The Effect of Stocking Density and Strain on the Performance and Physiological Adaptive Responses in Broiler Chickens

The aim of this study was to determine the effects of stocking density and strain on the performance and physiological adaptive responses including the plasma corticosterone content and the level of mRNA expression of pro- inflammatory cytokines and antioxidant enzymes in broiler chicks. A total of 300 birds of two strains (150 Ross strain vs. 150 Cobb strain) aged 3-d old were allotted into two stocking densities (standard stocking density, 0.046 m 2 /bird vs. high stocking density, 0.023 m 2 /bird) in battery cages by 2×2 factorial designs with ten replicates until 35 d of age. There was no significant strain effect on body weight, feed intakes and feed to gain ratio and the relative organ weights. However body weight, feed intakes and relative organ weight were found to be significantly (P