No description available.

No description available.

The problem of reduced appetite in ruminants fed silages persists but the factors responsible for reduced intake of silage have not been elucidated. This study was conducted with the objective of testing the hypothesis that ammonia loading in ruminants could suppress appetite. In a 5 x 5 latin square design, sheep were fed alfalfa silage (S), fresh alfalfa (FA), and FA with added equimolar amounts (450 mmol. kg$ sp{-1}$ feed DM) of NH$ sb4$Cl, NH$ sb4$HCO$ sb3$ and urea; the latter was infused directly into the rumen. The silage had a DM content of 33.1%, pH 4.4, and a lactic acid content of 4.3% of DM. Unfermented herbage had a pH of 5.5 and lactic acid content of 0.2% of DM. Digestibility of organic matter (OMD) exceeded 70% for both S and FA. Organic matter intake (OMI), digestible organic matter intake (DOMI), concentration of rumen NH$ sb3$, rumen pH, osmolality and volatile fatty acids (VFAs) did not differ (P $>$ 0.05) among treatment groups. The lack of differences among treatments may have been as a result of a failure to accentuate qualitative and quantitative differences between the FA and S and to raise ammonia in the rumen and peripheral blood to levels that could alter appetite.

No description available.

Call number: LD2668 .T4 1979 N87 / Master of Science

Call number: LD2668 .T4 1979 O43 / Master of Science

Call number: LD2668 .T4 1985 G677 / Master of Science

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.

In a series of indoor and outdoor experiments with young sheep, feed supplements having different protein content were investigated. The supplements were chosen as those likely to elicit different Protein:Energy (P/E) ratios in the nutrients absorbed by the animal. The objective was to identify and characterize those that would support faster growth rate, bigger and leaner carcass production for the meat market, in different seasons in Southern Victoria, Australia (35-37° South, 141-143° East). Throughout, the GrazFeed model provided a reference system chosen for prediction of performance, with which the results of grazing experiments could be compete. / Supplementary feeding experiments were undertaken in the field (Experiments 1 and 4) in seasonal periods in which the pasture base found to poorly support high growth rates of weaned lambs. These experiments were supported by nutritional studies in pens (Experiments 2, 3 and 5) and supplement effects were evaluated in terms not only of liveweight but carcase and meat characteristics. Supplements used were evaluated and selected for use in further experiments on the basis that they would provide additional metabolisable energy but also would differ in the amount and nature of the crude protein they supplied and thus deliver different balances of absorbed nutrients, in particularly different P:E ratios. / Fish meal, with a high content of rumen undegradable protein of high biological value was used in each of these experiments to provide a test of the hypothesis that slow ruminal degradation and additional protein digested in the small intestine can influence animal response. In Experiment 1 and the related pen Experiment 2, comparing a lower to a higher P (CP%):E(MJ/kg) ratio feeds (barley, 12:13 P:E ratio) to (fishmeal / lucerne meal, 1/2 w/w, 35:10 P:E ratio), barley resulted in higher fat and lower protein amounts deposited as carcass components (P<0.01). The animals consuming extra protein were larger, leaner and became more uniform as a flock in terms of the range in LW and fat content at slaughter than those provided with supplements that are classed as energy feeds. / In Experiment 3 a range of alternative protein rich feeds and composite supplements was assembled that are cheaper and more readily available than fishmeal, with the idea that different patterns of ruminal degradation, intra-ruminal N availability and amounts of RUP could be created that would be beneficial in terms of the overall animal response. The paths of rumen protein degradability was determined with nylon bag techniques, and this was used to select feeds for investigation in a field and indoor experiments, Experiments 4 and 5. / In Experiment 4, grazing animals supplemented with lupines; (P:E 32:12), fishmeal / wheat bran 1/2 w/w (P:E 35:12) and formaldehyde treatment protected sunflower meal / wheat bran 1/2 w/w (P:E 24:11) responded poorly to the supplements where quality and quantity of pasture was such that unsupplemented growth rates were predicted to be poor by the decision support model, GrazFeed. In this and the supporting pen Experiment 5, the liveweight gain, final weight and dressing percentage of all supplemented lambs were significantly better than those of control (grazing only) animals (P<0.05). High and low commencing LW animals responded to protein supplements differently when these were fed at 1% BW with ad libitum medium quality roughage diet in indoor conditions. The heavier subgroup of fish meal / wheat bran (P:E 35:12) animals were significantly fatter than the heavy subgroup of wheat bran (P:E 17:10) animals (P<0.001). Lighter subgroup of animals were leaner and became more uniform (less variable) in weight and composition as a flock. Both the heavy and the light liveweight subgroups of fish meal grew faster but were fatter at slaughter than any other sub-groups. Lightest lambs fed bran grew from 26 to 36 kg in 10 weeks and had the most suitable carcase with the lowest priced supplement tested in the experiment. / Though protein supplementation had a positive effect on lamb performance; the advantage of high RUP was not consistent or always statistically significant. Compared to the alternative protein rich feeds, fish meal showed no cost effective advantage. The consequence of this current or possible future market conditions for feeding strategies for high quality lamb production are considered.

Graduation date: 1998