Rozprawy doktorskie na temat „Feeding and feeds”

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.

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.

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.

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

Clinoptilolite is a zeolite and an aluminosilicate that can be fed to swine in order to reduce nutrients being excreted because of their molecular sieving properties, high cation exchange capacities, and a high affinity for the ammonium ion (NH4+). Preliminary research has been carried out on utilizing zeolite's unique characteristics for dietary supplementation for livestock, however much of this research is limited and is still in its infancy.
The results from this study show that the zeolite with a particle size distribution either >250 mum or mixed (50% particles greater and smaller than 250 mum) adsorbed the most NH4+. Macro mineral and heavy metal release was similar among all particle size distributions tested, but varied between sources of zeolite. Handling properties of zeolite were not affected by moisture content or particle size. The feed trial indicated that zeolite supplementation, combined with a low crude protein and energy diet and at an inclusion level of 4%, showed potential as a feed additive in swine diets for the purposes of nutrient reduction. Nevertheless, zeolite seemed to have a greater impact on energy ingestion, as compared to crude protein. Even at 6% zeolite inclusion in the feed, hog muscle, kidney and liver tissues showed no significant increase in heavy metal contents, as compared to those fed any zeolite.

The rapid growth of Canadian pork industry has been challenged by its negative impact on the environment. To find an economical and promising solution to the environmental problems, 4% zeolite (90%+ clinoptilolite) were supplemented to a regular (100% crude protein (CP) and energy) or low CP and energy (90% CP and 90% energy or 90% CP and 85% energy) grower pig diets. Twenty male and twenty-four female grower pigs were used in two feeding experiments respectively, followed by a metabolic test with three batches of animals repeated to determine the metabolic effects of zeolite supplementation. Pig performance (body weight gain, daily feed intake and feed conversion ratio), and metabolic parameters (manure mass, feed intake, protein and energy conversion, as well as dry feed and organic matter retention) were evaluated. Zeolite supplementation at 4% to a regular diet for grower pigs had a positive but not significant (P > 0.05) effect on all pig performance and metabolic parameters, compared to the regular diet without zeolite. Among 4 rations, pigs on a regular diet with 4% zeolite performed consistently best throughout the entire trail, with decreased average daily consumption and reduced amount of feces, increased feed and organic matter retention in the gastrointestinal tract, improved feed as well as protein and energy conversion, and enhanced body weight gain. Moreover, zeolite supplementation at 4%, with 90% CP and 90% energy in grower pig diets, improved feed and protein and energy conversion rate, and increased body weight gain, when compared to those of pigs fed a regular diet without zeolite. However, a diet of 90% of CP and 85% of energy with 4% zeolite significantly (P < 0.05) increased feed consumption and the amount of feces produced, and decreased feed and organic matter retention in the gastrointestinal tract, thus reducing feed conversion rate. Therefore, 4% zeolite supplementation to the regular or low CP and energy (90% C
Key words. Clinoptilolite, Pig, Pig Performance, Metabolic Parameter.

A replicated 3 x 3 latin square design (3 periods and 6 rumen fistulated steers) was utilized to investigate the effect of dietary concentrate levels (30, 60 and 90%) on the in situ disappearance of dry matter (ISDMD) and neutral detergent fiber (NDF) and kinetics of fiber digestion of alfalfa hay, wheat straw and steam processed and flaked milo (SPFM). Concentrate levels of 30 and 60% did not affect (P > .05) ISDMD or NDF disappearance from any of the substrates. However, ISDMD and NDF disappearance of all substrates were depressed (P < .05) by the 90% concentrate diet. The degradation of the potentially digestible fiber in these substrates followed first order kinetics at all concentrate levels. Fiber digestion kinetics were not affected (P > .05) by dietary concentrate levels of 30 or 60%. Incubation of substrates in animals receiving the 90% concentrate diet resulted in lower potential extent of digestion (P > .05) and decreased rate of degradation (P > .05) for all substrates. However, digestion was not complete even after incubations of 168-h, and thus, it is possible that the potential extent of digestion was underestimated. For all substrates lag time of digestion appeared to increase in the 90% concentrate diet. However, influx of NDF-like material into the bag during incubation makes the validity of the lag times obtained in situ questionable. Ruminal pH was depressed in animals consuming the 90% concentrate diet and could be at least one of the factors responsible for the decreased (P > .05) fiber digestibility in this diet. Mean ruminal pH of 6.5 (30 and 60% concentrate diets) did not depress (P > .05) fiber digestibility while a mean pH of 6.2 resulted in a lower (P > .05) fiber digestibility in the rumen.

