The aim of this study was to evaluate the effects of broiler maternal dietary lysine intake on progeny performance. Three experiments were conducted with chicks hatched from Cobb 500 breeders at 38, 48, and 60 weeks of age. Breeder hens received six dietary treatments (T1-T6) from 26 to 60 weeks of age, which allowed an intake of 800, 930, 1070, and 1200 mg lysine/bird/d (T1-T4) respectively. An intake of 800 mg/bird/d at 26 weeks was increased by 25 mg every two weeks to provide 1225 mg lysine/bird/d at 60 weeks (T5). An intake of 1200 mg/bird/d at 26 weeks was reduced by 25 mg every two weeks to supply 775 mg lysine/bird/d at 60 weeks (T6). A total of 320, 401, and 390 chicks were hatched from breeder hens at 38, 48, and 60 weeks of age respectively. Immediately after hatching, 270, 384, and 384 unsexed chicks from breeder hens at 38, 48 and 60 weeks of age respectively, were placed in an environmentally controlled room and randomly allocated (within a treatment) to single-tier cages (80 × 50 cm). Nine chicks from breeders at 38 weeks of age and 8 chicks from breeders at 48 and 60 weeks of age were placed in each pen, keeping chicks from the same treatment group together for 21 d. Chicks were fed ad libitum with a commercial broiler starter crumble for 21 d and water was provided ad libitum throughout the duration of each trial. Feed intakes (FI), body weight gain (BWG) and feed conversion ratio (FCR) were measured weekly. Data were subjected to analysis of variance using a generalized linear model of GenStat 12th edition. Simple linear regression model of GenStat 12th edition was used where appropriate. Significant improvements in offspring feed intake and body weight gain from 7-21 d were observed in chicks hatched from young breeder flocks (38 weeks) with low dietary lysine intakes (800, 930 and 950 mg/bird/d). The effect of maternal dietary lysine intake on offspring performance disappeared with the aging of the breeder flock (60 weeks). It was concluded that lower maternal dietary lysine intakes (800, 930 and 950 mg/bird/d) may improve feed intake and body weight gain from 7-21 d of broiler chicks hatched from younger breeder flocks (38 weeks). / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.

The increased demand for breast meat of broiler chickens has challenged researchers to investigate management techniques that could be used to increase the production of this valuable commodity. Two experiments were conducted in this study; the first investigated the effect of early feeding of newly hatched broilers on breast meat yield (BMY) at market weight, and the second focused on improving BMY of broilers exposed to short daylengths by feeding higher than conventional levels of dietary protein. In the first experiment, of the 528 eggs set in the incubator, half were placed, at day 18, in hatching trays containing a commercial broiler starter feed whilst the others (the held group) were hatched conventionally. Six chicks from both fed and held groups were sampled at nine-hour intervals from the time that the first chicks hatched for a subsequent period of 36 h. After measuring their body weight these chicks were euthanised and dissected in order to measure their breast and yolk weights. Body protein, lipid and water contents were measured on each chick. At day 21, six birds from the fed and held groups were sampled, and body weight, breast weight and body protein content were measured. The yolk sac weight for fed birds was significantly reduced compared to that of held birds (P < 0.001). Both fed and held birds had the same breast weight at hatch, but at day 21 the mean breast weight of the fed birds was significantly heavier than of held birds (P < 0.05). The birds that were removed first from the hatcher had a reduced breast muscle weight compared to those that were removed last. In the second experiment, a total of 3200 day-old broiler chicks were reared in eight light-tight rooms. Four lighting regimens (12L: 12D, 16L: 8D, 20L: 4D and 24L: 0D) were randomised between rooms, with each light treatment being replicated twice. Each room was divided into four pens and 100 chicks in each pen received one of four dietary protein treatments. At day 35, three birds from each pen were sacrificed so that measurements could be made of breast, thigh, drum and wing weight, and carcass chemical composition. Breast weight increased as daylengths increased except in birds that were fed low protein diet (143 g protein/kg feed). High levels of dietary protein increased breast weight in birds on all other daylengths except for those on 12 h which showed a reduced breast muscle weight when dietary protein content was increased. The results of the first trial suggests that breast meat yield could be improved if newly hatched chicks are offered feed immediately after hatch, however the hypothesis that this increment was due to an overall increase in body protein content in the first few days after hatching could not be corroborated. The results further showed that held birds do not withdraw nutrients from breast muscle to maintain growth at hatch, this is because birds that stayed longer in the hatchery without feed showed increased breast muscle weight compared to those that were removed first. The second trial could not identify a suitable feeding programme to overcome the problem of a lower breast muscle weight that results from the use of 12 h of lighting compared to that when long daylengths are used. Highest breast weight was obtained when birds were fed high protein diet at 20 h. More research is required to further investigate the combined effect of early feeding and daylength on breast meat yield in broiler chickens. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.

