Call number: LD2668 .T4 1979 L37 / Master of Science

Call number: LD2668 .T4 1965 B91 / Master of Science

Call number: LD2668 .T4 1965 M43 / Master of Science

No description available.

The purpose of this study was to evaluate the feed value of Leucaena leucocephala (Lam) De Wit, as a renewable protein supplement for low-quality forages. Eight trials were conducted at the University of Pretoria experimental farm in Hatfield and the Agricultural Research Council experimental farm in Roodeplaat. The overall results showed that Leucaena leucocephala is a suitable protein supplement for low-quality forages. The chemical composition showed that Leucaena leucocephala forage has adequate potential nutrients. The rate of nitrogen degradation in the shoot was much slower and to a lesser extent than in mature pods with seeds, while the dry matter in the shoot degraded faster and to a greater extent than in the pods. In comparison with other forages (Lucerne, Eragrostis and Veld grass), Leucaena forage experienced a time lag of 6 hours before nitrogen could start degrading unlike the other three forages which did not have time lags. However, the dry matter in Leucaena forage did not experience any time lag, which gave Leucaena forage the best performance among the four forages. Lucerne on the other hand, had more readily available RDP, while Leucaena had more UDP. The effect of supplementing low-quality forages with varying levels of Leucaena forage was that the combinations between Leucaena and Veld grass gave better performance than the combinations between Leucaena and Eragrostis grass. Crude protein is the limiting factor in the performance of low-quality forages. Therefore, the supplementation of low-quality forage with Leucaena resulted in higher feed intake, digestibility and passage. The addition of Browse PlusTM increased the daily feed intake, the production of rumen ammonia and volatile fatty acids significantly. However, it did not have a significant effect on the rumen environment and the proportions of volatile fatty acids. The incubation and colour detector methods for the detection of Synergistes jonesii bacteria in the rumens of sheep were found to be simple, reliable and fast. It was confirmed that Synergistes jonesii bacteria can persist for more than four months in the rumens of sheep through autumn and winter drought without Leucaena forage in the diet. It was also shown that seasons have an influence on the level of mimosine in Leucaena forage. Hence, it was recommended that the forage has to be utilised fresh in summer when the level of mimosine is lower to minimise the risk of toxicity. / Agriculture, Animal Health and Human Ecology / D. Phil. (Environmental Science)

Thesis (MScAgric)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: The purpose of this study was to determine the essential amino acid requirements of beef cattle under feedlot conditions through evaluation of the duodenal and whole empty body essential amino acid compositions. To define the ideal protein required for growth, the whole empty body essential amino acid compositions of 8 beef steers (Simmental and Hereford crosses) was investigated. The amino acid composition of the components (carcass, metabolic organs and residual fraction), was pooled relative to their respective mass and protein contribution, resulting in the calculated whole empty body amino acid composition: arginine 6.81; histidine 2.69; isoleucine 4.02; leucine 6.96; lysine 7.43; methionine 2.01; phenylalanine 4.03; threonine 4.01; valine 5.30; tryptophan 0.82. Variations in profiles were found between scientific reports, either indicating that ratios change with growth and implants or possibly through genotype. The present study's body amino acid ratios were used to estimate dietary amino acid requirements through evaluation of the duodenal essential amino acid compositions from three different maize based feedlot diets. Although there was a general increase in the biological value of protein after rumen fermentation, the duodenal essential amino acids in comparison with the whole empty body recorded deficient/unbalanced profiles of essential amino acids for growth. The chemical scores suggested that the first-to-thirdlimiting amino acids in the duodenal digesta of beef cattle, that received three different commercially available feedlot diets, were: histidine, lysine, methionine/arginine (Diet 1), histidine, arginine, lysine (Diet 2) and arginine, methionine, histidine (Diet 3). Thedisproportionate duodenal amino acid concentrations obtained from the three diets, emphasise the necessity to enhance the intestinal delivery of amino acid profiles through different undegradable protein sources, with the objective to maximise protein utilisation and obtain the