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).

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.

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 effect of treatment with 3% aqueous ammonia and 5.3% urea plus jackbean meal on the nutritive value of wheat straw was investigated. The moisture content of the straw was raised to 40% by addition of water. Crude protein and in vitro dry matter digestibility were highest for the bottom layers, which had the highest moisture. The mean temperature during the first 4 wk post treatment was 11.2 C. Four diets were fed to sheep: untreated straw 1) alone or 2) with 20 g/d urea at feeding time 3) ammonia-treated straw, and 4) urea-treated straw. All diets contained 80 g of liquid molasses, 10 g of NaCl and 6 g of Na 2 S04, and were calculated to be isonitrogenous except the control diet (untreated straw without urea supplementation). Straw was chopped prior to feeding. Crude protein content in wheat straw was tripled by ammonia and urea treatment. Dry matter digestibility in vivo and in vitro was enhanced by ammonia and urea treatment, and the effect was higher for ammonia treatment. Digestibilities of cell wall constituents were higher (P<.05) for ammonia treated straw, compared to urea-treated straw. Urinary N excretion was considerably lower (P<.01) and N retention was higher (P<.01) for lambs fed treated straws, compared to those fed urea at feeding time. Ruminal NH3-N and blood urea concentrations were higher (P<.01) for the lambs fed urea at feeding time, compared to lambs fed the others diets.
M.S.

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.

This study was designed to provide information on some of the factors affecting voluntary consumption and digestibility of forages by sheep. A wet sieving procedure was used to determine particle size distribution in the reticulo-rumen, omasum and abomasum of sheep fed 100 % prebloom alfalfa or 100 % second-cut Altai wild ryegrass hays or mixtures of these with tall wheatgrass or Altai wild ryegrass straws. The study also compared second-cut Altai wild ryegrass and prebloom alfalfa as components in an all forage diet for sheep. Each diet was fed ad libitum to eight Romanov x Western whiteface wether lambs weighing 22 to 25 kg during the intake and digestibility trials. For the determination of particle size distribution, the animals were slaughtered at 12, 24, 36, and 48 hours after feed removal and the contents of the reticulo-rumen, omasum and abomasum sampled. Five different methods of describing digesta particle size distribution were compared as to their ability to predict voluntary intake and digestibility of the forages by sheep. The best method for expressing particle size distribution in the reticulo-rumen in terms of ability to predict dry matter digestibility (DMD) was the proportion of soluble dry matter in total dry matter (PSDM). A significant (P< 0.05) correlation (r = 0.84) between PSDM and dry matter digestibility, 12 hours after feed removal was obtained. PSDM in omasal digesta 24 hours after feed removal was also highly correlated with DMD and energy digestibility (r = 0.97, 0.91, respectively). Very high correlations were obtained between PSDM in abomasal digesta 24 hours after feed removal and digestibility of cellulose, NDF and ADF (r = 0.99, 0.97 and 0.97 respectively). The proportion of particles less than 1mm to the total particles (PIP) in the reticulo-rumen gave the most consistent correlations with intake of dry matter and energy. Voluntary intake of dry matter by the animals on the alfalfa-based diets were significantly higher (P< 0.05) than those on the second-cut Altai wild ryegrass-based diets. However, the apparent digestibility coefficients of the proximate fractions in the Altai wild ryegrass diets were significantly higher (P< 0.05) than those of diets containing alfalfa. Daily intake of digestible energy by animals on 100 % alfalfa was not significantly different from that of animals on 100 % second-cut Altai wild ryegrass. The difference between their respective combinations with tall wheatgrass and Altai wild ryegrass straws were also not significant. It was concluded that PIP and PSDM are indeces based on biologically significant fractions and may therefore have greater relevance than purely mathematical or statistical descriptions of particle size distribution in digesta. In this regard, the relationship between PSDM and digestibility and, PIP and intake are consistent with published theory and can be used in mathematical models to examine control processes in feed intake, rate of passage and digestion. The study also indicated that second-cut Altai wild ryegrass harvested at the prebloom stage can be used as a substitute for alfalfa in an all-forage diet for winter feeding of sheep.
Land and Food Systems, Faculty of
Graduate

