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

Assignment (MPhil)--University of Stellenbosch, 2002. / ENGLISH ABSTRACT: The study conducted was aiming on evaluating the influence of different levels of energy and amino acids, mainly lysine and methionine, on production performance of the layer bird. There were three treatments, namely the Control diet, a high energy, lysine and methionine diet (High spec.) and a low energy, lysine and methionine diet (Low spec.). The energy levels were 11.2 MJ/kg, 11.5 MJ/kg and 10.9 MJ/kg respectively. Lysine levels were 0.67%, 0.73% and 0.63% whereas methionine levels were 0.36%, 0.38% and 0.34% respectively. The experimental design was 3 x 4 factorial, which is 3 treatments with 4 replicates each. Results showed no significant difference (P>0.05) between treatments in egg production, egg mass, egg output, bodyweight and mortality. Feed intakes of the High spec. diet were significantly lower (P<0.05) than that of the control diet and the Low spec. diet. / AFRIKAANSE OPSOMMING: Hierdie studiestuk handeloor die evaluering van die invloed wat die verskillende vlakke van die energie en aminosure, veraiiisien en methionine op die produksie van 'n lê hoender het. Daar was gebruik gemaak van drie behandelings, naamlik die kontrole dieet, 'n hoë energie, lisien en methionien dieet (Hoë spesifikasie), en 'n lae energie, lisien en methionien dieet (Lae spesifikasie). Die energievlakke was 11.2 MJ/kg, 11.5 MJ/kg en 10.9 MJ/kg onderskeidelik. Lisienvlakke was 0.67%, 0.73% en 0.63% waarby methionienvlakke was 0.36%, 0.38% and 0.34% onderskeidelik. Die eksperimentele ontwerp was 3 x 4 fakulteitsfunksies: 3 behandelings met 4 replikas elk. Die resultate het geen noemenswaardige verskille (P>0.05) tussen die behandelinge in eierproduksie, eiergewig, eier-uitset, liggaamsgewig en mortaliteite nie. Die voerinnames van die hoë spesifikasie dieet was aansienlik laer (P<0.05) as die van die kontrole en lae spesifikasie dieet.

