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 12 h post-hatch handling period: control, high and low temperature groups, with average body temperatures of 40.0, 42.6, and 38.1°C, 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 (42.6°C) 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 (40.0°C) and low (38.1°C) 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.

This study investigated the effects of broiler chick hatching time on the percentage of the yolk sac and subsequent broiler live performance. Broiler hatching eggs were obtained from a commercial flock at 55 wk of age and were stored for 2 d at 18°C and 75% relative humidity (RH) prior to incubation. Chicks were identified as hatching Early (471-477 h), Middle (480-486 h), and Late (494-510 h). All chicks were removed from the trays at 510 h of incubation. Body weight (BW) and yolk weight (YW) were determined at emergence from the shell (initial hatch time) and at placement on feed. Chicks were permanently identified by hatch time with neck tags, feather sexed, weighed, and introduced to feed and water in litter floor pens.

The effects of heating of eggs during storage, broiler breeder age, and length of egg storage on hatchability of fertile eggs were examined in this study. Eggs were collected from Ross 344 male × Ross 308 broiler breeders on paper flats, held overnight (1 d) at 18°C and 75% RH, and then transferred to plastic trays. In experiment 1, eggs were obtained at 28, 38, and 53 wk of flock age. During a further 10 d of storage, eggs either remained in the storage room (control) or were subjected to a heat treatment regimen of 26°C for 2 h, 37.8°C for 3 h, and 26°C for 2 h in a setter at d 5 of storage. In experiment 2, eggs from a flock at 28 wk of age were heated for 1 d of a 6-d storage period. Eggs from a 29-wk-old flock were either heated at d 1 or 5 of an 11-d storage period in experiment 3. In experiment 4, 27-wk-old flock eggs were heated twice at d 1 and 5 of an 11-d storage period. Control eggs stored for 6 or 11 d were coincubated as appropriate in each experiment. Heating eggs at d 5 of an 11-d storage period increased hatchability in experiment 1. Although no benefit of heating 28-wk-old flock eggs during 6 d of storage in experiment 2 was observed, heating eggs from a 29-wk-old flock at d 1 or 5 of an 11-d storage period increased hatchability in experiment 3. Further, heating eggs from a 27-wk-old flock twice during 11 d of storage increased hatchability in experiment 4. These effects were probably due to the fact that eggs from younger flocks had been reported to have many embryos at a stage of development where the hypoblast had not yet fully developed (less than EG-K12 to EG-K13), such that heating during extended storage advanced these embryos to a more resistant stage.

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