genetic potential for optimal growth in feedlot cattle. When amino acid requirements and flows to the duodenum were simulated using the Cornell Net Carbohydrate and Protein system (CNCPS), predictions indicated that lysine amino acid flow was limiting the metabolizable allowable average daily gain in Diet 1 and 3. Predicted profiles indicated that the order of limitation was: lysine, arginine, histidine (Diet 1), lysine, arginine, histidine, methionine (Diet 2) and lysine, arginine, histidine (Diet 3). The predicted profiles were in accordance with observed duodenal values, except for methionine that was observed limiting in Diet 1 and 3; however, the sequence and extent of limitation varied. Results indicate that prediction models have potential in predicting requirements; however there are still limitations for use to accurately define requirements for particular EAA's. From the present study, it is clear that the protein accretion was constrained by quantity and/or disproportionality of amino acids available for absorption. Further research should therefore be directed towards obtaining a more desirable array of amino acids to the lower digestive tract that is digestible, absorbable and an economically viable option for the feedlot operator. / AFRIKAANSE OPSOMMING: Aminosuurbehoeftes van Voerkraalbeeste Volgens die Duodenale en Totale Lee Liggaam Essensiele Aminosuur Profiel: Die doel van hierdie studie was om die essensiele aminosuur vereistes van vleisbeeste onder voerkraal toestande te bepaal deur die evaluering van die duodenale en totale lee liggaam essensiele aminosuursamesteilings. Om die idea Ie proteiene wat vir groei benodig word te definieer, is 'n ondersoek ingestel na die totale lee liggaam essensiele aminosuursamesteilings van 8 vleisbees osse (Simmetailer en Hereford kruise). Die aminosuursamesteiling van die komponente (karkas, metaboliese organe en residuele fraksie), se massa en proteien bydrae is gebruik om die totale lee liggaam aminosuursamestelling 5005 volg te bereken: arginien 6.81; histidien 2.69; isoleusien 4.02; leusien 6.96; lisien 7.43; metionien 2.01; fenielalanien 4.03; treonien 4.01; valien 5.3; triptofaan 0.82. Variasies in profiele tussen wetenskaplike verslae is gevind. Dit dui daarop dat groei en inplantings of moontlik genotipe 'n invloed op profiele kan he. Die huidige studie se liggaam aminosuurverhoudings is gebruik om die dieet aminosuurbehoeftes te skat deur evaluering van die duodenale essensiele aminosuursamesteilings van drie verskiilende mielie-gebaseerde voerkraal diete. Alhoewel daar 'n algemene toe name in die biologiese waarde van die proteien na rumen fermentasie was, het die duodenale essensiele aminosure in vergelyking met die totale lee liggaam, ongebalanseerde profiele van essensiele aminosure vir groei getoon. Die chemiese teilings toon aan dat die eerste-tot-derde-beperkende aminosure in die duodenale inhoud van vleisbeeste wat drie verskillende kommersieel beskikbare voerkraal diete ontvang het, soos volg is: histidien, lisien, metionieniarginien (Dieet 1), histidien, arginien, lisien (Dieet 2) en arginien, metionien, histidien (Dieet 3). Die ongebalanseerde aminosuur konsentrasies wat in die duodenum van die drie dlete verkry is, beklemtoon die noodsaaklikheid om die intestinale lewering van aminosuurprofiele te verbeter deur verskillende nie-degradeerbare proteien bronne te voer. Die doelwit moet wees om proteien verbruik te optimaliseer en daardeur die genetiese potensiaal vir optimale groei in voerkraalbeeste te bereik. Met die simulering van aminosuurbehoeftes en vloei na die duodenum van die drie standaard voerkraal diete met behulp van die "Cornell Net Carbohydrate and Protein System" (CNCPS), het voorspellings gewys dat lisien aminosuurvloei die metaboliseerbare toelaatbare gemiddelde daaglikse toename in Dieet 1 en 3 beperk het. Voorspelde profiele wys dat die volgorde van beperking soos volg sou wees: lisien, arginien, histidien (Dieet 1), lisien, arginien, histidien, metionien (Dieet 2)' en lisien arginien, histidien (Dieet 3). Die voorspelde profiele was in ooreenstemming met die waargeneemde duodenale waardes, behalwe vir metionien wat beperkend was in Dieet 1 en 3; die volgorde en mate van beperking was egter verskillend. Resultate wys dat voorspellingsmodelle die potensiaal het om behoeftes te voorspel. Vir die akkurate definisie van behoeftes vir spesifieke essensiele aminosuure is daar egter nog beperkinge. Uit die huidige studie, is dit duidelik dat protetenneerleqqinq deur die hoeveelheid en/of oneweredigheid van geabsorbeerde aminosure beperk is. Verdere navorsing moet dus fokus op die verkryging van In meer geskikte profiel van aminosure wat verteerbaar, opneembaar en 'n ekonomiese lewensvatbare opsie vir die voerkraalbestuurder is.

