One hundred eight male and 206 female breeder turkeys were fed isocaloric corn-soy rations containing 8, 10 or 12, and 10, 12 or 14'% crude protein, respectively, to which 0.0, 0.1, 0.2, or 0.3% DL-methionine was added in a factorial arrangement of treatments,. With the exception of percentage hen-day egg production and egg size, dietary treatment had no significant effect on the reproduction of females or on the growth of the progeny. Egg production was higher among females fed 12 and 14% protein than among those fed 10% protein. Those fed 14% protein laid the heaviest eggs. Female serum albumin concentrations and the concentrations of blood threonine and lysine significantly increased while concentrations of blood glycine decreased with increased levels of dietary protein. Optimum semen volume and spermatozoa concentration were obtained for males fed 10% protein. For females, the significant response obtained in egg production to increased protein levels and the failure to obtain this response with increased total sulfur amino acid (TSAA) levels as a percentage of total protein, indicates that other amino acids may have been limiting. Based on these results, it appears that for optimum reproduction of Medium White breeder turkeys, a daily intake of at least 22.7 g protein and 696 mg TSAA are necessary for females, and 25.0 g protein and 1,175 mg TSAA are necessary for males. / Master of Science

Mammary cells from lactating rats and dairy cows were cultured in Eagle's minimal essential medium (MEM) with added amino acids. Changes in free intracellular amino acid pools and milk protein synthesis in response to amino acid additions to the medium were measured. Increases in free intracellular amino acid pools are associated with increased protein synthesis and the rate of their change in response to extracellular amino acids would partially reflect the cell's amino acid requirement. The intracellular pools from medium amino acids (except methionine, tryptophan and glutamine) increased with extracellular amino acids but at their own characteristic rate. The ratio of medium amino acids to nonmedium amino acids inside the mammary cell increased with the concentration of amino acids in the medium. Methionine and tryptophan did not have measurable pools in the rat mammary cell and only very small pools in the bovine mammary cell which did not increase with extracellular amino acids. Culturing rat mammary cells with labeled methionine showed only 42% of the intracellular radioactivity was still associated with labeled methionine indicating significant conversion of this amino acid after it entered the cell. A small linear increase in intracellular cystine was observed with elevated cystine in the medium. The responses in cystine, tryptophan and methionine intracellular pools to extracellular amino acids suggest the concentration of these amino acids in the medium are insufficient to meet the bovine mammary cells requirement. Increasing the concentration of amino acids in MEM 1-, 3-, 5- and 7 fold significantly (P < .05) increased β-casein and to a lesser degree β-lactoglobulin synthesis by bovine mammary cells in culture. Individually increasing each of the 13 amino acids in MEM 3-fold showed cystine followed by threonine and then methionine significantly (P < .05) increased the combined synthesis of β-casein and β-lactoglobulin. The correlation between intracellular pool size change and the response in milk protein synthesis to increased individual amino acids was -.51 which was not significant at the .05 level. / Ph. D.

Thesis (MPhil (Animal Sciences. Aquaculture))--University of Stellenbosch, 2006. / Chemo-attraction and –stimulation facilitate the initial location (olfactory response) and final consumption (gustatory response) of food in the feeding process of fish. Chemo-attractants or chemo-stimulants is therefore generally included in feeds for especially slow-feeding species to help reduce water fouling and to promote feed efficiency and growth rate through improved feed intake. Considering this, a study was performed to evaluate the attraction and stimulation potential of selected cereals and free amino acids in diets for Japanese koi carp (Cyprinus carpio). Results are presented on the comparative evaluation of five cereals (maize, sorghum, wheat, rye and triticale), raw and cooked forms of maize and concentrations of betaine and selected free amino acids (alanine, arginine, lysine and methionine), as well as their additive effect.

