Thesis (Ph. D. (Animal Production )) -- University of Limpopo, 2013 / Eight experiments were conducted to determine the effect of dietary lysine to energy ratio on the productivity and carcass characteristics of indigenous Venda chickens aged one to thirteen weeks and raised in closed confinement. The eight experiments were based on four different energy levels of 11, 12, 13 and 14 MJ of ME/kg DM. Each dietary energy level had four different levels of dietary lysine (8, 9, 11 and 14 g lysine/kg DM). Thus, different dietary lysine to energy ratios were calculated. Experiments 1 to 4 determined the effect of dietary lysine to energy ratio on productivity of unsexed Venda chickens aged one to seven weeks. Each experiment commenced with 160 unsexed day-old indigenous Venda chicks with an initial live weight of 30 ± 3 g per bird and was carried out for seven weeks. In each experiment, the chicks were randomly assigned to four treatments with four replications, each having 10 chicks. A complete randomized design was used for each experiment. All data were analysed by one-way analysis of variance. Where there were significant differences, the Duncan test for multiple comparisons was used to test the significance of differences between treatment means. A quadratic regression model was used to determine the ratios for optimum productivity in each experiment while a linear model was used to determine the relationships between dietary lysine to energy ratio and optimal responses in the variables measured. Results indicated that dietary lysine to energy ratio for optimal responses depended on the variable of interest. In Experiment 1, feed intake, growth rate, live weight, ME intake and nitrogen retention were optimized at different dietary lysine to energy ratios of 0.722, 0.719, 0.719, 0.670 and 0.712, respectively. There was a positive and strong relationship (r2 = 0.950) between dietary lysine to energy ratio and feed conversion ratio (FCR). Results from Experiment 2 indicated that feed intake, growth rate, FCR, live weight, ME intake and nitrogen retention were optimized at dietary lysine to energy ratios of 0.719, 0.742, 0.788, 0.742, 0.734 and 0.789, respectively. In Experiment 3, dietary lysine to energy ratio did not have any effect (P>0.05) on all the parameters measured. However, quadratic analysis indicated that dietary lysine to energy ratios of 0.817, 0.883, 0.920, 0.898, 0.895 and 0.955 optimized feed intake, growth rate, FCR, live weight, ME intake and nitrogen retention of the chickens, respectively. Experiment 4 results showed that feed intake, growth rate, FCR, live weight ME intake and nitrogen retention were v optimized at different dietary lysine to energy ratios of 0.906, 0.964, 1.023, 0.966, 0.963 and 0.951, respectively. Experiments 5 to 8 determined the effect of dietary lysine to energy ratio on productivity, carcass characteristics, sensory attributes and haematological values of female indigenous Venda chickens aged eight to thirteen weeks. The layouts, treatments, design and execution were similar to those described for Experiments 1, 2, 3 and 4, respectively, except that Experiments 5 to 8 were for female indigenous Venda chickens aged eight to 13 weeks. These chickens were different from those used in Experiments 1 to 4. They were raised on a grower mash (16 % crude protein, 11 MJ of ME/kg DM and 180 g of lysine) prior to commencement of the study. Each experiment commenced with 120 eight weeks old female Venda chickens with an initial live weight of 412 ± 3 g per chicken. In each experiment, the chickens were randomly assigned to four treatments with five replicates, each having six chickens. Results obtained from Experiment 5 showed that feed intake, growth rate, FCR, live weight, ME intake, carcass weight, dressing percentage, breast meat, drumstick, wing weight, breast meat drip loss, juiciness, flavour, haemoglobin and pack cell volume were optimized at different dietary lysine to energy ratios of 0.672, 0.646, 0639, 0.649, 0.655, 0.656, 0.664, 0.669, 0.665, 0.663, 0.631, 0.708, 0.623, 0.556 and 0.609, respectively. In Experiment 6, the diets were formulated to have higher lysine to energy ratios than those in Experiment 5 by using a dietary lysine level of 9 g lysine/kg DM. Results from this experiment showed that feed intake, FCR, nitrogen retention, carcass weight, dressing percentage, breast meat, gizzard weights and breast meat pH at 2, 12 and 24 hours after slaughter were optimized at dietary lysine to energy ratios of 0.798, 0.613, 0.777, 0.742, 0.753, 0.729, 0.758, 0.752, 0.802 and 0.797, respectively. Red blood cell and haemoglobin values in this experiment were optimized at dietary lysine to energy ratios of 0.480 and 0.624, respectively. In Experiment 7, dietary lysine to energy ratios of 0.79, 0.85, 0.92 and 1.00 g lysine/ MJ of ME were used. Dietary treatments in this experiment had no effect (P>0.05) on all the production parameters measured except feed and apparent metabolisable energy intakes. Quadratic analysis of the results indicated that dietary lysine to energy ratios of 0.964, 0.912, 0.900, 0.890, 0.910, 1.090, 0.934 and 0.895 optimized feed intake, apparent metabolisable energy, carcass, breast meat, drumstick weights and vi breast meat drip loss, juiciness and flavour, respectively. A positive and very strong relationship (r2 =0.998) was observed between dietary lysine to energy ratio and pack cell volume. Experiment 8 diets were formulated to have higher dietary lysine to energy ratios than the other experiments. Results of this experiment indicated that all the production parameters were influenced (P<0.05) by dietary lysine to energy ratio except mortality. Feed intake, growth rate, feed conversion ratio, live weight, apparent metabolisable energy and nitrogen retention were optimized at dietary lysine to energy ratios of 0.996, 0.980, 0.991, 1.010, 0.957 and 0.993, respectively. Dietary lysine to energy ratios of 0.992, 0.974, 0.991, 0.992, 1.023, 0.981, 0.979 and 0.815 optimized carcass weight, dressing percentage, breast meat, drumstick, liver weights and breast meat tenderness, juiciness and flavour, respectively. There were variations in the optimal lysine to energy ratios for different parameters investigated. In a diet containing 8 g of lysine per kg DM, 11.13 MJ of ME/kg DM and 150 g of CP/kg DM, dietary lysine to energy ratios of 0.719 and 0.649 are recommended for optimal live weight of Venda chickens aged one to seven and eight to 13 weeks, respectively. In a diet containing 9 g of lysine per kg DM, 12.13 MJ of ME/kg DM and 180 g of CP/kg DM, dietary lysine to energy ratios of 0.742 and 0.712 are recommended for optimal live weight of Venda chickens aged one to seven and eight to 13 weeks, respectively. In a diet containing 11 g of lysine per kg DM, 12.51 MJ of ME/kg DM and 220 g of CP/kg DM, dietary lysine to energy ratios of 0.878 and 0.894 are recommended for optimal live weight of Venda chickens aged one to seven and eight to 13 weeks respectively. In a diet containing 12 g of lysine per kg DM, 12.05 MJ of ME/kg DM and 240 g of CP/kg DM, dietary lysine to energy ratios of 0.996 and 1.010 are recommended for optimal live weight of Venda chickens aged one to seven and eight to 13 weeks, respectively. The results obtained in this study showed that different production parameters of Venda chickens were optimized at different lysine to energy ratios. This implies that the nutritional requirements of these chickens are dynamic and thus, dietary lysine to energy for optimal production depends on the production parameter of interest. This has implications on ration formulation for indigenous chickens.

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Corrigenda inserted behind title page. Bibliography: leaves 275-306. The pattern of body growth and intestinal development of an Australian strain of broiler chicken, the Steggles x Ross (F1) in response to different diets was studied. Five experiments were designed to examine the pattern of growth and mechanisms involved. In four other experiments, the mechanisms underlying the gross response of the broiler chicks to dietary ingredients, anti-nutritive factors and growth enhancers were examined. Results indicated that a rapid development of the small intestine preceded significant overall body growth. Body growth would, however, depend more on the various physiological events such as those related to mucosal growth and renewal, digestive enzyme function, and nutrient transport. Some of the differences observed in productivity of broiler chickens on different diets were traced to events at the intestinal level.

Six experiments were carried out with Single Comb White Leghorn laying chickens to assess the effect of feeding a source of direct-fed microbials (Lactobacillus; Lacto) and its carrier [condensed cane molasses solubles (CCMS)] on the retentions of fat, nitrogen and several minerals; on the status of the pH of the gastrointestinal (GI) tract; on the phytase activities in the Lacto and in the crop and in the intestinal contents and intestinal, pancreatic and liver tissues; on the histological and anatomical changes of the GI tract and on the production performance. Feeding 1,100 mg Lacto/kg diet (ppm) and 2,200 ppm Lacto in corn-soya bean meal (C-S) diets to layers stimulated appetite, improved egg production (in Experiment 1 only), egg mass, egg weight, egg size, internal egg quality and fat, nitrogen, calcium and phosphorus retentions (P < .05). Production performances were not different between the layers fed the 1,100 ppm diet and those fed the 2,200 ppm Lacto diet. Supplementing Lacto diets with 1 and 3% fat reduced feed consumption, provided better feed conversion, egg production, egg masses, egg size, body weight gains, and nitrogen, calcium and phosphorus retentions. Feeding 1,100 ppm Lacto barley-corn-soya bean (B-C-S) layer diets improved body weight gains and the retentions of fat, phosphorus and manganese and increased the rate of passage of digesta (P < .05). Feeding Lacto C-S and Lacto B-C-S layer diets increased cellularity of Peyer's patches in the ileums of the layers which may stimulate the mucosal immune system. No changes in length and weight of the intestine were observed. Daily feed consumption and body weight gains were improved when pullets were fed 1,100 ppm Lacto from 7 to 19 wk of age (WOA). When these pullets were continued on the Lacto feed during the laying period (20 to 59 WOA), increased feed consumption, egg size, nitrogen and calcium retentions, increased cellularity of Peyer's patches, decreased length and weight of intestine were observed (P < .05). Presence of phytase activity was higher in condensed cane molasses solubles (CCMS)- Lactobacillus premix than the carrier (CCMS). Feeding the CCMS-Lacto diets to layers decreased the pH of the GI tract, increased phytase activities in the GI tract and intestinal tissues and improved shell thickness and phosphorus retention (P < .05). The production performance of layers fed .45% and .25% available phosphorus (AP) diets were not different except for body weight gain. Phosphorus retention was better for layers fed diets containing .25% AP with CCMS-Lacto than the .45% AP control diet. According to these studies, feeding Lacto to pullets and layers improved their performance and the retention of nutrients such as calcium, phosphorus and nitrogen which subsequently reduced the cost of feeding. / Graduation date: 1994