Thesis (MScAgric)--Stellenbosch University, 2001. / ENGLISH ABSTRACT: The goat is a significant domestic animal throughout the world today. With an estimated world goat population of 590 million goats in 1991 (FAO, 1991 as citied by Haenlein, 1996) it is impossible to consider the goat as insignificant. The need for milk, and it seems particularly goat’s milk, is obvious if one considers the increase in dairy goat populations over the past 20 years. Across the globe the dairy goat population has increased by 52% while in developing and developed countries, there has been an increase of 56% and 17%, respectively (Haenlein, 2000). The goat dairy industry in South Africa is still very underdeveloped, yet it holds tremendous potential for the entrepreneur willing to take the risk and do the job correctly. With the present South African financial situation the opportunities that exist for exporting value added products to countries with stronger currencies is a market with extraordinary potential. In New Zealand, the national herd consists of approximately 16000 dairy goats and 90% of the milk produced is turned to powdered milk and then exported to the East, a valuable source of foreign currency. In South Africa, the same potential exists and with some vision and hard work the dairy goat industry can make a valuable contribution to generating foreign currency. Research into the protein requirements and particularly protein degradability requirements of dairy goats is scarce, yet in recent years there has been an increased interest in the effect of protein supplementation to lactating animals (Mishra & Rai, 1996). In the work of Mishra & Rai (1996) there were benefits obtained from the use of different rumen degradable proteins for lactating dairy goat does. The does on the highly degradable protein diet had a better feed intake while the does on the low degradable protein diet gave a higher milk production. Other research on this field of study has also delivered positive results with more than one species of lactating animal that had increased levels of UDP in the diet (Robinson et al., 1991 and Christensen et al., 1993). Loerch et al. (1995) suggested that improved production by making use of rumen undegradable proteins would have no effect if crude protein were not a limiting factor in production. Pailan & Kaur (1995) and Mishra & Rai (1996) did research on lowered CP levels with increased UDP levels in lactating dairy does. They used of three diets, with the one having a 20% lower CP value but an increased level of UDP (40-45% of total CP). From this work it was concluded that a decreased CP level and an increased level of UDP is able to sustain production when compared with diets with a higher CP value. The current study consists of two trials. In the first trial the effect of weaning age and dietary protein degradability on the growth of Saanen kids was investigated. In the second trial the effect of dietary protein degradability on the production of lactating Saanen does was investigated. Fifty-eight Saanen kids were divided into groups to determine the effect of weaning age (42 vs. 70 days) on animal performance. Within the weaning day treatments, the kids were again divided into two dietary treatments. One group received a low UDP creep diet (LC) and the other a high UDP creep diet (HC). The two creep diets were formulated with rumen degradable: undegradable protein (RDP : UDP) ratios of 70:30 and 60: 40, referred to as LC and HC, respectively. However, the results from the degradability trial indicated no difference in RDP: UDP ratios for the low and high creep (72:28 and 73:27 respectively) diets. At 15.66 ± 3.09 kg the kids were taken off the creep diet and put on the growth diet. At this transition, the kids in each of the 4 established treatments were again randomly divided into two dietary treatments, a high or a low UDP growth diet, resulting in a total of eight treatments for the trial. The two growth diets were formulated with RDP: UDP ratios of 70:30 and 60:40, referred to as low growth (LG) and high growth (HG) respectively. Results from the degradability trial indicated RDP: UDP ratios for the LG and HG of 73:27 and 68:32 respectively. The growth trial was conducted