Thesis (MScAgric)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: The following study is to determine if a creep feed balanced for limiting essential amino acids (EAA) at a certain non structural carbohydrate (NSC) level will elicit greater responses than lambs reared on a commercial creep feed. Lysine, Threonine, Methionine, Isoleucine, Phenylalanine and Leucine were determined as the limiting amino acids for nursing lambs. These amino acids were incorporated into the creep feed treatments CF1 and CF2 representing 157 g CP/kg, 477 g NSC/kg and 179 g CP/kg, 508 g NSC/kg, respectively. A commercial creep feed with no optimisation for EAA is represented as CFC with 139 g CP/kg and 455 g NSC/kg. A negative control (CON) treatment represents lambs receiving no creep feed but with ad libitum access to suckle their dams while feeding on kikuyu pasture. A growth trial was conducted on Merino x Döhne-Merino cross twin lambs averaging a birth weight of 4.42 kg ± 0.11 for 60 days following with a digestibility trial towards the end of the trial. Half of the lamb crop was slaughtered at an average live weight of 23.6 kg ± 0.56. The M. longissimus dorsi was removed on both the left and right half of the carcass between the 2nd - 3rd last thoracic vertebrae and the 4th - 5th lumbar vertebrae. A sample from the rumen wall was taken at the rumino-reticular fold to determine development characteristics. Results indicate that the feed conversion ratio for the CFC lambs were better than CF1 (P = 0.052) but not more than CF2 (P = 0.307). The FCR was 0.88, 1.19 and 1.01 (kilogram feed required to gain 1 kg in bodyweight) for CFC, CF1 and CF2, respectively. Dressing percentage was higher for CF2 than for both CFC (P = 0.012) and CF1 (P = 0.077). Along with BUN data it was concluded that the high CP level of CF2 resulted in the higher fat deposition. The optimised creep feeds had higher nitrogen and energy balances than the commercial CFC, this implicates that the optimised creep feeds were more efficiently utilised. Optimised creep feed treatments had longer papillae than CON (P < 0.0001). Papillae of creep feed 2 was longer than CFC (P = 0.0537). Papillae width decreased as the NSC level increased thus it is surmised that higher NSC levels resulted in longer but thinner papillae. Rumen muscularization was equally developed between all the treatments and was ascribed to the lambs’ access to course roughage. Meat quality in terms of physical and chemical characteristics was found to be in range with that expected for lambs at higher slaughter weights (40 kg). In conclusion, the balancing of the limiting EAA increases the benefits of creep feeding while simultaneously being more efficiently utilised. Intensive sheep production systems may benefit from the feeding of such creep feeds provided it fits economically into their farming system. / AFRIKAANSE OPSOMMING: Die volgende studie is om te bepaal of 'n kruipvoer wat gebalanseerd is vir beperkende essensiële aminosure (EAA) by 'n vasgestelde nie-strukturele koolhidraat (NSK) vlak verbeterde groei sal ontlok teenoor lammers wat grootgemaak word op 'n kommersiële kruipvoer. Lisien, Treonien, Metionien, Isoleusien, Fenylalanien en Leusien is bepaal as die beperkende aminosure vir suipende lammers. Hierdie aminosure is opgeneem in die geoptimiseerde kruipvoer behandelings CF1 en CF2 wat 157 g RP/kg, 477 g NSK/kg en 179 g RP/kg, 508 g NSK/kg onderskeidelik verteenwoordig. 'n Kommersiële kruipvoer met geen optimalisering vir EAA is verteenwoordig as CFC met 139 g RP/kg en 455 g NSK/kg. 'n Negatiewe kontrole (CON) behandeling is verteenwoordig deur lammers wat geen kruipvoer ontvang het nie, maar wat ad libitum toegang tot hul ooi gehad het om te soog terwyl die ooi op ‘n kikoejoeveld wei. 'n Groei proef is uitgevoer met Merino x Döhne-Merino kruis tweelinglammers met ‘n gemiddelde geboorte gewig van 4,42 ± 0,11 kg vir 60 dae en 'n verteerbaarheids proef is na aan die einde van die studie uitgevoer. Helfte van die lam kudde is geslag by die lewende gewig van 23,6 ± 0, 56 kg. Die M. longissimus dorsi was op beide die linker-en regter helfte van die karkas tussen die 2de - 3de laaste torakale werwels en die 4de - 5de lumbale werwels verwyder. 'n Monster van die rumen wand is geneem langs die rumino retikulêre vou sodat die rumen ontwikkeling eienskappe daarmee bepaal kon word. Resultate dui daarop aan dat die voeromsetverhouding (VOV) vir CFC lammers beter was as vir CF1 (P = 0,052), maar nie meer as vir CF2 (P = 0,307) nie. Die VOV was 0,88 , 1,19 en 1,01 (kilogram voer wat nodig is om 1 kg liggaamsmassa aan te sit) vir CFC, CF1 en CF2 onderskeidelik. Uitslag persentasie vir CF2 was hoër as beide CFC (P = 0,012) en CF1 (P = 0,077). Saam met die bloed, urea en stikstofbalans data is daar tot die gevolgtrekking gekom dat die hoë RP inhoud van CF2 gelei het tot ‘n hoër vetneerlegging. Die geoptimaliseerde kruipvoere het ‘n hoër stikstof- en energiebalans gehad teenoor die kommersiële CFC behandeling wat dus impliseer dat die optimale kruipvoere doeltreffender benut was. Die geoptimaliseerde kruipvoer behandelings het langer papillae gehad as CON (P < 0,0001). Papillae lengte van die CF2 behandeling is langer as die van CFC (P = 0,0537). Papillae breedte het dunner geraak soos wat die NSK-vlak gestyg het dus word vermoed dat hoër NSK-vlakke langer maar dunner papillae tot gevolg het. Rumen bespiering is ewe ontwikkeld tussen al die behandelings en word toegeskryf aan die lammers se toegang tot growwe ruvoer. Vleis kwaliteit in terme van fisiese- en chemiese eienskappe was inlyn met wat verwag kan word vir lammers by hoër slaggewigte (40 kg). Ten slotte, die balansering van beperkende aminosure verhoog die voordele van kruipvoeding en word terselfdertyd doeltreffender benut. Intensiewe skaap produksie stelsels kan dus voordeel trek uit die voeding van sodanige kruipvoere mits dit ekonomies pas in die boerdery stelsel.

