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).

在孵化过程中，温度是影响孵化率和雏鸡质量的主要环境条件。孵化第一周后的高温对孵化的影响已得到广泛研究。然而，在孵化的早期阶段知之甚少。本研究旨在研究提高蛋壳温度 ( EST) 的影响) 在孵化 (E) 的前 6 个胚胎 d 期间对孵化率、孵化时间和第一周肉鸡性能的影响。总共 1,680 个孵化蛋被随机分为 4 个处理组，如下所示：对照（37.8°C）、高 EST（38.6°C）从 E0 到 E3、E3 到 E6 和 E0 到 E6。从 E6 开始，所有组的 EST 保持在 37.8°C。与从 E3 到 E3（高 E0-E3）保持在控制温度（37.8°C EST）和 38.6°C EST（E0 至 E3）的鸡蛋相比，鸡蛋的受精孵化率明显更好。 E6（HighE3-E6）和E0到孵化的E6（HighE0-E6）（P <0.05），由于早期胚胎死亡率下降（P< 0.05)。所有处理的平均孵化时间不同，HighE0-E6 的孵化时间最早，其次是 HighE0-E3、HighE3-E6 和 Control 组（P < 0.01）。在孵化的前 6 天，高 EST (38.6°C) 不会显着影响无卵黄体重 ( YFBM ) 和残留卵黄囊 ( RYS ) 重量。在 7 天龄时，发现 HighE0-E3 组和 Control 组的 BW 高于其他 2 组（P < 0.05）。7 d 处理间的饲料消耗（FC）、饲料转化率（FCR）或死亡率均无显着差异（P> 0.05）。这些结果表明，与对照条件相比，鸡蛋从 E0 到 E6 或从 E3 到 E6 的 EST 暴露于 38.6°C EST 缩短了孵化时间，但降低了可育孵化率和​​第一周体重（P < 0.05）。然而，与对照温度相比，孵化前3天EST增加对孵化率、二级雏鸡百分比和第一周肉鸡生产性能没有影响（P > 0.05），但雏鸡孵化更早（P < 0.05）。