Graduation date: 1992

Broiler production is an important animal production enterprise with potential to make high returns. Increasing feed efficiency and early body weight gain has always been a top priority in the broiler industry. The general objective of broiler nutrition is to maximise production performance and profitability . Nutrition is of major importance in raising chicken, and feed is a major input in poultry production systems, accounting for over 60% of total production costs in commercial poultry sector Renkema (1992). The cost of feed is therefore often a constraint especially in developing countries. For instance, Onyenokwe (1994) observed that high cost of feed ingredients in many African countries has caused many poultry farmers to abandon the industry. The continued rise in feed prices is due to competition for some of the ingredients with human e.g. sorghum, wheat and maize. Broiler farmers are therefore forced to use combinations of feed ingredients of low cost to obtain savings and avoid any further loss of profits. It is therefore important to give special attention to feed and feeding since the rate of feed consumption increases rapidly with advancing age of the birds and good nutrition is reflected in the bird's performance and its products. The profitability of a broiler enterprise depends on the efficient conversion of feed to meat. Broilers have the ability to convert the feeds into meat with a high efficiency. For instance Morris and Njuru (1990) reported that broilers have much higher daily rates of protein deposition than layer chicken strains. This implies that fast-growing strains would require greater daily protein intakes than slow-growing ones. In the past, the major criteria for assessing the performance of broilers has been growth rate and feed conversion ratio (FeR). Diet specifications and feeding programmes have been aimed at maximising these two parameters whereby overall flock performance is calculated based on the total weight of chicken produced from total feed deliveries. With the new developments in understanding of nutritional factors affecting broiler growth and carcass composition, it is now possible to apply sophisticated and yet efficient approaches to feeding broilers. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.

Thesis (M.S.)--University of North Carolina Wilmington, 2008. / Includes appendix. Title from PDF title page (viewed May 27, 2009) Includes bibliographical references (p. 69-73)

Thesis (M.S.)--University of North Carolina at Wilmington, 2005. / Includes bibliographical references (leaves: 90-97)

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.

Attempts to improve upon the crude protein feeding system have strived to characterize feedstuffs with respect to ruminal protein degradability. In vitro an in situ procedures fall short of this goal by not accounting for ruminal turnover. Six lactating cows, fitted with ruminal and duodenal cannulae, were utilized for in vivo determination of protein degradability by employing a double-marker system. Treatments were corn silage-based diets supplemented with 2:1 soybean meal:fish meal nitrogen (SF) or 1:2 soybean meal:fish meal nitrogen (FS) at levels of 15. 9 and 16.0 percent protein. Ruminal cobalt ethylenediaminetetraacetic acid (CoEDTA) infusions marked liquid phase (LP) digesta and Yb-soaked hay was used as a solid phase (SP) marker. Duodenal digesta was separated into SP and LP at 3000xg. Least squares means of LP flows did not differ for total, precipitable protein, or microbial nitrogen, for SF and FS. Total solid phase flow of dry matter was higher for FS (9.06 kg/d) than for SF (7.97 kg/d), although intakes did not differ. Milk composition and yield did not differ for FS and SF. Average daily gain was 0.12 kg/d for SF and 1:26 kg/d for FS. Whole-tract digestibilties were not different although rumen digestibility of dry matter was 24.9% for FS and 35.7% for SF, and duodenal recovery of N was 93.8% for SF and 107.5% for FS. Inclusion of a higher level of fish meal in the diet increased the proportion of feed proteins delivered to the small intestine, increasing weight gain while having no effect on milk production. / Master of Science

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.