Thesis (MScAgric)--Stellenbosch University, 2003. / ENGLISH ABSTRACT: 1. The effect of heat-treatment and dehulling of full-fat soya (Glycine max) on AMEn' amino acid availability and broiler performance. Heat treatment and dehulling of full-fat soya were evaluated in terms of their effect on AMEn, apparent amino acid availability and broiler performance. Four products were tested: raw whole soya (RWS), raw dehulled soya (RDS), extruded whole soya (EWS) and extruded dehulled soya (EDS). Trials were conducted to determine AMEn values and apparent amino acid availability of the products. A 42-day broiler trial was conducted to measure the effect of extrusion and dehulling on broiler performance. Test products were added to the diets at levels up to 263.2 g/kg in the starter diet and 260.0 g/kg in the finisher diet. Results indicated that extrusion cooking improved AMEn and apparent amino acid availability. This was reflected in the improved performance of broilers fed extruded soya as compared to raw soya. Increasing amounts of RWS and RDS led to decreases in mass and intake and poor feed conversion ratio (FeR) due to the presence of anti-nutritional factors. Broilers fed EWS were heavier, consumed more feed and had better FeR than those fed RWS or RDS. Dehulling improved AMEn (EWS: 13.75 MJ/kg vs EDS: 15.09 MJ/kg) and rendered a product with slightly higher levels of total amino acids. Broiler performance did not reflect this as there was no difference in mass, intake or FeR between broilers fed increasing levels of EWS or EDS. Lysine and arginine were less available in EDS than EWS indicating the possible over-cooking of EDS. Levels of EWS and EDS of 263.2 g/kg in the starter and 260.0 g/kg in the finisher supported maximum broiler performance. 2. The effect of heat-treatment and dehulling of full-fat sunflower (Helianthus annuus) on AMEm amino acid availability and broiler performance. Heat treatment and dehulling of full-fat sunflower were evaluated in terms of their effect on AMEn, apparent amino acid availability and broiler performance. Four products were tested: raw whole sunflower (RWSF), raw dehulled sunflower (RDSF), extruded whole sunflower (EWSF) and extruded dehulled sunflower (ED SF). Trials were conducted to determine AMEn values and apparent amino acid availability of the products. A 42-day broiler trial was conducted to measure the effect of expansion and dehulling on broiler performance. Test products were added to the diets at levels up to 115.0 glkg in the starter diet and 181.5 glkg in the finisher diet. Dehulling rendered a product with higher crude protein, ether extract, amino acid and AMEn values. AMEn was only slightly improved by expansion. The AMEn values obtained were: RWSF: 16.03 MJ/kg, RDSF: 18.87 MJ/kg, EWSF: 16.22 MJ/kg, EDSF: 19.49 MJ/kg. Dehulling had no effect on apparent amino acid availability. Expansion did not affect apparent amino acid availability of dehulled full-fat sunflower but had a negative influence on apparent amino acid availability of whole sunflower seeds. This highlights the possible dangers of reduced protein quality as a result of overprocessing. No differences were observed in terms of mass, intake and feed conversion ratio of broilers fed any of the products during the 42-day broiler growth trial. All products supported optimum broiler performance at levels up to 115.0 glkg in the starter diet. For the finisher diets, optimum performance was maintained at levels of 181.5 glkg, for RDSF and EDSF, while performance of broilers fed RWSF and EWSF was optimal up to 145.2 glkg. / AFRIKAANSE OPSOMMING: 1. Die invloed van hitte-behandeling en ontdopping van volvetsojabone (Glycine max) op SMEm skynbare aminosuur beskikbaarheid en braaikuikenprestasie. Hitte-behandeling en ontdopping van volvetsojabone is ge-evalueer in terme van hul invloed op stikstof gekorrekteerde skynbare metaboliseerbare energie (SMEn) waardes, skynbare aminosuur beskikbaarheid en braaikuikenprestasie. Vier produkte is getoets: rou heel sojabone (RWS), rou ontdopte sojabone (RDS), geekstrueerde heel sojabone (EWS) en geekstrueerde ontdopte sojabone (EDS). Proewe is uitgevoer om die SMEn waardes en skynbare aminosuur beskikbaarheid van die vier produkte te bepaal. Gedurende 'n braaikuikengroeitoets van 42 dae is die invloed van hittebehandeling (ekstrusie) en ontdopping op braaikuikenprestasie gemeet. Die vier toetsprodukte is ingesluit in die aanvangsdieet teen peile van tot 263.2 g/kg en teen peile van tot 260.0 g/kg in die afrondingsdieet. Resultate het getoon dat ekstrusie die SMEn waardes en skynbare aminosuur beskikbaarheid verbeter het. Braaikuikens wat geekstrueerde soja ontvang het, het beter gepresteer as braaikuikens wat rou soja ontvang het. Verhoogte insluitings van RWS en RDS het gelei tot verlagings in massa toename en voerinname en swak voeromsetverhoudings (VOV), as gevolg van die teenwoordigheid van anti-voedings faktore. Braaikuikens wat EWS ontvang het, was swaarder, het meer ingeneem en het beter vav gehad as die wat RWS of RDS ontvang het. Ontdopping het SMEn verhoog (EWS: 13.75 MJ/kg vs EDS: 15.09 MJ/kg) en ontdopte produkte het klein hoeveelhede meer aminosure bevat. Dit het egter nie in braaikuikenprestasie gewys nie. Daar was geen verskille in massa, voerinname en vav tussen braaikuikens wat EWS of EDS ontvang het. Lisien en arginien was minder beskikbaar in EDS as EWS wat op die moontlike oorprosessering van EDS dui. Vlakke van EWS en EDS van 263.2 g/kg in die aanvangsdieet en 260.0 g/kg In die afrondingsdieet het maksimale braaikuikenprestasie ondersteun. 