Delayed post-hatch feeding affects the performance and immunocompetence differently in male and female broiler chickens

The effect of post-hatch (PH) feed deprival for 6, 12, 24 and 36 h was studied in male and female broiler chickens. At 21 d, lower body weight (BW) was recorded in 36 h feed-deprived (FD) birds; however, at 42 d PH, only 36 h FD female birds had lower BW compared to control and other FD birds. Feed intake during 0-21 d PH was lower in 36 h FD birds, but feed conversion ratio did not differ between control and FD birds. The H:L ratio significantly increased in 12-36 h FD male birds and 24-36 h FD females. The humoral immune response was similar in FD and control birds, but the cellular immune response was higher in 12 and 24 h FD female birds. At 36 h the expression of interleukin 6 (IL-6), toll-like receptor-2 (TLR-2) and tumour necrosis factor-a-gene was down-regulated in male birds only. However, the expression of IL-6 and TLR-2 was up-regulated in 12-36 h FD female birds at 7 and 14 d PH. It may be concluded that PH feed deprival for the first 24 h did not affect growth performance but improved immune response in slow-growing broiler females.