGM) en laktasie nommer. Koeie binne blokke is ewekansig aan een van die drie behandelings toegeken. Die drie behandelings was as volg: Kontrole (CON, mielie-gebaseerde konsentraat met geen voer-bymiddel nie), ‘n ionofoor-behandeling (MON; mielie-gebaseerde konsentraat met monensin teen 300 mg / koei per dag), essensiële olie-behandeling (EO; mielie-gebaseerde konsentraat met oreganum ekstrak teen 1.15 g / koei per dag). Koeie het 3 kg konsentraat in die melkstal ontvang met elke melking en 10 kg droeë material (DM) raaigras-weiding is per koei toegeken. Weidingsessies is verdeel in twee periodes, naamlik na elke melking. Voor melking is die koeie geskei om te verseker dat hulle die regte behandeling in die melkstal ontvang. Melkproduksie is daagliks aangeteken. Saamgestelde melk monsters is tweeweekliks per koei versamel. Lewende massa (LW) en liggaamskondisie (BCS) is aan die begin en teen die einde van die studie bepaal. Ses rumen-gekannuleerde koeie is in die rumen studie gebruik. Twee koeie is toegeken aan elk van die drie behandelings in 'n 3 x 3 Latynse vierkant ontwerp (drie behandelings en drie periodes) en al die koeie het gevolglik al drie behandelings gedurende die eksperimentele periode ontvang. Ruminale pH, VFA konsentrasie, ruminale NH3-N, en in sacco degradeerbaarhede; DMd en NDFd is bepaal. Die daaglikse gemiddelde melkproduksie en melkvetinhoud het nie beduidend tussen behandelings verskil nie (P > 0.05) en was 20.5, 20.3 en 20.4 kg/koei per dag en 4.5, 4.5 en 4.6% vir koeie op die drie behandelings (CON, MON, EO), onderskeidelik. Melk proteïen en melk laktose het aansienlik toegeneem (P < 0.05) vir die twee behandelings met die supplemente in vergelyking met die CON behandeling met waardes van 3.4, 3.6 en 3.6% vir melk proteïen en 4.5, 4.8 en 4.8% vir koeie op die CON, MON en EO behandelings, onderskeidelik. Die rumen pH oor 24 uur het nie verkil tussen die drie behandelings nie en die totale VFA konsentrasie het ook nie verskil nie. Die propionaatkonsentrasie het wel afgeneem op die MON behandeling in vergelyking met die CON. Die rumen NH3-N het nie tussen die drie behandelings verskil nie. Die DMd en NDFd verteerbaarhede van die raaigras in die rumen het nie verskil na ‘n 6 h inkubasieperiode nie. Na 30 h inkubasie het monensin ‘n hoër DM verteerbaarheid getoon en in beide die MON en EO-behandelings het die NDF-verteerbaarheid verhoog wanneer dit vergelyk word met die CON. Om saam te vat; die gebruik van monensin en oregano olie ekstrak het getoon dat dit voordelig kan wees met betrekking tot die verhoging van die melk proteïen en melk laktose inhoud, sowel as die NDFd. Die gemiddelde pH van die pH profiel het gelei tot hoër gemiddeldes vir die twee voerbyvoegsel behandelings in vergelyking met die kontrole behandeling. Dit kan voordelig wees om rumen fermentasie te verbeter en dus ‘n positiewe uitwerking te hê op die mikrobiese bevolking. Monensin en oregano olie ekstrak het soortgelyke resultate getoon en daarom kan oregano olie ekstrak beskou word as 'n alternatiewe natuurlike voerbyvoegsel.

Research was conducted in Sri Lanka to evaluate the feasibility of developing cassava (Manihot esculenta Crantz) leaf meal as an animal feed. In feeding trials with broilers, improvements in performance were observed at 10% inclusion of cassava leaf meal (CLM). High levels (20 and 30%) of CLM depressed gain, feed intake and feed per gain. Weights of spleen and liver (% of body weight) linearly increased with increasing levels of CLM. Carcass pigmentation values favored the CLM-based diets. Dietary additives (methionine, sodium thiosulfate or soybean oil plus methionine) improved the growth of broilers fed 20% CLM diet without, however, having any beneficial effect when added to the basal diet. Gain of broilers tended to decrease with increasing dietary levels of cyanide. Feeding trials with growing pigs showed that CLM can be included up to 26.7% level without any effect on performance. Gain and feed per gain were improved at 13.3% CLM level, whereas marked depressions were noted at 40% CLM level. Results of the balance trials indicated that cassava leaf protein is utilized more efficiently by the pigs, although the nutrients in CLM are not as digestible as those in coconut oil meal. The overall results suggest that bulkiness, low energy content, methionine deficiency and presence of anti-nutritional factors, are the major factors limiting the high level use of CLM in non-ruminant diets. Studies on the processing of CLM revealed that simple drying is sufficient to eliminate almost 90% of the initial cyanide level in the fresh cassava leaves. A combination of chopping and 3-day wilting prior to drying proved most effective in lowering the cyanide level of CLM. Field trials conducted with a short-age cassava variety, MU 22, demonstrated that it is possible to increase cassava leaf dry matter yields by defoliating once during the growing season and to produce within 86% of the normal yield of roots. Two defoliations during the growing season depressed the root crop by more than half.
Ph. D.