over 140 days and feed intake, bodyweight change and feed conversion efficiency were compared for each of the 8 treatments. From the trial with the Saanen kids it was concluded that weaning dairy goat kids at 42 days of age when feed intake was 240 g/day resulted in similar growth rates when compared with weaning at 70 days. The two creep diets did not differ in RDP: UDP ratios and thus no conclusion can be made regarding the influence of the creep diets on the growth of Saanen kids from 20 to 80 days of age. The two growth diets did in fact differ from one another, in terms of RDP: UDP however, protein degradability had no influence on the performance of the Saanen kids from 80 to 140 days of age. Twenty-one lactating Saanen does were randomly assigned to one of three experimental diets. The treatments had two RDP: UDP ratios and two crude protein (CP) levels. Treatments were formulated to be 1) RDP: UDP = 70:30, CP = 20 % 2) RDP: UDP = 62:38, CP = 20% and 3) RDP: UDP = 62:38, CP = 18.3%. In the production trial the does were milked for 120 days, during which milk yield, milk composition, bodyweight change, feed intake and feed conversion efficiency were compared between the treatments. In the digestibility and nitrogen metabolism trial, 18 does varying from 84 to 110 days in lactation, were used to compare the experimental diets. Furthermore, the experimental diets were compared in a degradability and rate of passage trial using cannulated Dohne merino wethers. Results from the degradability trial indicated that the low UDP, low protein high UDP and high UDP diets had RDP: UDP ratios of 82:18, 78:22 and 79:21 respectively, and that the dietary protein degradability did not differ significantly between diets. Results from the production trial indicated that there was a significant difference in feed intake, dry matter (DM) intake and bodyweight. The does on the low UDP diet had significantly higher feed intakes and DM intakes and were significantly heavier at the end of the trial period. As the diets didn’t differ in protein degradability other factors must have influenced the intakes between diets. Palatability may have influenced feed and DM intake, as the low protein high UDP and high UDP diets both contained higher levels of fishmeal. No significant differences in milk production, milk composition or milk production efficiency were observed. Besides the fact that the diets did not differ in effective protein degradability, large variations in milk production between animals and low numbers of animals per treatment limited the ability to measure a difference between the treatments. Results from the digestibility trial varied between diets with the low UDP diet having a significantly lower digestibility overall than the other two diets. Reasons for the difference in digestibility could be due to the difference in rate of passage (low UDP = 0.064/hour versus the 0.044- 0.045/hour of the low protein and high UDP diets respectively) and the high ADF value of the low UDP diet. Because no difference in effective protein degradability existed between the diets it is not possible to make an accurate conclusion on whether or not the dietary protein degradability had an influence on production parameters tested in this trial. / AFRIKAANSE OPSOMMING: Huidiglik is die bok ‘n belangrike gedomestikeerde dier dwarsoor die wereld. Aangesien die wereldwye bokpopulasie in 1991 op 590 miljoen geraam is (FAO, soos aangehaal deur Haenlein, 1996), is dit onmoontlik om die bok as onbelangrik te beskou. Die behoefte aan melk, en dan veral bokmelk, is duidelik as mens die toename in bokpopulasies oor die afgelope 20 jaar in ag neem. Wereldwyd het die melkbokpopulasie met 52% toegeneem, terwyl dit in ontwikkelende en ontwikkelde lande met 56% en 17% onderskeidelik, toegeneem het (Haenlein, 2000). Ten spyte van die feit dat die bokmelk-industrie in Suid-Afrika nog baie onderontwikkel is, is daar geweldige potensiaal vir die entrepeneur wat bereid is om ‘n risiko te loop en die taak korrek aan te pak. Binne die huidige Suid-Afrikaanse finansiele situasie bestaan daar veral geleenthede om waardetoegevoegde produkte na lande waarvan die wisselkoers sterker is, uit te voer. In Nieu Zeeland is die nasionale