Effect of chick body temperature during post-hatch handling on broiler live performance1

The current study investigated the effect of chick body (rectal) temperature during the post-hatch handling period on body weight (BW) loss, yolk sac utilization, organ weights, and broiler live performance. Hatching eggs were obtained from a commercial flock of Ross 308 broiler breeders at 44 wk of age. A total of 384 chicks were separated into 3 groups during the 12h post-hatch handling period: control, high and low temperature groups, with average body temperatures of 40.0, 42.6, and 38.1C, respectively. Residual yolk sac weight was not affected by temperature group, whereas the weights of organs such as the heart, gizzard, proventriculus, and bursa of Fabricius were significantly lower in the high body temperature group than in the control and low body temperature groups. BW was significantly lower at placement in chicks in the high temperature group than in chicks in the control and low body temperature groups due to greater weight loss during the post-hatch handling period (P 0.05). Lower BW was maintained in the chicks in the high body temperature group than in the chicks in the other 2 groups until the end of the experiment at 35 d (P 0.05) because chicks in the high temperature group consumed less feed throughout the experiment (P 0.05). Feed conversion ratio (FCR) and mortality were numerically greater in the high body temperature chicks than in the control group, whereas FCR and the mortality in the low body temperature chicks were intermediate at 35 d. The results of the present study indicate that day-old chicks with high body temperatures (42.6C) exhibited a greater percentage of BW loss due to dehydration and lower organ weights during the 12 h post-hatch handling period, which was followed by significantly poorer broiler performance. There were no significant differences in performance between the chicks in the control (40.0C) and low (38.1C) body temperature groups. In conclusion, day-old chicks are more sensitive to higher body temperatures than to lower temperatures during the post-hatch handling period.