2. Die invloed volvetsonneblosaad van hitte-behandeling (Helianthus annuus) en ontdopping van op SMEo, skynbare aminosuur beskikbaarheid en braaikuikenprestasie. Hitte-behandeling en ontdopping van volvetsonneblomsaad is geevalueer in terme van hul invloed op stikstof gekorrekteerde skynbare metaboliseerbare energie (SMEn) waardes, skynbare aminosuur beskikbaarheid en braaikuikenprestasie. Vier produkte is getoets: rou heel sonneblomsaad (RWS), rou ontdopte sonneblomsaad (RDS), geekspandeerde heel sonneblomsaad (EWS) en geekspandeerde ontdopte sonneblomsaad (EDS). Proewe is uitgevoer om die SMEn waardes en skynbare aminosuur beskikbaarheid van die vier produkte te bepaal. Gedurende 'n braaikuikengroeitoets van 42 dae is die invloed van hitte-behandeling (ekspansie) en ontdopping op braaikuikenprestasie gemeet. Die vier toetsprodukte is ingesluit in die aanvangsdieet teen peile van tot 115.0 g/kg en teen peile van tot 181.5 g/kg in die afrondingsdieet. Ontdopte sonneblomsaad het hoer peile van ruproteien, eter-ekstrak en aminosure as heel sonneblomsaad. SMEn waardes is ook hoer vir ontdopte sonneblomsaad. Hitte-behandeling het SMEn waardes effens verhoog. Die bepaalde SMEn waardes is as volg: RWSF: 16.03 MJ/kg, RDSF: 18.87 MJ/kg, EWSF: 16.22 MJ/kg, EDSF: 19.49 MJ/kg. Ontdopping het geen invloed op skynbare aminosuur bekikbaarheid gehad nie. Skynbare aminosuur beskikbaarheid van ontdopte sonneblomsaad IS me deur hitte-behandeling beinvloed nie, terwyl die van heel sonneblomsaad negatief beinvloed is. Dit beklemtoon die gevare van verswakte proteien kwaliteit as gevolg van oor-prosessering. Geen verskille is opgemerk in terme van massa, voerinname en voeromset verhouding (VOV) tussen die vier produkte gedurende die braaikuikengroeitoets van 42 dae. Alle produkte het maksimale braaikuiken prestasie ondersteun in die aanvangsdieet teen vlakke van 115.0 g/kg. In die afrondingsdieet het RDSF en EDSF optimale braaikuikenprestasie onderhou teen vlakke van 181.5 g/kg, terwyl RWSF en EWSF net t

Thesis (PhD(Agric) (Animal Sciences))--University of Stellenbosch, 2006. / This project consisted of five studies. The objectives were to determine the essential amino acid (AA) requirements of growing woolled lambs (Merino and Dohne Merino) and the essential AA profile of duodenal digesta pre-dominantly derived from microbial protein. The limiting essential AA`s in high rumen degradable protein (RDP) diets to growing lambs, where microbial protein is the primary source of AA`s, were also identified. The first study determined the essential AA profile of duodenal protein on a high rumen degradable diet and evaluated the impact of dietary RDP concentration and source [true RDP vs. non-protein nitrogen (NPN)] on the AA composition of supplied in the duodenum. The first trial in this study evaluated the effects of increasing true RDP levels on the essential AA composition of duodenal protein primarily derived from rumen microbes. The lambs had free access to wheat straw and fresh water. The daily RDP supplements were administered in two equal doses into the rumens through rumen cannulas at 07:00 and 19:00. Duodenal digesta was extracted with 6h intervals through T-type cannulas, inserted proximally to the common bile duct. Sampling time was advanced 2h every day to obtain duodenal samples on every even hour of a 24h period after three days. As expected, deficient RDP limited the supply of essential AA`s in the iv duodenum. When the true RDP supplements increased, the duodenal flow of essential AA`s also increased concomitantly, but appeared to level off at the higher RDP levels. Despite the positive quantitative effects of true RDP supplementation on AA supply to the duodenum, the AA profile in the duodenum was unaltered. Consequently, the essential AA profile of duodenal protein of sheep receiving high RDP diets, where microbial protein is the primary source of AA`s in the duodenum, is relatively constant and insensitive to dietary RDP concentration. In the second trial the effects of RDP source (true RDP vs. NPN) on the essential AA profile of duodenal protein on high RDP diets were evaluated by substituting increasing amounts of urea for true RDP in isonitrogenous teatments. Higher NPN increments reduced the daily supply of essential AA`s in the duodenum. In corroboration of the first trial, the AA profile of the duodenal protein was very constant, irrespective of the RDP source. Since microbial protein is the major source of duodenal AA`s on high RDP diets, this study supports the view that microbial protein has a relatively constant AA profile, but microbial protein yield varies according to several rate limiting factors in the rumen. A constant microbial AA profile allows accurate estimates of microbial essential AA supply in the small intestine if microbial protein production and fluid and particulate outflow rates from the rumen can be accurately predicted. This allows the development of more accurate undegradable protein (UDP) supplementation strategies, based on the essential AA requirements of animals. In the second study growing male Merino and Dohne Merino lambs were slaughtered at different weights and body condition scores. The digesta was removed from the stomachs and intestines and every organ or body part were weighed to determine the whole empty body (WEB) composition. The WEB was partitioned into the carcass, internall offal (stomachs, intestines, organs and blood) and external offal (head, feet, skin and wool). No differences were apparent in the proportional weight distribution of similar body components of the same breed at different ages. In a comparison between breeds, the proportional weight contributions of the carcasses from both breeds to the WEB weight were remarkably similar at both slaughtering stages. The Dohne Merino lambs had proportionally larger internal offals and smaller external offals than the Merino lambs at both slaughters. Unless the essential amino acid compositions of the internal and external offals were identical to the carcass, the dissimilarities in weight and protein allocation to these two components within the WEB`s of Merino and Dohne Merino lambs imply a distinct WEB essential AA composition for each breed. The apparent digestibilities of dry matter (DM), crude protein (CP), energy, acid detergent fibre (ADF), neutral detergent fibre (NDF), fat and ash did not differ between Merino and Dohne Merino lambs. Energy retention was also similar for the two