The high quality feedstuffs which are used in poultry feeds are costly and could be used directly for human food. There is less competition for fibrous feedstuffs which are less digestible by humans and other nonruminants. Feedstuffs containing crude and refined dietary fiber were examined for their effects on performance, carcass composition, crude fiber digestibility and anatomical changes of the digestive tract in growing chickens, ducklings, turkey poults and goslings. Crude fiber (CF) from dehydrated alfalfa (DA) fed to broiler chicks at 8.3 to 15% of the ration resulted in significantly reduced body weight (BW), feed consumption (FC) and feed conversion (EF). Refined fiber (RF, Cellulose) at 5 to 20% of the diet of broiler chicks resulted in significantly reduced BW and EF, while FC increased. Bacterial and enzymatic preparations added to broiler chick diets containing up to 20% RF resulted in no significant differences in BW or EF within each RF level. However, FC did not increase as RF increased. RF fed to 4 commercial broiler strain crosses resulted in no significant differences in BW, FC or EF at each level of RF. Percent carcass fat decreased in one strain and increased in all others as RF increased. Dehydrated Kentucky Bluegrass (KBG) or DA based diets fed to goslings resulted in no significant effects on mean BW. DA or KBG at 40% of the diet resulted in significantly increased FC and EF. EF of pelleted diets was better than mash diets. Mean ADF digestibility and mean carcass yields increased as DA or KBG increased in the diet. Microbial preparations (Lactobacillus sp.) fed to goslings in KBG based diets resulted in better gains and a significant improvement in EF. The addition of grit (2%) to control, DA or rye grass roughage diets resulted m no significant differences among the dietary treatments. Digestibility of ADF in chicks, poults and goslings fed diets containing 6% CF (from oat hulls, OH) increased with the level of CF. Ducklings digested no measurable amount of ADF from OH. Mean BW of chicks and ducklings fed the 6% CF diets were less, poults were unaffected, and goslings were more than those fed the control diet (C). Carcass fat pad weights in broilers were reduced, while gizzard weights increased in all species as CF increased. Ceca lengths within species did not vary; small intestines lengths decreased in chicks, ducklings, and poults, but increased in goslings as the level of CF increased in the diet. / Graduation date: 1992

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A series of experiments were carved out to study the effect of dietary enzyme inclusion or flaxseed processing on feeding value of flaxseed for broilers. The feed enzymes tested containing xylanase activities failed to produce any positive performance response when used in a 10% flaxseed diet with manufacturer recommended dosage for broilers (D 1 to 21). / Autoclaving of flaxseed at 16.5 kg/cm2 and 120°C for 15 min slightly improved the performance of young broilers fed a 10% flaxseed diet. This improvement was not observed at lower temperature and shorter period of autoclaving, but was magnified at higher flaxseed level. Autoclaving, microwave roasting, pelleting significantly (P < 0.05) reduced HCN content in flaxseed. The greatest HCN reduction was observed with repeated pelleting (54.9%) and microwave roasting (83.2%), from its 377 mg/kg of raw flaxseed. / When tested with roosters, flaxseed processing effectively increased ME values, dry matter, and ether extract utilization. The raw flaxseed TME and TMEn of 3343 and 3225 kcal/kg, respectively, was significantly (P < 0.01) increased by repeated pelleting (44%) and microwave roasting (32%). It was the result of significant improvement (P < 0.05) of EE utilization by the relevant processing. These improvements had a similar effect on total FA and linolenic acid utilization. / The processing method and flaxseed level had a very significant effect on deposition of total T-3 FAs in breast and thigh meat (P < 0.001) of 40 days old broilers. The highest level of T-3 FAs in muscle lipids of 23.04% and 26.46% for breast and thigh, respectively, was achieved with the highest flaxseed level (14% in days 1 to 21 days, and 17% in days 22--40) and pellet-then-mash processing, which lead to low T-6/T-3 ratios of 0.81 and 0.80 in breast and thigh muscle lipid, respectively. The proper flaxseed processing allowed more flaxseed (up to 12%) to be included in broiler diets without obvious growth depression, while achieving the higher desired T-3 FAs deposition in meat.