Carcass composition and skeletal muscle distribution in broilers produced under different nutrition regimes-2. Male broilers fed for rapid later growth following severe nutritional restriction during early growth

1. The results of a previous experiment indicated that chicks whose growth was severely restricted through under nutrition, had the larger than normal hind limb muscles relative to wing muscles at 21 days of age (Das et al., 2008). In this study, we investigated whether the large relative size of hind limb muscle was maintained in the broilers when their growth was accelerated after 3 weeks. 2. The chicks at 21 days of age, which were reared with layer grower (LG, ME 11.92 MJ/kg, CP 170 g/kg) or pre-layer (PL, ME 11.72 MJ/kg, CP 140 g/kg) feeds, had their growth accelerated by feeding a broiler finisher (BF, ME 13.47 MJ/kg, CP 180 g/kg) diet and were then killed at 80 days of age (LGBF80d and PLBFSOd groups, respectively). 3. Both broiler groups had attained an adequate body size compared with conventionally-fed chicks at 80 days of age (Nakamura et al., 2004; Roy et al., 2007). PLBFSOd broilers gained more live weight (3298 g) than LGBFSOd (308Sg) broilers. The carcass accounted for 84-85% of live weight and skeletal muscle made up 48% of carcass weight. 4. Total muscle weight as a percentage of carcass weight was 24% for wing muscle, 18% for hind limb muscle and 4.5% for cervicodorsal muscle. The size of the hind limb muscle relative to wing muscle was 75.9-76.5% and this did not differ from the value of 76.5% reported for conventionally-fed broilers (Roy et al, 2007). The high percentage of hind limb compared to wing muscle weight in LG (83.3%) and PL (96.7%) chicks at 21 days of age had returned to normal levels following stimulation of growth with the BF feed from days 22 to 80. 5. These results suggest that wing muscle growth limitation with under nutrition during the first 3 weeks post-hatching did not influence the final size of the muscle at 80 days when a BF diet was fed from days 22 to 80.