breeds, but the Merino lambs retained considerably more N than the Dohne Merino lambs. This may also impact on the respective amino acid requirements of the lambs. Since the Merino lambs utilise N more efficiently, they may have potentially lower essential amino acid requirements to achieve a similar growth rate. The WEB essential AA compositions of growing Merino and Dohne Merino lambs were determined in the third study. Based on the ideal protein concept, the WEB essential AA profile was accepted as representative of the AA requirements for growth. The use of a single body part as a representation of the WEB AA profile was also evaluated. Differences in the proportional weight and protein contribution of the three body components (carcass, internal offal and external offal) of the two breeds strongly suggested that the WEB AA composition of the breeds would differ, because of likely differences in the AA profiles of these components. The essential AA profiles of the carcasses from the two breeds were surprisingly similar. However, the essential AA compositions of the internal offal and external offal differed substantially from each other, as well as from the carcass. In addition, the internal offal and external offals of each breed had characteristic essential AA profiles. Inevitably, the WEB essential AA profiles of Merino and Dohne Merino lambs differed considerably. Only the leucine and phenylalanine concentrations in the WEB`s of Merino and Dohne Merino lambs did not differ. Significant differences in the concentrations of eight essential AA`s implied that the two breeds have different AA requirements for growth. The different AA compositions of the internal and external offal within each breed also illustrated that the use of a single body component, like the carcass, as a predictor of WEB essential AA composition contains considerable inaccuracies. The essential AA index indicated that the duodenal protein, primarily derived from rumen microbes, provided approximately 81 % of the qualitative AA requirements of growing lambs. During periods of sufficient availability of very low-quality forage, as the diet in this study simulated, microbial protein is not able to support maximum growth. The first two limiting AA`s (histidine and methionine) could not even support daily growth rates of 100 g/d. This is very low and stresses the need for effective undegradable AA supplementation under these conditions. Chemical scores identified histidine as the first limiting AA in high RDP diets (predominantly microbial protein), followed by methionine, leucine, arginine and phenylalanine. However, the requirements for histidine and arginine are frequently over estimated and these AA`s should actually be considered semi-essential, which could render methionine, leucine and phenylalanine the first three limiting AA`s to growing lambs receiving high RDP diets. Because of the limitations of static measurement systems for the determination of AA requirements, a more comprehensive evaluation method was introduced for determination of the limiting AA`s in duodenal protein of lambs on high RDP diets, in the fourth study. The fourth study focused on the identification of limiting AA`s to growing lambs being limit-fed a high RDP diet. The diet consisted primarily of soybean hulls, for its’ low rumen UDP content. Microbial protein production was calculated as 13 % of total digestible nutrient intake and complementary AA supplements prepared to simulate the WEB AA profile, determined in the previous study, in the small intestine. To eliminate the influence of the rumen on the AA supplements, the latter were infused into the abomasums via flexible tubing. Each essential AA was in turn removed from the control treatment (simulating the WEB composition) and the effect on N retention measured. When methionine or the branched-chain amino acids (BCAA`s) were removed from the infusate, N retention of the lambs was reduced. Consequently, methionine and at least one of the BCAA`s limited growth performance of young lambs when microbial protein was the predominant source of AA`s. The concomitant increased plasma concentrations of total AA`s when methionine or the BCAA`s were removed from the infusate corroborates the effects on N retention, since it indicates that AA utilisation was reduced when these AA imbalances were introduced. Amino acid imbalances had no effect on apparent DM, organic matter (OM) or NDF digestion, but N digestibility was reduced. The final study verified whether the BCAA’s were co-limiting the growth of lambs, or if any single BCAA was responsible for the limitation. Again the WEB AA profile of growing lambs was simulated in the small intestine via abomasal infusions to lambs receiving a soybean hull-based diet. Leucine, isoleucine and valine were individually or simultaneously removed from the infusate and the impact on N retention measured. On an individual basis valine had the largest negative impact on the efficiency of N utilisation. However, the simultaneous removal of the BCAA`s resulted in the lowest N retention, suggesting that valine might be limiting, but the three BCAA`s are more likely to be co-limiting in diets to growing lambs where microbial protein is the primary source of AA`s. Once again, neither DM, OM or NDF digestibility were affected by the AA imbalances. Nitrogen digestibility was, however, negatively affected by AA imbalances. This project succeeded in establishing the essential AA profile of duodenal protein in sheep receiving high RDP diets. The WEB essential AA compositions of growing lambs from two prominent sheep breeds in South Afica were then determined and the duodenal essential AA profile evaluated against the calculated AA requirements. Finally, the AA`s that limit growth in diets where microbial protein is the predominant source thereof were identified. These results contribute to the current knowledge of AA requirements in growing lambs, and highlight areas for future research, as discussed in the General Conclusion.