Thesis (MScAgric)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: The aim of this study was to determine whether a lamb finishing ration that is balanced for essential amino acids (EAA), at a specific level of non-structural carbohydrates (NSC) would yield better feedlot performance when compared to a standard commercial finishing ration. Metionine (Met) and Lysine (Lys) were identified as the first limiting amino acids for growing lambs. These two amino acids, as well as Threonine (Thr), Arginine (Arg), Leucine (Leu), Isoleucine (Ile) and Phenylalanine (Phe) were included in an optimized protein (OP) feedlot ration at optimal levels. This ration was formulated to contain 157 g/kg crude protein (CP) and 477 g/kg NSC, with Met, Lys, Arg and Thr at 2.48, 7.45, 8.51 and 8.12 g/kg on dry matter (DM) basis respectively. The second treatment, FIN, was a standard commercial lamb finishing feed without optimized amino acids and contained similar total protein and NSC to OP of 152 g/kg CP and 468 g/kg NSC but with Met, Lys, Arg and Thr at 2.08, 5.49, 7.47 and 4.80 g/kg on DM basis respectively. A third treatment, a low protein (LP) diet served as a positive control and was formulated on lower specifications (139 g/kg CP, 455 g/kg NSC) and was also not optimized for amino acids. This treatment contained Met, Lys, Arg and Thr at 1.93, 4.99, 6.66 and 4.73 g/kg on DM basis respectively. Lambs grazing kikuyu pasture served as the negative control (CON) group. These lambs also received additional supplementary feed at 500 g/day as a production lick to be comparable to a scenario where lambs are finished on grazing. Forty cross-bred Merino x Döhne-Merino lambs with an average weaning weight of 24.35 ± 0.648 kg were finished in a feedlot for 57 days where after they were slaughtered at an average weight of 41.41 ± 1.259 kg. During the feedlot trial lamb performance was measured by monitoring daily growth rates and feed intake. Also, an in vivo digestibility study was carried out on the OP and FIN lambs. During the slaughter process the rumen was removed which was done to collect a sample of the rumen wall from next to the rumino-reticular fold. These rumen samples were mounted onto slides so that the development of the rumen could be examined. The M. longissimus dorsi from both sides of the carcass between the 2nd and 3rd last thoracic vertebra and the 4th and 5th lumbar vertebra were removed. There was no significant difference (P > 0.05) between any of the concentrate feed treatments with regards to the average daily gain (ADG), feed conversion ratio (FCR) or dressing percentage (DP). The CON lambs, as expected, had lower growth rates (P < 0.05) than the concentrate fed lamb and thus showed significant differences (P < 0.05) in terms of ADG. The DP of 45.96 % ± 0.711 for the CON lambs differed significantly (P < 0.05) from the OP (51.44 % ± 0.358), FIN (52.72 % ± 0.653) and LP (51.74 % ± 0.611) treatments. As expected the concentrate feeds were much more effective in maintaining higher growth rates when compared to the CON lambs while the optimizing of EAA in the OP diet did not lead to improved feedlot performance as the FIN and LP treatments were able to achieve similar (P > 0.05) growth rates. Within the feedlot treatments there was no significant difference (P > 0.05) with regard to the papillae length and rumen wall thickness. There was however a numerical increase in the papillae length as the NSC levels in the feed increased. The CON lambs differed from the OP lambs (P < 0.05) in terms of papillae length. This illustrated the importance of having increased levels of NSC in a feedlot diet as it is this fraction that is responsible for the initialisation and maintenance of rumen morphological development. The in vivo digestibility study therefore confirmed that the commercial finishing feed was just as effective as the optimized feed in terms of nitrogen retention as well as in maintaining suitable energy balance. Although the in vivo digestibility for Met and Lys in the OP feed was higher (P < 0.05) than the FIN feed, this did not lead to improved feedlot performance of the OP lambs. The increased digestibility of these amino acids is due to the fact that the OP diet was higher in levels of bypass amino acids than the FIN feed. The in vitro true digestibility (IVTD) of the OP feed was higher (P < 0.05) than that of the FIN feed. / AFRIKAANSE OPSOMMING: Die doel van hierdie studie was om te bepaal of ‘n lamafrond rantsoen wat gebalanseerd is vir beperkende essiensiële aminosure (EAA) teen ‘n spesifieke vlak van nie-strukturele koolhidrate (NSK) beter voerkraal prestasie teweeg sou bring wanneer gemeet word teen ‘n standaard kommersiële afrond rantsoen. Metionien (Met) en Lisien (Lis) is geïdentifiseer as die eerste beperkende aminosure vir groeiende lammers. Hierdie twee aminosure, asook Treonien (Tre), Leusien (Leu), Isoleusien (Ile) en Fenielalanien (Fen) is teen optimale vlakke ingesluit in ‘n geoptimeerde voerkraal rantsoen, OP. Hierdie rantsoen is geformuleer om 157 g/kg RP en 477 g/kg NSK te bevat asook Met, Lis, Arg en Tre teen 2.48, 7.45, 8.51 en 8.12 g/kg onderskeidelik. Die tweede behandeling, FIN, was ‘n kommersiële lamafrond voer waarin die aminosure nie geoptimeer is nie en het soortgelyke vlakke van proteïene en NSK bevat teen 152 g/kg RP en 468 g/kg NSK met Met, Lis, Arg en Tre teen 2.08, 5.49, 7.47, 4.80 g/kg onderskeidelik. ‘n Derde voer, LP, het gedien as ‘n positiewe kontrole en was ‘n lae proteïen voer met laer spesifikasies (139 g/kg RP, 455 g/kg NSK) waarin die aminosure ook nie geoptimeer is nie. Die LP voer het Met, Lis, Arg en Tre bevat teen 1.93, 4.99, 6.66 en 4.73 g/kg onderskeidelik. Die negatiewe kontrole behandeling, CON, is verteenwoordig deur lammers wat op kikuyu gewei het terwyl addisionele supplementêre voeding teen 500g/lam/dag voorsien is. Hierdie supplementêre voeding het gedien as ‘n produksie lek om sodoende vergelykbaar te wees met scenario waar lammers op weiding afgerond word. Veertig kruisgeteelde Merino x Döhne-Merino lammers met ‘n gemiddelde gewig van 24.35 ± 0.648 kg is vir 57 dae in ‘n voerkraal afgerond waarna hulle, teen ‘n gemiddelde gewig van 41.41 ± 1.259 kg, geslag is. Tydens die voerkraal proef is prestasie gemonitor deur die meet van daaglikse groei en voerinname. Hiertydens is daar ook ‘n in vivo verteringsproef op die OP en FIN lammers gedoen. Tydens die slagproses is die rumen verwyder waarna ‘n monster van die rumenwand langs die rumino retikulêre vou geneem is. Hierdie rumenmonsters is op skyfies geplaas sodat die ontwikkeling van die rumen ondersoek kan word. Die M. longissimus dorsi was aan beide kante van die karkas tussen die 2de en 3de laaste torakale werwels en die 4de en 5de lumbale werwels verwyder. Daar was geen betekenisvolle verskille (P > 0.05) tussen enige van die konsentraat behandelings ten opsigte van gemiddelde daaglikse toename (GDT), voeromset verhouding (VOV) of uitslag persentasie nie. Die CON lammers het egter, soos verwag, beduidend (P < 0.05) stadiger gegroei en het dus verskille getoon ten opsigte van GDT. Die uitslag persentasie van 45.96 % ± 0.711 vir die CON lammers het ook betekenisvol verskil (P < 0.05) van die OP (51.44 % ± 0.358), FIN (52.72 % ± 0.653) en LP (51.74 % ± 0.611) behandelings. Binne die voerkraal behandelings was daar geen betekenisvolle verskille (P > 0.05) ten opsigte van die papillae lengte en rumenwand dikte nie, alhoewel daar ‘n numeriese toename in papillae lengte was soos die NSK vlakke in die voer gestyg het. Die CON lammers het wel van die OP lammers verskil (P < 0.05) ten opsigte van papillae lengte. Hierdie bevinding het bevestig hoe belangrik NSK is in die inisiasie en instandhouding van die morfologiese ontwikkeling van die rumen. Die in vivo verterings studie het daarop gedui dat die kommersiële afrond voer net so effektief soos die geoptimeerde voer was in terme van stikstof retensie asook die handhawing van ‘n geskikte energie balans. Alhoewel die in vivo verteerbaarheid van Met en Lis in die OP hoër was (P < 0.05) as in die FIN voer, het hierdie verskille nie gelei tot beter groei in die OP lammers nie. Hierdie verskil in verteerbaarheid is toegeskryf aan die feit dat die aminosure in die OP voer meer rumen-beskermd was as dié in die FIN voer. Die in vitro verteringstudie het daarop gedui dat die OP voer beduidend beter (P < 0.05) verteer is as die FIN voer.