Thesis (MScAgric (Animal Sciences))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: The objective of this study was to evaluate Dohne Merino sheep and Boer goats in terms of the degradable parameters of a high-fibre diet, a low-fibre diet and two vegetable protein sources commonly used in South Africa. Differences between species were evaluated following the potential differences within species. The feedstuffs used were those for the following diets: low-fibre diet (LF); high-fibre diet (HF); sunflower meal (SFM) oilcake; and soybean meal (SBM) oilcake. In the first trial, the digestible characteristics of the HF and LF diets were determined by means of a digestibility study. A 6 × 6 Latin square design was used to determine whether Dohne Merino sheep or Boer goat wethers differ regarding the digestibility characteristics of low- and high-fibre diets. The diets were fed once daily at 1.24 kg to all the wethers, which had ad libitum access to fresh water. Each period consisted of 10 days of adaptation and seven days of faecal and urinary sampling. The results indicated that the intake and digestibility characteristics of nutrients did not differ between sheep and goats. However, the different diets differed in terms of the nutrient intake and digestibility range of sheep and goats. The second trial was an in sacco degradability trial to determine the dry matter (DM) and crude protein (CP) degradability of the LF, HF, SBM and SFM diets. Six Dohne Merino and six Boer goat wethers were fitted with rumen cannulae so that they could be used in the trial. All wethers received the same basal diet. The samples were incubated in the rumen in polyester Dacron bags, with the bags being removed at intervals of 0h, 3h, 9h, 12h, 24h, 48h, 72h, and 96h for the LF and HF diets. All the oilcake was removed at intervals of 0h, 2h, 4h, 8h, 12h, 16h, 24h, 36h and 48h. The sheep and goats were found not to differ from one another in terms of effective degradability of any of the feedstuffs concerned. However, within species differences were observed. To establish a fully integrated outcome of degradability, the study described in the current thesis was structured in such a way that the in vitro trial ran parallel with the in sacco trial, being performed with the aid of a Daisy Incubator (ANKOM Technology Corp., Fairport, NY). Such a procedure was only adopted in relation to the SFM and SBM diets in order to evaluate their in vitro data in relation to the in sacco data. The same oilcake was tested in the case of both trials, with the composite sample of rumen liquid of four sheep or goats, which was used in the in sacco trial, also being used in the in vitro study. In the study, DM disappearance values were determined and fitted to a single-compartment model by means of an iterative least-square procedure in order to determine the DM and CP degradability parameters. The DM used in vitro or in sacco was compared, using the actual values obtained after 8h incubation, due to only a limited amount of residue being left after incubation. In the study, the in vitro method overestimated the digestibility of SBM by 37% to 39% and the digestibility of SFM by 17% to 20% compared with that found to occur in the in sacco method. In vitro DM disappearance values for all SBM samples were found to be higher than those that were detected in the SFM samples. The percentage of in vitro true digestibility parameters was also calculated. No significant differences were found between species for effective degradability, though differences were observed within species between the two substrates concerned. In conclusion, the sheep and goats used in the study were not found to differ in terms of digestion parameters when they were compared on different types of roughage or protein sources. However, within species differences were, indeed, found to occur. Sheep and goats digested the SBM better than they did the SFM. / AFRIKAANSE OPSOMMING: Die doel van hierdie studie was om te bepaal of Dohne Merino skape verskil van Boerbokke in terme van degradeerbaarheidsparameters van ‘n hoë vesel-, ‘n lae veseldieët en twee plantaardige proteïenbronne wat algemeen in Suid-Afrika gebruik word. Die verskille tussen spesies is ge-evalueer en daarna die potensiële verskille binne spesies. Die volgende grondstowwe is geëvalueer: ‘n laevesel-dieët (LF), ‘n hoëvesel-dieët (HF), sonneblom-oliekoekmeel (SFM) en sojaboon-oliekoekmeel (SBM). In die eerste proef is die degradeerbaarheidsparameters van die HF dieët en die LF dieët met behulp van ‘n verteerbaarheidstudie bepaal. Dohne Merino hamels of Boerbok kapaters was gebruik om te bepaal of skape en bokke verskil in terme van inname en degradeerbaarheid van voedingstowwe wanneer hul hoë- en lae vesel voere gevoer word. Al die hamels en kapaters het ad libitum toegang tot vars water gehad en hul was een keer per dag (1.24 kg) gevoer. Elke periode het bestaan uit ‘n 10 dag aanpassingsperiode en ‘n toegelate 7 dae vir mis- en urienmonster versameling. Die resultate het aangedui dat die inname- en degradeerbaarheidsparameters van nutriënte beinvloed word deur verskillende diëte binne spesies. Geen verskille is gevind tussen spesies wanneer daar hoë- en lae kwaliteit voere gevoer is nie. Die tweede proef was ‘n in sacco-degradeerbaarheidsstudie om te bepaal wat die droë materiaal (DM) en ruproteïen (RP) verteerbaarheidsparameters van die HF dieët, die LF dieët, die SBM en die SFM is. Ses Dohne Merino’s en ses Boer bokke met rumen kanullas is in die studie gebruik en al die diere het dieselfde basale dieët ontvang. Die monsters is in die rumen geïnkubeer in poliester dakronsakkies en die sakkies is verwyder na onderskeidelik 0 uur, 3 uur, 9 uur, 12 uur, 24 uur, 48 uur, 72 uur en 96 uur intervalle. Laasgenoemde intervalle was geldig vir die lae vesel- en hoëveseldieët. Die oliekoeke se intervalle het verskil en is verwyder na 0 uur, 2 uur, 4 uur, 8 uur, 12 uur, 16 uur, 24 uur, 36 uur en 48 uur. Daar was geen verskille tussen spesies in effektiewe degradeerbaarheid nie, alhoewel verskille voorgekom het binne spesies. Skape verteer veselagtige grondstowwe meer effektief terwyl bokke weer hoë proteïn bevattende grondstowwe beter verteer. Om ‘n volkome geïntegreede uitkoms van degradeerbaarheid te bewerkstellig is die in vitro proef en die in sacco proef gelyktydig gedoen. Die in vitro-degradeerbareheidstudie is met behulp van ‘n ANKOM Daisy Inkubeerder uitgevoer (ANKOM Tegnologie Korp., Fairport, NY) vir net die oliekoek behandelings. Gedurende die studie is dieselfde oliekoeke gebruik. ‘n Saamgestelde monster van die rumenvloeistof van vier van die skape of bokke wat vir die in sacco-studie gebruik was, is gebruik vir die in vitro-inkubasie van die monsters. DM verdwyningparameters is bereken en dan met ‘n interaktiewe kleinste kwadraat prosedure op ‘n een-kompartement model gepas om die in sacco DMdegradeerbaarheidsparameters te bepaal. Die DM verdwyning, na 8h inkubasie, was gebruik om die in vitro en die in sacco metodes met mekaar te vergelyk, weens ‘n beperkte residu na die afloop van die elke inkubasiestudie. Tydens die studie het die in vitro metode degradering oorskat in vergelyking met die in sacco metode. DM verdwyningswaardes vir al die SBM monsters was hoër in vitro as die SFM monsters. In die studie is die persentasie in vitro ware degradeerbaarheidswaardes bereken. Geen verskille is opgemerk tussen spesies vir effektiewe degradeerbaarheid nie. Daar was wel verskille binne spesies. Om af te sluit het dit voorgekom dat skape en bokke nie verskil aan degradeerbaarheidswaardes wanneer daar ‘n vergelyking was tussen verskillende vesels- en proteϊenbronne nie, alhoewel verskille voorgekom het binne spesies. Skape en bokke het SBM effektief beter verteer as SFM.