Calf scours are caused by a variety of infectious agents. Oral rehydration therapy solutions are formulated with the objective of correcting dehydration and acidosis. Currently, oral rehydraton therapy does not promote gut healing in diarrheic calves. However, investigators are examining the role of nutrition in promoting gut healing. Previous work has shown that the amino acid glutamine is important in nitrogen transport between tissues and is an indispensable nutrient for rapidly dividing cells such as lymphocytes, fibroblasts and enterocytes. Small intestinal epithelial cells depend mainly on glutamine, glucose, and ketone bodies for their energy under normal physiological conditions. The oxidative substrate preferred by large intestinal epithelial cells appears to be butyrate, followed by acetate, glutamine, and glucose. Research shows that glutamine supplementation increases intestinal protein synthesis. This may be one of the mechanisms by which glutamine exerts its protective effect on gut integrity and mucosal barrier function during critical illness. However, questions concerning the optimum dose and route by which glutamine is to be administered have yet to be addressed. A surgical model was developed to chronically study the nutrient concentration differences across the portal-drained viscera of preruminant calves. The experimental design consisted of a series of infusions conducted on four different study days in each calf. On the study days, 4 separate 1h infusions of acetate, glucose, glutamine, saline (control) were administered intravenously via the jugular vein at 200 mmol/L/h in a different order. Venous and arterial blood were collected over the last 15 min of each 1h infusion. Blood flow was also measured. Intestinal uptake in ìmol/kg^0.75/min was 0.3 ± 1.1 for glutamine and 1.9 ± 3.1 for glucose during saline infusion. During acetate, glucose, and saline infusions, glucose was a greater source of energy than glutamine for the intestine. However, during glutamine infusion, intestinal glutamine uptake (29.9 ± 11.2 ìmol/kg^0.75/min) increased significantly which was associated with a rise in ammonia production (7.0 ± 0.5 ìmol/kg^0.75min). A second experiment was designed to determine if glutamine uptake could be further stimulated either by longer term intravenous infusion or by chronic oral supplementation in neonatal calves. Intestinal metabolism was investigated by measuring nutrient uptake during three intravenous infusions of glutamine over a 5 h period after an overnight fast. Prior to the first infusion, calves diet consisted of milk only. Diet was supplemented with oral glutamine for the second and third infusions. Glutamine was administered via the jugular vein at a rate of 200 mmol/L/h. Venous and arterial blood was collected in duplicate every hour for 5 h. Blood flow was also measured. During glutamine infusion, there was an absolute increase in PDV uptake of glutamine associated with a significant production of ammonia. Feeding glutamine orally did not alter the PDV glutamine uptake. Glutamine infusion did not increase the intestinal uptake of essential amino acids. Neither chronic oral supplementation with glutamine, or infusion for periods longer than an hour, further increased intestinal glutamine uptake. Arterial leucine concentration and intestinal uptake declined during glutamine infusion suggesting that its supply became limiting. Thus glutamine supplementation may require the provision of a mixture of amino acids to be effective.

Excessive dietary protein may affect MP use because of energetic costs of excreting excess N. Amino acids also may influence post-ruminal digestion. Therefore, two experiments were designed to evaluate the effects of MP intake and post-ruminal flow of AA on growth performance and pancreatic digestive enzymes. In experiment 1, treatments supplied different amounts of MP intake to cattle and the effects on growth performance and feeding behavior were evaluated. In experiment 2, duodenal infusion of glutamate or casein was examined and the effects on pancreatic enzymes were measured. Experiment 1 suggests that feeding steers 906 g MP/d in finishing diets supplied enough MP for the greatest growth performance and carcass characteristics. Interestingly, MP intake caused different responses on feeding behavior with greater effects on steers fed 626 and 1444 g MP/d. In experiment 2, casein infusion increased α-amylase activity but not trypsin activity. Glutamate did not influence pancreatic digestive enzymes.