Many of the anabolic effects of growth hormone (GH) are indirect, occurring through GH-stimulated production of insulin-like growth factor-I (IGF-I) by the liver. As well as being GH regulated, plasma IGF-I concentrations have been demonstrated to be dependent upon protein nutrition, with low protein diets being associated with reduced plasma IGF-I concentrations. This effect cannot be reversed by GH, suggesting that liver sensitivity to GH is impaired. To investigate the mechanisms through which protein supply affects GH sensitivity, primary cultures of ovine hepatocytes were grown in defined media. In a first experiment the media contained various fractions (0.2, 1.0, 5.0) of portal vein amino acid concentrations in fed sheep. In the second 24h incubation period, unstimulated IGF-I secretion was highly sensitive the concentration of amino acids in the media, with significantly greater release of basal IGF-I in 5x compared to either 1x (P<0.05) or 0.2x amino acid containing media. In a second series of experiments the effects of specific amino acid depletions was examined. Methionine depletion of 0.2x portal amino acid concentrations ablated the GH response second 24h of culture without affecting basal IGF-I release. By comparison ³H-leucine incorporation into secreted protein, following 20 hours of culture in defined media was significantly reduced in 0.2x aa (P<0.01) and 1.0x aa (P<0.05) media compared with 5.0x aa media, however secretory protein synthesis was unaffected by methionine depletion to 0.2x portal concentrations. The results suggest that amino acid availability regulates both basal and GH stimulated IGF-I release in ovine hepatocytes. Furthermore reducing methionine concentrations in the culture media to 0.2x portal concentrations diminishes GH response without compromising protein secretion.

Limited published data exists on the Australian duck industry, particularly in relation to the nutritional requirements of the commercial duck (Anas Platyrhynchos). A series of seven experiments was designed to determine whether current nutritional recommendations for energy, lysine, methionine, threonine and tryptophan were sufficient to optimise growth, feed efficiency, and carcass characteristics of the duck. The ability of the duck to perform diet self selection was then examined for its potential use in the Australian industry. The outcome of the diet self selection experiments showed that ducks sometimes self select diets when offered choices from four diets differing in nutrient density. A key outcome of this research was the development of a revised set of nutrient specifications designed to maximise the performance of the Australian commercially grown duck. These proposed specifications could be economically beneficial to the expanding Australian duck industry / Doctor of Philosophy (PhD)

Bibliography: leaves 226-261. Investigates nitrogen utilization in some species of rumen bacteria with the object of understanding the role of ammonia versus exogenous amino acids in relation to microbial growth.

Bibliography: leaves 151-166. This thesis describes the development of two novel and complementary analytical approaches for assaying cyanoalanine non-protein amino acids. These assays are used to determine the distribution of these compounds both within and between plants and to identify accessions of common vetch which contain low levels of the cyanoalanine non-protein amino acids in germplasm collections. These analytical tools are used to correlate toxicity observed in animal feeding experiments with the cyanoalanine content. This thesis covers also the first report of the use of diffuse reflectance using dispersive infrared spectrometry for the "in situ" quantification of specific organic components from plant tissue as well as the first use of micellar electrokinetic chromatography for the quantitative analysis of 9-fluorenylmethyl chloroformate (FMOC) derivatised and non-derivatised components of extracts from plant material.

Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 112-120). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 112-120). Also available on the Internet.

Title from PDF of title page (University of Missouri--Columbia, viewed on Feb 18, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Thesis advisor: Dr. Jeffre Firman. Includes bibliographical references.