The present study evaluated whether broiler femoral and tibiotarsal characteristics (as assessed at slaughter age) could be improved if birds were reared under their preferred temperature and whether continuous high or low incubation temperature during the fetal period improves bone characteristics of broilers reared under heat stress or thermal preference. Broiler breeder eggs were incubated from day 13 until hatching under cold (36 °C), control (37.5 °C), or hot (39 °C) temperatures. Under these conditions, the eggshell temperatures were 37.4 ± 0.1°C, 37.8 ± 0.15°C, and 38.8 ± 0.3°C, respectively. Then, broiler chicks were reared under control, preferred (determined previously in thermal preference test), or high temperatures. At day 42 of age, the broilers were weighed and euthanized, and femora and tibiotarsi collected to measure weight, length, diaphysis perimeter, breaking strength, maximum flexion, rigidity, ash, phosphorus, and calcium. Rearing under the preferred temperature did not affect broiler body weight or femoral and tibiotarsal characteristics (P > 0.05). In contrast, high rearing temperature, decreased the body weight, mineral contents of both bones, femoral breaking strength, and tibiotarsal rigidity (P < 0.05). Regarding incubation temperature effects, egg exposure to cold and hot temperatures during the fetal period minimized or avoided a few effects of high rearing temperature, such as those on femoral and tibiotarsal morphological characteristics, mineral composition, and mechanical properties at slaughter age (P < 0.05), but not all. In conclusion, rearing under the preferred broiler temperature did not improve the bone characteristics, and the negative effects of high rearing temperature on bone development were minimized but not completely prevented by high or low temperature incubation during the fetal period.

中文翻译：

---

在胎儿发育过程中改变孵化温度和首选饲养温度都不会改善肉鸡的腿骨特征

本研究评估了肉鸡的股骨和胫骨特征（在屠宰年龄时评估）如果在其首选温度下饲养，是否可以改善肉鸡的股骨和胫骨特征，以及在胎儿期持续高或低的孵化温度是否会改善在热应激下饲养的肉鸡的骨骼特征或热偏好。肉鸡种蛋从第 13 天开始孵化，直到在冷 (36 °C)、对照 (37.5 °C) 或热 (39 °C) 温度下孵化。在这些条件下，蛋壳温度分别为 37.4±0.1°C、37.8±0.15°C 和 38.8±0.3°C。然后，在控制、优选（先前在热偏好测试中确定）或高温下饲养肉鸡。在 42 天龄时，对肉鸡称重并实施安乐死，收集股骨和胫骨以测量体重，长度、骨干周长、断裂强度、最大屈曲度、刚度、灰分、磷和钙。在优选温度下饲养不影响肉鸡体重或股骨和胫骨特征（P > 0.05）。相比之下，高饲养温度降低了体重、两块骨头的矿物质含量、股骨断裂强度和胫骨刚度（P < 0.05）。关于孵化温度的影响，在胎儿期暴露于冷和热的温度可以最大限度地减少或避免一些高饲养温度的影响，例如对股骨和胫骨形态特征、矿物质成分和屠宰年龄机械性能的影响（P < 0.05 ）， 但不是所有的。总之，在优选的肉鸡温度下饲养并没有改善骨骼特性，