With the narrow margin of profit in the broiler enterprise, how can producers increase profit potential? It is not an easy task to answer this question since the net financial return depends on many factors; some are related to the animal, some to the feed, some to the environment and others are outside the production system, like availability and cost of labour and capital. Many researchers have attempted to improve the efficiency of the system using alternative management strategies and to develop a unified theory that could simultaneously evaluate all the relevant factors and the interactions between them. Simulation models are seen as the most promising means of moving this subject forward. Geneticists are continually improving the potential growth rate of broilers, yet there has been little change in feed specifications for these birds over the past few decades. Only recently has it been possible to make use of simulation models to optimise the feeds and feeding programs of modern broiler strains at a commercial level, but little testing of these programs has been carried out. What is needed is a thorough investigation of these models, which at present are based on an individual, as opposed to a population response. Modelling plays an increasingly important part in animal science and research as a way of organizing and evaluating the large body of existing knowledge. With the use of an accurate description of the potential growth rates of broiler genotypes, it is possible to make more efficient use of growth models which are becoming more abundant in the industry and which, in turn, enable the nutritionist or producer to predict the performance of animals when subjected to a given feed or feeding programme. The predictions made by most of the growth models now available are based on individual animals, and the results obtained may be inadequate in optimising the nutrient requirements of a broiler population because of the variation that exists in these populations. Variation in performance traits in broilers may be the result of variation in the genotype, in the environmental conditions within the house, and in the composition of the feed offered to the birds, and these sources of variation cannot all be accommodated in a model that simulates the food intake and growth of just one bird. But if variation is to be incorporated into growth models, it is necessary to ascertain the effects of variation in the various genetic parameters on the mean response of the population. A sensitivity analysis is useful in accomplishing this objective. Similarly, it is important to know what the optimum size of a simulated population should be, that takes account both of the accuracy of the simulation and the time taken to complete the exercise. This is especially important when optimisation routines are followed, as such calculations are time consuming. As a means of addressing these issues, simulation exercises were conducted using EFG Broiler Growth Model version 6 and EFG Broiler Optimiser Model version 1 (EFG Software, 2006) to determine: (a) whether it is worth generating a population when optimising feeds and feeding programs for broilers, rather than using the average individual, (b) the size of the population required to obtain an accurate estimate of the population response when optimising the feeding program for different objective functions, (c) the effect of changing the value of genetic parameters such as mature protein weight, rate of maturing, feathering rate and the maximum lipid:protein ratio in the gain on the optimum amino acid contents and nutrient densities of broiler feeds, and (d) the effect of variation in nutrient composition of different batches of feed, which have the same nutrient profile but different qualities of the main protein source, on broiler performance. A review of sources of variation in the nutrient content of poultry feed was conducted, and simulation exercises were carried out to determine to what extent broiler performance is affected by the segregation or breakage of pellets into small pieces at the time of delivery and along the feed conveyor within the broiler house, by the change in nutrient quality that might occur along the conveyor, and by the microclimates that develop in a longitudinally ventilated broiler house. The tendency in broiler marketing in most parts of the world is to sell broilers cut up, as portions or deboned after evisceration, rather than selling whole birds. Estimation of the growth rates of carcass parts is therefore of considerable importance if simulation models are to be useful in optimising the feeds and feeding programmes of broilers under different conditions. Allometric equations are used in the EFG broiler growth model to predict the weights of these carcass parts from the weight of body protein at the time. These equations are based on data collected many years ago, and it would be useful to determine whether they are still relevant in the face of announcements by the major broiler breeding companies that tremendous strides have been made in improving breast meat yield, for example, by judicious selection. For the purpose of this investigation it was important to determine to what extent the weights of the physical parts varied at the same body protein weight, thereby enabling a more accurate estimation of the variation that could be expected in these weights when developing a population response model. Towards this end, experiments were conducted to determine the effect of dietary protein content on the performance of Cobb and Ross broilers, including mortality and uniformity, and on the allometric relationships between the physical and chemical components of the body and body protein. The overall objective of these exercises was to address issues relating to the use of simulation models in predicting food intake and growth of broilers, in optimising the amino acid contents and nutrient densities of feeds for broilers, and in representing a population of broilers when the performance of only one bird is simulated at a time. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.