Thesis (MScAgric) -- University of Stellenbosch, 2002. / ENGLISH ABSTRACT: Low quality roughage is often used in the Western Cape as the only source of roughage for the young growing ruminant. Production levels of these animals is unsatisfactory and therefore supplementation is required. It is necessary when small grains are fed to also include protein sources in the diets. For high production, these protein sources must also be protected against rumen degradation. Good results are reported with the treatment of sunflower oilcakemeal (SFOCM) with formaldehyde (0.86 g formaldehyde per 100 g protein). Protecting methionine with 2-methyl maleic anhydride results in an increase in wool production. This study looked at the effect on dry matter intake (DM-intake), wool production and live weight change with supplementing a low quality diet with urea, SFOCM and formaldehyde protected SFOCM (FSFOCM). These diets where also supplemented with no methionine, methionine and 2-methyl maleyl methionine (MMM). The DM-intake of total diet are increased (P<0.05) with the supplementing of oats straw and barley (1.1% of live weight) diet with SFOCM and FSFOCM (949 & 935 vs 848 gis/d). Supplementing MMM decreased (P<0.05) the DM-intake with 9 %. Supplementing FSFOCM increased (P<0.05) live weight change from 19 to 44 gis/d. Wool production are increased (P<0.05) with 38 % with supplementation of MMM. The apparent digestibility of crude protein (CP) of the urea diet are increased (P<0.05) by supplementing methionine when compared with no methionine supplementation (67.28 vs. 71.23 %). The apparent digestibility of crude protein (CP) of the SFOCM diet (63.71 and 64.96 vs. 70.15 %) and FSFOCM diet (66.39 and 66.26 vs. 70.89 %) are increased (P<0.05) by supplementing MMM when compared with no methionine and methionine supplementation. The apparent digestibility of fat of the SFOCM diet (61.01 and 65.65 vs. 48.33 %) and FSFOCM diet (60.93 and 63.83 vs. 38.14 %) are decreased (P<0.05) by supplementing MMM when compared with no methionine and methionine supplementation. The apparent nitrogen balance of the SFOCM diet (-0.15 and 5.41 vs. 4.62 gis/d) and FSFOCM diet (2.93 and 5.60 vs. 6.02 gis/d) are increased (P<0.05) by supplementing MMM when compared with no methionine and methionine supplementation. The DM- and CP-degradability of barley and DM-degradability of oats straw did not differ (P<0.05) between different protein treatments. The higher production with the supplementation of amino acids and proteins can be associated with more amino acids available in the lower digestibility tract and not as a result of better rumen function. / AFRIKAANSE OPSOMMING: Die benutting van strooi as 'n laegraadse ruvoer deur die jong groeiende herkouer is 'n algemene praktyk wat in die Weskaap toegepas word. Produksie is egter laag en aanvulling van beperkende voedingstowwe is dus noodsaaklik. Saam met kleingrane word proteïenbronne meestal as aanvulling gebruik. Vir hoë produksie is dit dikwels nodig om proteïen aan te vul wat teen ruminale afbraak beskerm word. Die formaldehiedbehandeling (0.86 g formaldehied per 100 g proteïen) van sonneblomoliekoekmeel (SBOKM) is alreeds baie suksesvol toegepas vir die beskerming van proteïen teen ruminale afbraak. Deur metionien met dimetielmaleïelsuuranhidried te beskerm, is wolproduksie verhoog. Die studie het die effek van aanvulling van ureum, SBOKM en formaldehiedbehandelde SBOKM (FSBOKM) saam met geen metionien, metionien en 2,3 - dimetielmaleïelmetionien (MMM) op droëmateriaal (DM) -inname, wolproduksie en liggaamsmassaverandering ondersoek. Die DM-inname van jong Merinohamels op 'n hawerstrooi en gars (1.1% van liggaamsmassa) dieet is verhoog (P<0.05) deur die aanvulling van SBOKM en FSBOKM (949 & 935 vs 848 g/s/d). Die DM-inname is egter met 9 % verlaag (P<0.05) deur aanvulling van MMM. Die aanvulling van FSBOKM het die liggaamsmassatoename verhoog (P<0.05) van 19 na 44 gIs/d. Wolproduksie is met 38% (P<0.05) deur MMM-aanvulling verhoog. Die skynbare verteerbaarheid van ruproteïen (RP) by die ureumbehandeling is verhoog (P<0.05) met metionienaanvulling teenoor geen metionienaanvulling (67.28 vs. 71.23%). By SBOKM (63.71 en 64.96 vs. 70.15%) en FSBOKM-behandelings (66.39 en 66.26 vs. 70.89%) is skynbare verteerbaarheid van RP verhoog (P<0.05) met MMM-aanvulling teenoor metionien- of geen-metionienaanvulling. By SBOKM (61.01 en 65.65 vs. 48.33%) en FSBOKM-behandelings (60.93 en 63.83 vs. 38.14%) is skynbare verteerbaarheid van vet verlaag (P<0.05) met MMM-aanvulling teenoor metionien- of geen metionienaanvulling. By SBOKM (-0.15 en 5.41 vs. 4.62 gIs/d) en FSBOKM-bahandelings (2.93 en 5.60 vs. 6.02 gIs/d) is skynbare N-balans verlaag (P<0.05) met MMM-aanvulling teenoor metionien- of geen-metionienaanvulling. Die effektiewe verteerbaarheid van DM en RP van gars en effektiewe verteerbaarheid van DM van strooi is nie beïnvloed (P>0.05) deur die aanvulling van proteïen nie. Die verhoogde produksie kan dus geassosieer word met 'n verhoogde voorsienning van aminosure in die SVK deur aanvulling en nie weens verbetering in die rumenfunksie nie.