kudde ongeveer 16000 melkbokke en 90% van die geproduseerde melk word verwerk na poeiermelk en uitgevoer na die Ooste. In Suid-Afrika bestaan dieselfde potensiaal en met die korrekte visie en harde werk kan die melkbok-industrie ‘n belangrike bydra lewer om buitelandse valuta te verdien. Alhoewel navorsing aangaande die proteien-degradeerbaarheidsbehoeftes van melkbokke skaars is, bestaan daar die afgelope paar jaar ‘n toenemende belangstelling in die effek van proteien supplementering aan lakterende diere (Mishra & Rai, 1996). In die werk van Mishra & Rai (1996) is die voordele om verskillende rumen degraderende proteTenvlakke in lakterende melkbokke te gebruik, aangetoon. Ooie op ‘n hoogs degradeerbare prote'fen-dieet het beter voerinnames getoon, terwyl die ooie op ’n laag degradeerbare prote'fen-dieet hoer melkproduksies gelewer het. Navorsing van hierdie aard op ander lakterende spesies het ook positiewe resultate met ‘n toename in verbyvloeiprote'ien in die dieet gelewer (Robinson et al., 1991 en Christensen et al., 1993). Loerch et al. (1995) het voorgestel dat ‘n verbeterde produksie, deur gebruik te maak van verbyvloeiprote'fn, geen effek sal he as ruprote'fen (RP) nie ‘n beperkende faktor i.t.v produksie is nie. Beide Pailan & Kaur (1995) & Mishra en Rai (1996) het navorsing gedoen op die invloed van verlaagde RP-vlakke en verhoogde nie-degradeerbare protein (NDP) vlakke in die diete van lakterende melkooie. Daar is gebruik gemaak van drie diete, waarvan die een dieet ‘n 20% laer RPinhoud, maar ‘n verhoodge NDP-vlak (40-45% van totale RP) gehad het. Vanuit hierdie werk is die gevolgtrekking gemaak dat ‘n verlaging in RP-vlak en ‘n verhoging in NDP-vlak dieselfde produksie kan onderhou, soos met ‘n hoer RP-inhoud. Die huidige navorsing bestaan uit twee proewe. In die eerste proef is die effek van speenouderdom en dieet-prote'fen-degradeerbaardheid op die groei van Saanen-lammers ondersoek. In die tweede proef is die effek van dieet-proteien-degradeerbaardheid op die produksie van lakteerende Saanen melkbokke ondersoek. Agt-en-vyftig Saanen-lammers is verdeel in twee speenouderdom-behandelings, nl. ‘n 42 dae (42) en ‘n 70 dae (70) speenouderdom. Binne hierdie speenouderdom-behandelings is die lammers verder verdeel in twee dieet-behandelings. Die een groep het ‘n lae NDP kruiprantsoen (LK) en die ander ‘n hoe NDP kruiprantsoen (HK) ontvang. Die twee kruiprantsoene was geformuleer om rumen degradeerbare proteien (RDP): NDP verhoudings van 70:30 (LK) en 60:40 (HK) te bevat, maar die resultate van die degradeerbaarheidsproef het aangetoon RDP: NDP verhoudings van 77:23 (LK) en 78:22 (HK). Die lammers is vanaf die kruipdieet oorgeplaas op ‘n groeidieet by ‘n gemiddelde lewende massa van 15.99±3.09 kg. Tydens hierdie oorplasing is die lammers van die vier bestaande behandelings verdeel in ‘n verdere twee dieetbehandelings, nl. ‘n hoe of ‘n lae NDP groei-dieet (LG en HG onderskeidelik), met die gevolg dat ‘n totaal van agt behandelings in hierdie proef bestaan het. Die twee groeidiete is geformuleer met RDP: NDP verhoudings van 70: 30 (LG) en 60: 40 (HG) onderskeidelik, maar die resultate van die degradeerbaarheidsproef het aangetoon RDP: NDP verhoudings van 78:22 (LG) en 72:28 (HG). Die groeiproef is uitgevoer oor 140 dae en voerinname, verandering in liggaamsgewig en voeromsettingsdoeltreffendheid (VOD) is vergelyk tussen die agt behandelings. Uit die lammerproef is die gevolgtrekking gemaak dat boklammers wat op 42 dae gespeen is, wanneer voerinname 240g/dag is, soortgelyke resultate i.t.v. groeitempo lewer as lammers wat op 70 dae gespeen is. Die twee kruiprantsoene het nie van mekaar in RDP: NDP verskil nie en dus kan geen gevolgtrekking gemaak word omtrentdie invloed van dieet-protel'en-degradeerbaarheid op die groei van Saanen boklammers van 20 tot 80 dae ouderdom. Die twee groei diete het van mekaar verskil in RDP: NDP maar dieet-proteien-degradeerbaardheid het geen invloed op die groei van die Saanen boklammers van 80 tot 140 dae ouderdom gehad nie. Een-en-twintig lakterende Saanen-ooie is ewekansig in drie groepe. Die behandelings het twee RDP: NDP-verhoudings en twee ruprotei'en (RP) -peile ingesluit. Behandelings was 1) RDP: NDP = 70:30, RP = 20% 2) RDP: NDP = 