The main objective of the study was to determine how phase feeding manipulation affects growth performance, feed cost, carcass characteristics and quality of meat from broiler chickens. A total of 180 day old un-sexed broiler chicks (Cobb 500) were separated into 3 dietary treatments of 60 birds per treatment and each treatment was replicated 3 times with 20 birds per replicate. The dietary treatments were as follows: T1 (starter 1-7 days; grower 8-21 days; finisher 22-35 days), T2 (starter 1-14 days; grower 15-21 days, finisher 22-35 days) and T3 (starter 1-14 days; grower 15-28 days; finisher 29-35 days). Feed intake and body weight gains were recorded weekly in kilograms. Average daily gain and feed conversion ratio were computed weekly. At day 35, the chickens were slaughtered and 12 representative breast muscles from each treatment were used for the determination of muscle pH (pH1, pH24 and pH48) and colour coordinates (Lightness – L*, redness – a* and yellowness – b*) in triplicate at 1 hour, 24 hours and 48 hours post-mortem.Feed intake (FI), feed conversion ratio (FCR), average daily gain (ADG) and average body weight at slaughter (ABW) were not significant (P>0.05) amongst the treatments. The most cost efficient feed (which accumulated the cheapest cost feed per kg were) T1 (R11.32) and T3 (R11.32) although there was a slight difference in the gross profit of these treatments T1 (R45.71) and T3 (R44.48). Carcass characteristics were the same (P > 0.05) across the treatments except for the wing, thigh, drumstick and the breast (P < 0.05). T2 had the highest wing weight (166.63±8.60), T1 (113.03±8.60) and the lowest in T3 (74.46±8.60). The thigh weight were greater (P<0.05) in T2 (185.69±4.34); T1 (185.54±4.34) compared to T3 (166.97±4.34) which was lower. Treatments 1 (204.17±6.57), T2 (197±6.57) had heavier (P<0.05) breast weights than T3 (186.06±6.57). Dietary treatments had no significant effect (P > 0.05) on pH of the breast meat. No differences were observed in colour during the 1 hour period after slaughter. At 24 hours after slaughter, the L* values were different (P < 0.05) in T1 and T2 (44.3 ± 0.37; 43.7 ± 0.37), respectively, T1 and T3 were the same. The a*-values were different (P < 0.05) at 48 hours after slaughter for T1 and T3 (4.5 ± 0.27; 3.4 ± 0.27), T2 was the same as T1. It was therefore, concluded that since manipulation of starter phase did not have adverse effects on growth performance, gross profit, slight statistical difference in meat quality attributes and carcass characteristics. Therefore, the manipulation of starter diet has the potential to be used in broiler production.

A study has been carried out to investigate some aspects of the feeding and digestion of the parasitic copepod Lepeophtheirus salmonis (Kreyer, 1837), a serious pathogen of wild and farmed marine salmonids. The alimentary canal consists of a cuticularised foregut and hindgut and a midgut, the latter comprising most of the length of the alimentary canal. It consisted of an anterior diverticulum, and anterior midgut, mid midgut and posterior midgut. All the midgut is lined in the luminal side with a monolayer of digestive epithelium. The latter is supported by a porous basal membrane. Mesenteries suspend the gut in the haemocoel and attach to the basal membrane by means of extensions of their cytoplasm that interlock with the pores of the basal membrane and are intimately associated with the cellular basal membrane of the enterocytes. Four types of cells could be recognised ultrastructurally and were named according a widely accepted nomenclature for the types of digestive epithelial cells found in decapod crustaceans. R-cells were the most abundant type and were believed to be involved in the absorption of nutrients, storage of lipids and probably excretion of waste material. Once the R-cells have finished their useful life, it is proposed that they finally die after passing through a stage, called A-cell stage, comparable to apoptosis or programmed cell death, after which the A-cell is finally sloughed off the epithelium and discarded in the faeces. F-cells constituted the second cell type, in charge probably of the secretion of digestive enzymes. Once this stage is finished, F-cells are believed to transform into the third type of cells, the B-cells, which engage in intracellular digestion of nutrients. At the end of their useful life they are sloughed off the epithelium. The last cell type, the E-cells, are believed to be embryonic cells that differentiate either into R- or F-cells. A revised mode of feeding is proposed, in which the louse scoops up strips of host skin epithelium of relatively constant size and shape, by means of the structures associated with the mouth cone. Analysis of the gut contents and the faecal pellets revealed that the main food item was host skin epithelium. The feeding activity usually reaches the dermal layer, suggested by the common occurrence of host melanin in the gut and in the faecal pellets. Two types of faecal pellets were found. The first type was a cylindrical one which was made of the ingested host's epithelial cells with little signs of having being digested. Cylindrical pellets could be clear or dark depending on the amount of host melanin present in them. The second type of pellet was a tape- or ribbon-like gelatinous pellet produced mainly when the lice were not eating (as during starvation) or sometimes associated to the end of the cylindrical pellets. Pellets were always surrounded by a delicate peritrophic envelope composed of several peritrophic membranes. Blood was believed to be another important food item. Blood feeding was commonly associated with the production of lipids in the R-cells and it is proposed (but not confirmed) that this alternative food item could be associated with some physiological process that requires lipogenesis, like vitellogenesis. A method for manually feeding the lice was devised. Salmon blood and milk were fed in this way. No sign of digestion of these food items was observed suggesting that possibly an endogenous factor different from the presence of food in the gut is necessary to trigger the digestive process. An analysis of type of gut contents, peritrophic membranes and cell type occurrences during a digestive period was carried out. The results suggested that some digestive processes take place preferentially in one or another gut region. Mid and posterior midgut are probably associated with the production of faecal pellets, production of digestive enzymes, intracellular digestion and excretion of waste materials judging by the higher occurrence of peritrophic membranes, B- and A-cells in these regions. Absorption of nutrients probably takes place throughout the midgut. The morphological changes in the topography shown by the midgut epithelium suggest that it is a very active and plastic tissue. The results of this study were discussed and compared with similar studies of other crustaceans, including other parasitic and free living copepod species. Suggestions were made of the implications of the present findings in the search for a control method for this parasite.