Effect of genotype and stocking density on broiler performance during two subtropical seasons.

Ross 308 and Cobb Avian48 broilers were raised at stocking densities of 30, 40, and 50 kg BW/m(2) during 49-day production period in winter and summer. The effect of season, genotype, and stocking density on growth performance and carcass characteristics was investigated. Ross 308 consumed more feed, gained more body weight, and was heavier than Cobb at slaughter age. Chickens raised in winter consumed more feed, gained more body weight and were heavier at slaughter age but had a higher mortality rate than those raised in summer. Broilers raised at the stocking density of 30 kg BW/m(2) gained more body weight and were heavier at 49 days than those raised at 40 and 50 kg BW/m(2). There was a progressive reduction in feed intake with increasing stocking density but neither season, genotype nor stocking density influenced feed conversion ratio. There was a genotype effect on the percentage gizzard weight, while stocking density influenced the percentage weights of carcass, breast, gizzard, heart and abdominal fat. There were genotype × stocking density interaction effects on feed consumption during the grower and finisher stages as well as the relative weights of breast, gizzard and heart. It is suggested that for profitable broiler production in the tropics and subtropics Ross 308 reared at stocking density of 30 kg BW/m(2) preferably in winter be considered.