Breeding companies advertise their chickens as having been selected for heavier breast meat. However, when comparisons are made between strains, these are normally made at a common age, and under these conditions the heaviest birds will have the heaviest breast meat yield. More meaningful comparisons would be made by relating breast weight to body protein weight, as these are allometrically related. Two experiments were conducted to test the hypothesis that the allometric relationship for each body part is the same irrespective of strain, sex and feed protein content, i.e. that geneticists have not been successful in changing the allometric relationship between breast meat weight and body protein weight. In the first trial, three strains, two sexes and four feed protein levels were used to 6 weeks of age, and in the second, four strains, two sexes and three feed protein levels were used to 12 weeks. Birds were sampled weekly, and the weights of breast meat (no skin or bone) and the meat and skin of the thigh, drum and wing were recorded before determining the body protein content of each of 1526 broilers. The hypothesis could not be corroborated when the data from the two trials were combined so a further trial was conducted to determine the amount of lipid that is deposited in the meat and skin of each of the commercially important parts of the broiler, on the assumption that differences in lipid deposition between strains, sexes and feed protein levels in the various physical parts would assist in explaining the anomalies in the analyses. It was confirmed in the third trial that the small differences between the observed and predicted weights of the physical parts may be accounted for through varying amounts of lipid deposition in these parts, depending on strain, sex and feed protein level, which must be accounted for when using allometry to predict the weights of the physical parts of the broiler at different stages of growth. The data collected in this series of trials may be used to predict the weights of these physical parts more accurately than has been the case to date. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2009.