Effect of high eggshell temperature during the early period of incubation on hatchability, hatch time, residual yolk, and first-week broiler performance1

SUMMARY: During incubation, temperature is the main environmental condition affecting the hatchability and chick quality. The effect of high temperature after the first week of incubation to hatching has been widely investigated. However, very little is known during the early period of incubation. This study was conducted to investigate the effect of increased eggshell temperature (EST) during the first 6 embryonic d of incubation (E) on hatchability, hatch time, and first-week broiler performance. A total of 1,680 hatching eggs were divided randomly into 4 treatment groups were as follows: Control (37.8°C), High EST (38.6°C) from E0 to E3, E3 to E6, and E0 to E6. The EST was maintained at 37.8°C from E6 onward in all groups. Fertile hatchability was significantly better in eggs maintained at the control temperature (37.8°C EST through incubation) and at 38.6°C EST from E0 to E3 (High E0-E3) compared to eggs exposed to an EST of 38.6°C from E3 to E6 (HighE3-E6) and E0 to E6 (HighE0-E6) of incubation (P < 0.05) due to decreased early embryonic mortality (P < 0.05). The average hatch time differed among all treatments, with the earliest hatch time for HighE0-E6 followed by the HighE0-E3, HighE3-E6, and Control groups (P < 0.01). Yolk free body mass (YFBM) and residual yolk sac (RYS) weight were not significantly affected by high EST (38.6°C) during the first 6 d of incubation. At 7 d of age, the HighE0-E3 and Control groups were found to have greater BW than the other 2 groups (P < 0.05). No significant difference was found for feed consumption (FC), feed conversion ratio (FCR), or mortality among the treatments for 7 d (P > 0.05). These results suggest that compared with the control condition, the exposure of eggs to 38.6°C EST from E0 to E6 or from E3 to E6 of incubation shortened the hatch time but decreased fertile hatchability and the first week BW (P < 0.05). However, compared with the control temperature, increased EST during the first 3 d of incubation did not impact hatchability, percentage of second-grade chicks and first-week broiler performance (P > 0.05), but chicks hatched earlier (P < 0.05).