Carbohydrates have variable digestibilities and metabolizable energy values in carnivorous fish. Simple sugars are generally more digestible than complex polysaccharides, and low levels of dietary carbohydrate may contribute more metabolizable energy than high levels. Two experiments were conducted to study the effects of dietary level and processing treatment of wheat starch on the digestibility of diets fed to sablefish (Anoplopoma fimbria), in different regions of the digestive tract. Moreover, an experiment was undertaken to determine if the dietary concentration of an indigestible external marker (chromic oxide) influenced its motility, relative to other ingredients in the ingesta, as it passed through the digestive tract. Lastly, a growth experiment was undertaken to compare the performance of sablefish fed formulated diets containing one of two levels of carbohydrate to that of fish fed a natural fish diet. The gastric evacuation of a formulated and a natural diet were also investigated. Apparent digestibility values for the nutrients in a formulated diet (containing 44.4% cooked wheat and 0.1% chromic oxide) fed to sablefish were noted to increase progressively from the anterior to the posterior regions of the intestinal tract. Within each region of the gut, the apparent digestibility values for most nutrients declined over three sample periods. Carbohydrate (nitrogen-free extract) digestibility down to the distal section of the intestine ranged from 51.0 to 82.8%. An experiment designed to assess the effect of carbohydrate treatment on the digestibility of four isonitrogenous, isocaloric diets met with partial failure. It was determined that the 1.0% chromic oxide marker flowed at a differential rate to the rest of the ingesta in the digestive tract, which violated the criteria for an effective marker. Consequently, diet digestibility was not determined in this experiment. Hepatic glycogen levels in fish receiving the dietary treatments were compared, and these values were used to estimate the relative availability (digestibility) of carbohydrate from the respective diets. According to this index, the sequence for digestibility was as follows: pregelatinized starch > cooked wheat > pregelatinized starch/cooked wheat > unprocessed wheat. Differential movement of chromic oxide relative to other ingesta was observed in sablefish fed on alternate days regardless of the dietary concentration of the indigestible marker (0.1 or 1.0%). It was surmised that the feeding protocol established the circumstances from which marker 'streaming' was observed in the results. Differential transport of Cr₂O₃ through the gut by ingested seawater was suggested as a possible mechanism for the phenomenon. Sablefish fed a natural fish diet had the highest growth rates, condition factors, liver lipid levels and the lowest feed conversion ratios and liver glycogen levels. Sablefish fed a diet containing 22.2% cooked wheat had a higher growth rate, condition factor, and a lower food conversion ratio, than those fed a diet containing 44.4% cooked wheat. Ingestion of the 44.4% cooked wheat diet resulted in the highest values for liver glycogen and hepatosomatic index. It was concluded that sablefish have a limited ability to metabolically utilize digestible carbohydrate and that most of the dietary non-protein energy should originate from high quality lipid for maximum protein sparing.
Science, Faculty of
Resources, Environment and Sustainability (IRES), Institute for
Graduate

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).

The study presented in this thesis is origina] and was compieted by the author. a post—graduate student in the Department of Animal Husbandry. University of Sydney. New South Wales. Austra1ia. under the supervision of Dr. D.M. Waiker.

