Carcass composition and skeletal muscle distribution in broilers produced under different nutritional regimes-3. Male broilers showing maximum early growth and restricted later growth

1. In this study we investigated feeding methods which would lead to a high hind limb to wing muscle ratio in broilers. One group of male chicks was reared with a layer grower feed (LG, ME 11.92 MJ/kg, CP 170g/kg) from 1 to 80 (LG80d) or 95 (LG95d) days of age. A further group of chicks was reared with a broiler starter feed (BS, ME 13.18 MJ/kg, CP 205g/kg) from 1 to 21 days and then with a pre-layer feed (PL, ME 11.72 MJ/kg, CP 140 g/kg) up to 80 (BSPL80d) or 95 (BSPL95d) days. 2. LG80d (249Og live weight) and BSPL8d (2648g) birds did not attain sufficient body size (3kg) to slaughter at 80 days. LG95d (2979 g) and BSPL95d (3409 g) birds needed 15 extra days to attain a body size similar to conventionally-fed broilers. The rapid early growth induced by feeding the BS diet contributed greatly to increasing the ultimate body size of the broilers. 3. Carcass weight as a percentage of live weight was 83-85% in all broiler groups. Skeletal muscle as a whole accounted for 45-51% of carcass weight and the largest percentage was found in BSPL95d birds which were also the largest birds. 4. Wing muscle represented 21-23% of the total carcass weight. Hind limb muscle accounted for 18-21%, and cervicodorsal muscle, 4.5-4.9% of total carcass weight. The hind limb weight as a percentage of wing muscle weight was similar among the chicken groups at 85-88%, and this is larger than the value of 76% found in previous work (Das et al., 2008b) and in conventionally-fed broilers (Roy et al., 2007). 5. From these results, it seems that the relative size of the hind limb to wing muscle is increased by restricting broiler growth during the pre-slaughter period and that early maximum growth has a positive effect on meat production by increasing carcass weight without altering the relative size of hind limb to wing muscle.