Three experiments were designed to find the most efficient and cost-effective method of meeting the changing amino acid requirements of male and female pigs during the growing period, using the minimum number of feeds. Trial one involved 144, and trial two 192 commercial crossbred (Landrace x Large White) pigs, eight to a pen, with sexes separate. Trial three involved 24 commercial crossbred (Landrace x Large White) pigs and 24 Dalland pigs each penned separately. The amino acid requirements (g/d) for the pigs in all three trials were determined for male and female Landrace x Large White pigs, respectively, using the Pig Growth Model (EFO Software Natal, 1995). Parameter values used for males and females were: growth rate (B, Id) 0.0107 and 0.0120; protein at maturity (Pmat, kg) 39.0 and 28.0; and lipid at maturity (Lpmat, kg) 2.60 and 3.89 respectively. In trials 1 and 2 two iso-energetic (DE 13.8 MJ/kg) basal feeds were formulated; Basal A being a high crude protein (CP) (347g CP/kg) feed designed to meet the amino acid requirements of a male at 20 kg liveweight, while Basal B was a low protein feed (l34g CP/kg) designed to meet the amino acid requirements of a female at 88 kg, thus providing for the most- and the least-demanding pigs on the trial. In the third trial, two iso-energetic (DE 13.8 MJ/kg) basal feeds were again formulated; Basal A being a high crude protein (CP) (347g CP/kg) feed designed to be 20% higher than the amino acid requirements of a male at 20 kg liveweight, while Basal B was a low protein feed (l34g CP/kg) designed to be 20% lower than the amino acid requirements of a female at 88 kg, once again providing for the most- and the least-demanding pigs on the trial. Trials 1 and 2 began when the median weight of pigs in each pen reached 20kg, and were terminated at a pen median of 85 kg liveweight. In the third trial each pig was started on trial when it reached 20kg and was terminated at a weight of 85kg. The first trial involved a phase feeding schedule (20-40, 40-60 and 60-85kg liveweight). The two basal feeds were blended in different proportions to create three feeds per phase: lysine contents in each of the phases in Treatment 1 (TI) were: 11, 8.68 and 7.26g/kg; in T2 they were 9.93, 7.58 and 6.24g/kg; and in T3, 8.85, 6.48 and 5.22g/kg. From the analysis it was established that ADO and time to reach 85kg were the only variables to show significance. ADO exhibited a significant sex x treatment interaction. There were significant differences between treatments for time taken to reach slaughter weight. In addition to a treatment effect there was a sex x treatment interaction for time to slaughter weight. It was expected that males on Tl and females on T3 would exhibit the most efficient performance for their respective sex since these treatments were specifically formulated to meet their requirements. Midway through the trial the pigs contracted enteritis, this affecting the outcome of the trial by inhibiting the potential growth of the pigs. The results of the trial indicated that dietary protein level affected the time taken to reach slaughter weight. This led to the second trial where four treatments were applied. Three of the four treatments followed a fixed feeding schedule, making use of the two basal feeds and a 1: 1 blend of these. The fourth treatment followed a phase feeding schedule, differing between the males (20-65, 65-75 and 75-85 kg liveweight) and the females (20-35, 35-75 and 75-85 kg liveweight). This treatment also made use of the two basal feeds and a 1: 1 blend of these. From the analysis it was found that there were no significant effects of sex and no interactions between feeding treatments and sex; however, ADO, FI, FCE, back fat thickness, time taken to reach 85kg and cost/kg gain were all significantly affected by the feeding treatments. Carcass lean, carcass lipid and total body lipid were also significantly affected by the feeding treatment. This trial was conducted to determine the extent to which differences in growth rate, food intake and carcass lipid could be altered by dietary means. The effect of the level of feed protein was once again shown to be of importance when feeding growing pigs. The third trial was designed to test the efficiency with which two strains make use of the dietary protein supplied. Three treatments were applied: Tl was a choice-feeding treatment in which the pigs were offered the two basal feeds simultaneously. T2 and T3 followed a phase feeding schedule (20-40, 40-60 and 60-85kg liveweight). The two basal feeds were blended in various proportions to create three feeds per phase: the lysine contents in each of the phases in T2 were: 12.2, 10.0 and 7.26g/kg; and in T3 8.1, 6.7 and 5.1g/kg. There were significant sex effects as well as strain x feeding treatment interactions. All variables, ADG, FI, FCE, time taken to reach 85kg and cost/kg gain, with the exception of back fat thickness, showed significance. It was expected that the Dalland strain would perform better than the Cross strain; however, this was not the case, indicating the need for further research into the possibility of feeding according to the genetic makeup of the animal. The importance of meeting the amino acid requirements of the growing pig was evident when summarising the results of the three trials reported here. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2006.