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.

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

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

Food waste accounts for about 1/3 of the municipal waste generated in Hong Kong. Using food waste as major ingredients to produce fish feed pellets could ease part of the disposal pressure on the existing landfill sites. The present study focused on the use of food wastes and feed supplements (prebiotic fibres and Chinese herbs) for rearing freshwater fish (grass carp, bighead, mud carp and Nile tilapia) in Hong Kong. Two isonitrogenous formulations, Food Waste Diet A (FWA), consisted of 53% cereal, 10% fruit and vegetables, 8% bone meal, 4% other food waste, 10% fishmeal, 15% corn meal and Food Waste Diet B (FWB), consisted of 25% meat, 28% cereal, 10% fruit and vegetables, 8% bone meal, 4% other food waste, 10% fishmeal, 15% corn meal were manufactured by Kowloon Biotechnology Ltd, were used as feeds for rearing grass carp, bighead, mud carp and Nile tilapia. The essential amino acid profiles and proximate compositions (crude protein, crude lipid and total phosphorous) of the two food waste based feed pellets were compared with other common feed items, including Napier grass, rice bran, breads, noodles, soybean dreg (remains of soybean after juicing for soybean milk) and the commercial feed pellets (Jiefeng® 613). Jiefeng® 613, FWA and FWB possessed 5.83%, 5.76% 5.79% (% protein) of lysine, which could satisfy the dietary requirements of both grass carp and Nile tilapia. Results indicated all the fish feed pellets possessed sufficient essential amino acids and suitable proximate compositions (crude lipid, crude protein, crude fibre and non-fibrous carbohydrate) for both grass carp and Nile tilapia. A field trial was conducted using the three feed pellets (Jiefeng® 613, FWA and FWB) to study their effects on fish growth (grass carp, bighead and mud carp) as well as water quality. FWA that possessing a higher P content (2770 μg/g feed, while control= 967 μg/g feed and FWB= 1942 μg/g feed) favoured the growth of plankton and led to better growth of bighead carp (in terms of length gain, wet weight gain and productivity), while grass carp fed with FWB showed significant better growth (in terms of length gain, wet weight gain, productivity, feed conversion ratio, specific growth rate and protein efficiency ratio), probably due to the relatively lower amount of carbohydrate (24.2%) and CHO:L ratio (1.83) than Control and FWA. Mud carp grew equally well in ponds fed with the three diets. FWB was subsequentially selected for further feeding experiments. A laboratory feeding trial was conducted to study the effects of feeding grass carp and Nile tilapia with FWB on their growth performance in terms of relative weight gain (RWG), feed conversion ratio (FCR), specific growth rate (SGR) and protein efficiency ratio (PER), and protein digestibility. Both fish fed with FWB showed similar growth performances to groups fed with control diet (Jiefeng® 613), while grass carp showed impaired protein digestibility when compared to group fed with control diet. FWB supplemented with 0.3% of vitamin-mineral premix (VMP) significantly improved the growth performance of both fish species and protein digestibility for grass carp. Results suggested that FWB incorporation with VMP would be necessary as it significantly enhanced growth of the fish. Four dietary supplements (inulin, mannan-oligosacharride, huangqi and goji, at the rates of 0.2% or 2%, w/w) were incorporated into FWB for further enhancing fish growth as well as non-specific immunity of grass carp and Nile tilapia. Grass carp fed with 0.2% and 2% inulin, 2% MOS and 0.2% goji, and Nile tilapia fed with 0.2% goji had significantly enhanced growth (RWG, FCR, SGR and PER). Both prebiotic fibres and Chinese herbs boosted the tested non-specific immune parameters (total serum immunoglobin, serum bactericidal activity and anti-protease activity) of both species. Among all the dietary supplements, 0.2% goji appeared to be the best supplement for both grass carp and Nile tilapia as it significantly enhanced the growth among all experimental diets. Grass carp and Nile tilapia fed with 0.2% showed about 10% and 30% higher RWG, 10% and 30% lower FCR value, respectively, than groups fed with other experimental diets. Moreover, all the tested non-specific immune parameters (total serum immunoglobin, serum bactericidal activity and anti-protease activity) were significantly enhanced when compared with the groups fed with control diets (Control and FWB without supplementation) . The present study demonstrated the feasibilities of using food wastes incorporated with feed supplements (prebiotic fibres and Chinese herbs) to enhance fish growth and immunity, for the sustainable development of Hong Kong inland aquaculture.