62:38, RP = 20% en 3) RDP: NDP = 62:38, RP = 18.3%. Tydens hierdie produksieproef is die ooie vir 120 dae gemelk en die melkopbrengs, melksamestelling, verandering in liggaamsgewig, voerinname en VOD bepaal en vergelyk tussen behandelings. In die verterings- en stikstofmetabolismeproef is 18 ooie gebruik om die diete te vergelyk. Verder is die diete ook vergelyk in ‘n degraderings- en deurvloeitempoproef met gekannuleerde Dohne merino hamels. Dieet-proteien-degradeerbaardheid waardes verkry uit die degradeerbaarheidsproef het aangedui dat die bepaalde RDP: NDP verhoudings was 82:18, 78:22 en 79:21 vir die lae NDP, lae prote'fen hoe NDP en hoe NDP diete, en dat daar geen verskil in dieet-prote'fen-degradeerbaardheid was tussen die drie rantsoene. Resultate van die produksieproef dui daarop dat daar verskille in voerinname, droematerialinname, en liggaamsgewig tussen die drie rantsoene was. Die ooie op die laer NDP rantsoen het ‘n hoe voer en DM inname gehad en was swaarder na 120 dae in die proef as die ooie in die ander twee behandelings. Redes vir hierdie verskille is nie as gevolg van dieet-proteiendegradeerbaarheid nie. Die smaaklikheid kon dalk ‘n rol gespeel het omdat dat die twee hoe NDP rantsoene hoer vlakke van vismeel gehad het. Daar was geen verskil in melkproduksie, melksamestelling en melkproduksiedoeltreffenheid tussen die drie behandelings. Resultate van die verteringsproef het tussen die laer NDP-rantsoen en die ander twee rantsoene gevarieer. Die rede vir die verskil in verteerbaarheid mag wees a.g.v. verskillende deurvloeitempo’s (laer NDP = 0.064/uur teenoor 0.044 - 0.045/uur vir die laeproteien en hoe-proteienrantsoene) en die ADF waarde wat van die lae NDP rantsoen verskil het van die ander twee rantsoene. Omdat die resultate van die degradeerbaarheidsproef aangedui het dat daar geen verskil in dieet-proteiendegradeerbaardheid was nie is dit nie moontlik om ‘n gevolgtrekking te maak random die invloed van dieet-proteien-degradeerbaardheid op die produksie van lakterende Saanen melkbokke nie.

Thesis (MScAgric)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: Regardless of the extensive game eradication during most of the previous century, the game farming industry in South Africa has shown dynamic growth over the past few decades. Currently the approximately 8 000 game farms have a total income of more than R850 million per annum. Although there are various game species included in these farming enterprises, three of the most important species for commercial farming and meat marketing are springbok iAntidorcas marsupialisï, blesbok (Damaliscus dorcas phillipsiï and impala (Aepyceros melampus). Since nutrition is a key factor in the productivity of animals, any information on this subject is essential for the successful management of a game farm. However, apart from the general lack in applied research on game animals (due to the different approaches by biologists and agricultural researchers), there is also only limited information available on the nutritional requirements of game species or any of the aspects affected by nutrition. In order to address the above shortcomings in game animal nutrition, two separate studies were conducted. The purpose of the first study was to determine the physical body component and nitrogen (N) distribution in the springbok, blesbok and impala. The chemical composition of the three-rib cut was also compared with that of the carcass. Amino acid requirements for growth of the three game species were investigated in the second study according to the ideal protein concept. The essential amino acid (EAA) profile of the whole empty body of the three game species was compared with the EAA profile of the duodenal digesta in order to detect any imbalances for optimal growth. The same animals were used in both studies, namely eight of each of the three game species. Characterization of the physical body composition revealed that the dressing percentages (% of body weight; % of empty body weight) for the three game species were: springbok (57.1 ± 2.4 %; 64.0 ± 2.5 %), blesbok (50.2 ± 2.1 %; 62.8 ± 1.4 %) and impala (57.4 ± 2.2 %; 65.6 ± 2.0 %). The proportional distribution ofN between the carcass, external offal and internal offal was