Fertility of Broiler Breeders (BBs) has been researched over many years with inconclusive findings. Genetic selection and improvements in growth traits have had negative effects on fertility of BB. One explanation is related to overweight birds, resulting in the inability of birds to copulate successfully, with no cloacal contact. The requirements of CP for egg production in BB females have been quantified, but there is less literature on how CP affects fertility in male BBs. The objective of this experiment was to investigate the effects of feeding BB males different dietary CP intakes (10.4, 12.4, 14.2, 17.8, 19.3 and 20.1 g CP/bird/day) on fertility in flocks with natural mating and in birds that were artificially inseminated (AI). Results showed that birds consuming 10.4 and 12.4 g CP/bird/day resulted in weight loss (between 24.9 and 23.6% and 26.5 and 22.4% below target BW) over the 29 weeks of the experimental period in both natural mating and individual pens respectively. Intakes of higher protein content (17.8- 20.1 g CP/bird/day) however resulted in BW gain over the experimental period. Hatch percentage across all CP intakes throughout the duration of the study was found to be high, ranging between 75- 100 and 80-95 % in AI and naturally mated birds respectively, and not affected by CP intakes. Similar results for predicted fertility using the methods published by Brillard & Antoine (1990) and Wishart (1997) were found; however Brillard & Antoine (1990) is more lenient requiring less outer perivitelline layer (OPVL) sperm/mm2 to pronounce an egg fertile. Improved fertility predictions could have been made by using examination of inner perivitelline layer (IVPL). There was a tendency for a superior response in predicted fertility from birds with a protein intake of 14.2 g CP/bird/day. This intake also least affected the BW of the male birds and thus 14.2 g CP/bird/day can be recommended for optimal BB male performance. / Thesis (M.Sc.Agric.)-University of KwaZulu-Natal, Pietermaritzburg, 2010.

The objective of this study was to compare the nutrient status of full scavenging and semi-scavenging village chicken production systems. The semi-scavenging chickens were given broiler finisher mash between 14-24 weeks of age, whilst the full scavenging relied on natural foraging. The study also sought to compare the quality of meat from chickens from the two systems. After slaughtering the chickens, the crop contents were physically separated and analysed for chemical composition. Meat pH and colour were measured on the breast muscle of individual carcasses and a consumer sensory evaluation was also done on the breast muscle. The mean crop content weights per day were significantly higher in full scavenging chickens (±16.7g/day biomass) than in semi-scavenging chickens (±9.14g/day). Dry matter, calcium, and phosphorus levels were higher in the crop contents of the full than in the semi-scavenging chickens but crude protein, crude fibre and metabolisable energy were higher in the latter system. Semi-scavenging (1.3 ± 0.05kg) carcasses were heavier (P<0.05) than full scavenging ones (1.0 ± 0.06kg). The ultimate pH (24h) (pHu) of meat from full scavenging chickens (6.0 ± 0.03) was higher (P<0.05) than that of meat from the semi-scavenging chickens (5.7 ± 0.04). Meat from the full scavenging chickens had higher L* values (60 ± 1.2) than meat from the semi-scavenging chickens (47 ± 0.8). The a* value of meat of full scavenging chickens was significantly (P<0.05) less (4 ± 0.4) than that of meat from semi-scavenging chickens (15 ± 1.3). There was a significant positive (0.60) correlation between pHu and L* of meat from village chickens across rearing systems. The semi-scavenging system meat had better sensory attributes than the meat from the full scavenging system. Female consumers scored the typical flavour of village chicken meat across rearing systems higher (P< 0.05) than male consumers. The Shona consumers scored the meat higher (P< 0.05) than the Xhosa, Zulu, Ndebele and other tribes for initial juiciness, first bite impression and muscle fibre and tenderness of the chicken across rearing systems. Consumers scored of the meat from the semi-scavenging system higher (P<0.05) on initial juiciness (4.3 ± 0.20), first bite impression (4.2 ± 0.197), muscle fibre tenderness (4.5 ± 0.217) than meat from the full scavenging chickens. There were positive correlations (0.46) between aroma intensity and overall flavour intensity across both rearing systems. The semi-scavenging system produced better carcass characteristics, lighter (L*) meat and more consumer acceptable meat than full scavenging chickens. Therefore the full scavenging rearing system had better nutrient composition in its scavenging feed resource base, although the semi-scavenging systems produced chickens with better carcass, meat pH, colour and sensory characteristics than the full scavenging chickens.