Effects of tallow supplementation on dietary nutrient and minimal amino acid utilization in the laying hen were studied in two experiments. In the first experiment diets contained six levels of animal tallow ranging from 0 to 10%. Percent egg production and egg mass were not significantly affected by tallow. Body weight was significantly increased by 2% tallow was maximum at 6%. Addition of up to 6% fat improved feed conversion without adversely affecting other production characteristics. Metabolizable energy (ME) intake increased from 305.1 to 322.4 kcal/hen/d over the range of 0 to 6% tallow with no further improvement at higher tallow levels. Maximum net energetic efficiency was obtained with 2 and 4% tallow. Ability to digest tallow declined significantly with hen age. Higher tallow ME values were obtained from calorimetry data than from digestibility measurements due to beneficial effects of tallow on digestibilities of fat and protein in the basal diet. No improvement in starch retention was observed with tallow supplementation. In the second experiment, diets containing four levels of protein (15.0, 13.6, 15.0 + methionine and 17.0%) without and with 3% tallow were fed to hens housed in an open cage house or an insulated, evaporatively cooled house. Egg production and egg mass were significantly higher in the insulated house. This study indicates that reducing total protein below the National Research Council (NRC, 1984) recommended level significantly reduced egg production by birds housed in an open house. Supplemental methionine to provide .60% TSAA was required for maximum egg production. Egg production was significantly improved with the low protein diet when 3% tallow was added; however, egg production rate supported by this combination was significantly below that obtained with the 17% protein diet either with or without added tallow. For birds housed in the insulated, evaporatively cooled house the diet based on the NRC amino acid recommendations appeared to be optimal for performance, even with a lower protein level. No additional benefits were obtained in egg production with 3% tallow in any of the diets under these housing conditions.

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

The most common disease causing elements in feed is of microbial nature. Therefore it is of great importance for horse owners to be familiar with the fundamental requirements for microbial growth in feeds and the problems that can originate in case of insufficient handling. However, horse owners are not organized in a way that makes it easy to reach them with information as a target group. Additionally, most horse owners only have one horse and limited possibilities for education in feed safety. Thus, there is need for an easy accessed education material that is explicitly directed towards horse owners. The fundamental content of such an education material was composed in this project. Focus was on the importance of good microbial quality in horse feed and the material was structured into three chapters; FEED SAFETY, MICROORGANISMS IN FEEDS and CONSERVATION, STORING AND FEEDING. The aim was to publish the material as part of a larger web based education package on the web page, http://www.sva.se of the Swedish National Veterinary Institute. The basic structure for such a web education was also composed in this project.

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.