also determined. The mean carcass N concentration of the impala was higher (P<0.05) than that of the springbok and blesbok on a dry matter basis. According to the carcass chemical composition, the three game species seem to have a better potential for lean meat production (fat content of carcass 4.7-5.2 %) than domestic sheep (17-25 % fat). Male animals had a lower (P<0.05) fat and higher (P<0.05) moisture percentage in the carcass and threerib cut than the females. The fat correlation between the three-rib cut and the carcass on both an as-is and dry matter basis was significant across species and sexes. The protein content of the same cuts did, however, not yield a significant correlation on an as-is basis, and only the protein content of the springbok three-rib cut related (P<0.05) to that in the carcass on a dry matter basis. The second study concentrated on the nutritional requirements of springbok, blesbok and impala, and more specifically the EAA requirements. Differences (P<0.05) were found between the whole empty body EAA composition of the three game species. These differences were present whether protein quantity was included in the calculations (g AA/100 g crude protein) or not (expressed as % of lysine). The chemical scores indicated that the four most limiting amino acids (three for impala) in the duodenal digesta for whole empty body growth were: arginine, histidine, threonine and methionine (springbok); methionine, arginine, histidine and lysine (blesbok); and methionine, histidine and arginine (impala). Further disproportion of the amino acids in the duodenal digesta was present in excess levels of isoleucine (blesbok) and lysine, valine, leucine, threonine, isoleucine and phenylalanine (impala). The EAA:Lysine ratios of the whole empty body indicated a similar trend for the three game species. / AFRIKAANSE OPSOMMING: Die essensiële aminosuurbenodighede van springbok, blesbok en rooibok vir optimale groei: Ten spyte van die feit dat wild grootskaals uitgedun is gedurende die vorige eeu, het die wildboerdery-bedryf in Suid-Afrika oor die laaste paar dekades dinamiese groei getoon. Die totale inkomste van die ongeveer 8000 wildsplase beloop tans meer as R850 miljoen per jaar. Alhoewel daar verskeie wildspesies is wat by hierdie tipe boerdery ingesluit word, is die springbok (Antidorcas marsupialis), blesbok (Damaliscus dorcas phillipsi) en rooibok (Aepyceros melampus) van die belangrikste spesies vir kommersiële boerdery en vleisbemarking. Voeding IS 'n sleutelfaktor in die produktiwitieit van diere en daarom is emge inligting oor hierdie onderwerp noodsaaklik vir die suksesvolle bestuur van 'n wildsplaas. Afgesien van die algemene tekort aan toegepaste navorsing op wilde diere (as gevolg van die verskillende benaderings van bioloë en landboukundige navorsers), is daar ook slegs beperkte inligting beskikbaar oor die voedingsbehoeftes van wilde dierspesies of enige van die faktore wat deur voeding beïnvloed word. In 'n poging om bogenoemde tekortkominge in die voeding van wilde diere aan te spreek, is daar twee aparte studies uitgevoer. Die doel van die eerste studie was om die fisiese liggaamsamestelling en die stikstof (N) verspreiding in die springbok, blesbok en rooibok te bepaal. Die chemiese samestelling van die drie-ribsnit is ook met die van die karkas vergelyk. In die tweede studie is ondersoek ingestel na die aminosuurbehoeftes van die drie wildspesies deur van die ideale proteïen konsep gebruik te maak. Die bepaling van die essensiële aminosuurprofiel van die totale leë liggaam van die onderskeie drie wildspesies is bepaal en met die essensiële aminosuurprofiel van die duodenale-inhoud vergelyk, ten einde enige wanbalans vir optimale groei vas te stel. Dieselfde diere is in beide studies gebruik, naamlik ag springbokke, blesbokke en rooibokke. 