Linseed meal (LSM) was fed to ovariectomized ewes exposed to estradiol 17-? (E2) implants over time, and LSM was supplemented to beef cows during late gestation and early lactation to evaluate the estrogenic potential of the phytoestrogen secoisolariciresinol diglycoside (SDG) found in LSM. Forty-eight ovariectomized ewes were fed a diet containing 12.5% LSM for 0, 1, 7, or 14 d and implanted with estradiol-17? (E2) for 0, 6, or 24 h before tissue collection. Uterine cellular proliferation, vascularity, and the expression of the angiogenic factors and their receptors were recorded. There was an interaction of LSM and E2 on uterine mass (P = 0.05). At 24 h of E2 exposure, proliferation was reduced (P < 0.001) when ewes were fed for 14 d compared to being fed 0 or 1 days. There was a LSM x E2 interaction (P ? 0.03) on VEGF receptor-2 (KDR) and hasicfihrohlast growth factor receptor (FGFR2) decreasing by 24 h E2 exposure. Exposure of LSM and E2 may impact the estrogenic response of sensitive tissue. Two studies were conducted to examine the effects of supplementing beef cows with LSM during late gestation or early lactation on calf growth and development. In Experiment 1, multiparous cows received either LSM or a control (CON) supplement (approximately 10% diet dry matter) for the last 60 d of gestation. Offspring weights, ADG, heifer age at puberty, conception percentage and steer carcass characteristics were recorded. In Experiment 2, multiparous cows received LSM or CON supplements (approximately 10% diet dry matter) during the first 60 d of lactation, and only heifer calf development performance was observed and recorded. Heifer calf weight, average daily gain, and attainment of puberty were assessed. For both experiments, birth weight, weaning weight and ADG were not affected (P > 0.31) by LSM supplementation. While final body weights were heavier (P = 0.04) for steer calves in Experiment 1, there was no effect (P = 0.09) of supplementation on carcass characteristics. In Experiment 1 and 2, attainment of puberty in heifer calves was not influenced (P > 0.58) by supplement type. Linseed meal supplementation during late gestation or early lactation does not appear to have a negative impact on calf growth, onset of puberty in heifer calves, or steer carcass quality, implicating that it may make a good supplement choice in cattle.

Equations to predict daily dry matter intake (DMI) of individual animals were developed with 118 Holstein heifers fed totally mixed rations (TMR). Animals grouped according to body weight (136, 227, 317 kg) were fed TMR (corn silage, ground hay, high moisture corn, soybean meal) once daily for 28 days. Rations were balanced to mean body weight according to National Research Council (NRC) recommendations for protein, vitamins and minerals, and to 85, 95, 105, and 115% of recommendation for energy. Independent variables were body weight (BWT, kg/day) daily body weight gain (GAIN, kg), environmental temperature (AMBT, °C), ration acid detergent fiber (ADF, percent of dry matter), neutral detergent fiber (NDF, percent of dry matter), net energy for maintenance and gain (NEM, NEG, megacalories), total digestible nutrients (TDN, percent of dry matter), and bulk density (BULK, g/ml as fed). Squared terms, appropriate interaction terms, and metabolic body weight (MBWT, kg^.75) were included in the model. Stepwise regression was utilized to generate two models, simplified and expanded. Simplified model was: DMI (kg/day) = -29.86 + (-.54E-05 * BWT²) + (.157 * MBWT) + (2.090 * GAIN) + (-.118 * GAIN²) + (.730 * TDN) + (-.005 * TDN²) + (-.001 * BWT * GAIN) + (-.019 * TDN * GAIN); n = 4797, r² = .59, s_y.x = 1.18. Expanded model was: DMI (kg/ day) = -1906.91 + (-0.04 * BWT) + (0.37 * MBWT) + (32.36 * ADF) + (2305.51 * NEM) + (-664.06 * NEG) + (-0.08 * AMBT) + (-0.13 * ADFSQ) + (-637.68 * NEMSQ) + (42.31 * NEGSQ) + (-5.35 * BULKSQ) + (0.001 * AMBTSQ) + (-1.56E-04 * BWT * ADF) + (8.873E-05 * BWT * AMBT) + (246.30 * NEM * NEG) + (-21.30 * NEM * ADF) + (7.83 * NEG * ADF) + (0.04 * NEG * AMBT) + (0.01 * GAIN * ADF) + (-0.01 * GAIN * AMBT); n = 4429, r² = .65, s_y.x = 1.09. Predicted intakes by simplified equation agree with those of NRC at TDN recommended by NRC and .7 kg/day. Computerized ration formulation systems were developed using simplified model. Expanded model requires further refinement prior to incorporation into a ration formulation system.
Ph. D.

Includes bibliographical references (leaves 290-309) Investigates aspects of the intake and utilization of barley grain and grain legume supplements by sheep fed low quality pasture hay and when grazing mature summer pastures.