'n Beskrywing van die fisiese liggaamsamestelling het aangetoon dat die uitslagpersentasies (% van liggaamsmassa; % van leë liggaamsmassa) van die drie wildspesies as volg was: springbok (57.1 ± 2.4 %; 64.0 ± 2.5 %), blesbok (50.2 ± 2.1 %; 62.8 ± 1.4 %) en rooibok (57.4 ± 2.2 %; 65.6 ± 2.0 %). Die proporsionele verspreiding van N in die karkas, uitwendige afval en inwendige afval is ook bepaal. Die gemiddelde N konsentrasie in die karkas van die rooibok was hoër (P<0.05) as die van die springbok en blesbok op 'n droë materiaal basis. Dit blyk vanaf die chemiese samestelling van die karkas dat die drie wildspesies 'n groter potensiaal het vir die produksie van maer vleis (vet-inhoud van karkas 4.7-5.2 %) as skape (17-25 % vet). Manlike diere het 'n laer (P<0.05) vetpersentasie en 'n hoër (P<0.05) vogpersentasie in beide die karkas en die drie-ribsnit teenoor die vroulike diere gehad. 'n Betekenisvolle korrelasie is tussen die persentasie vet in die drie-ribsnit en die karkas van al drie wildspesies en vir beide geslagte gevind, op beide 'n nat en droë materiaal basis. Die proteïeninhoud van dieselfde snitte was egter nie op 'n nat basis betekenisvol gekorreleerd nie, en slegs die proteïen-inhoud van die springbok se drieribsnit het verband gehou (P<0.05) met die in die karkas op 'n droë materiaal basis. Die klem van die tweede studie was op die voedingsbehoeftes van springbok, blesbok en rooibok, en meer spesifiek die essensiële aminosuurbenodighede. Daar is verskille (P<0.05) tussen die totale leë liggaam essensiële aminosuursamestelling van die drie wildspesies gevind. Hierdie verskille was aanwesig afgesien daarvan of die hoeveelheid proteïen in berekening gebring is (g aminosure /100 g ruproteïen) of nie (uitgedruk as % van lisien). Volgens die chemiese tellings was die vier mees beperkende aminosure (drie vir rooibok) in die duodenale-inhoud vir totale leë liggaamsgroei as volg: arginien, histidien, treonien en metionien (springbok); metionien, arginien, histidien en lisien (blesbok); en metionien, histidien en arginien (rooibok). Verdere wanbalanse in die armnosure van die duodenale-inhoud was aanwesig in die oormaat isoleusien (blesbok) en lisien, valien, leusien, treonien, isoleusien en fenielalanien (rooibok). Die verhouding van die essensiële aminosure tot lisien van die totale leë liggaam het by al drie wildspesies dieselfde tendens getoon.

11 pp. / This publication contains information about browse utilization by ruminant animals. It provides information about the rangelands in Arizona, the nutritional quality of browse, effects of drought and tannin and how to overcome them.

Total tract digestion coefficients for dry matter (DM) and neutral detergent fiber (NDF), passage rates for grain and roughage components of diets and liquid turnover were measured for 65 and 90% concentrate diets in separate 4 x 4 Latin square experiments using intact growing steers. Kinetics of in situ digestion for DM and NDF in diet ingredients, rumen pH, volume and DM distribution were determined in mature, rumen cannulated steers. Rates of passage and digestion were combined to calculate apparent extent of ruminal digestion (AERD) for diet ingredients. Diets were based on steam flaked milo. The control roughage was chopped alfalfa hay (AH). In 65% concentrate diets, chopped wheat straw (WS), bermudagrass straw (BS) or cottonseed hulls (CSH) replaced 50% of the AH. In 90% concentrate diets, all of the AH was replaced by WS, BS or CSH. Total tract starch digestion was not influenced by source of roughage at either concentrate level. In 65% concentrate diets, total tract digestion of DM and NDF was not adversely affected by substitution of WS for 50% of the AH. Digestion of these fractions was lower (P<.05) for BS and CSH diets, but the severity of depression was greatest (P<.05) for the CSH diet. Reduced digestibility of the CSH diet was attributed to lower digestibility of CSH in comparison with AH. Although WS and BS were also less digestible than AH, their inclusion in the diet improved (P<.05) AERD of DM and NDF from milo and AH. Improved AERD for NDF appeared to be related to the raft-forming properties of WS and BS, and their ability to maintain rumen pH in a more desirable range for NDF digestion. In 90% concentrate diets, effects of roughage source on utilization of milo were minimal. Total tract digestion of DM and NDF was lower (P<.05) for WS, BS and CSH diets than for the AH diet, because of dilution of the more digestible AH by these roughages. Wheat straw had a tendency to moderate ruminal pH and consequently might be more useful in high concentrate diets than roughages such as CSH and BS.