Guangdong Provincial Key Laboratory of Animal Nutrition Control, South China Agricultural University, Guangzhou, Guangdong, 510642, China; National Engineering Research Center for Breeding Swine Industry, College of Animal Science, South China Agricultural University, Guangzhou, Guangdong, 510642, China.
Guangdong Provincial Key Laboratory of Animal Nutrition Control, South China Agricultural University, Guangzhou, Guangdong, 510642, China; National Engineering Research Center for Breeding Swine Industry, College of Animal Science, South China Agricultural University, Guangzhou, Guangdong, 510642, China.
J Therm Biol. 2024 Aug;124:103959. doi: 10.1016/j.jtherbio.2024.103959. Epub 2024 Aug 17.
Heat stress is the most critical factor affecting animal feeding in summer. This experiment was conducted to investigate the effects of heat stress on the feeding preference of yellow-feathered broilers and its possible mechanism. As a result, the preference of yellow-feathered broilers for Tenebrio molitor was significantly decreased, and the fear response and serum corticosterone of broilers were significantly increased when the ambient temperatures are 35 °C (P < 0.05). In the central nervous system, consistent with the change in feeding preference, decreased dopamine in the nucleus accumbens (NAc) and increased mRNA levels of MAO-B in the ventral tegmental area (VTA) and NAc were found in yellow-feathered broilers (P < 0.05). In addition, we found significantly increased mRNA levels of corticotropin-releasing hormone receptor 1, corticotropin-releasing hormone receptor 2 and glucocorticoid receptor in the VTA and NAc of female broilers (P < 0.05). However, no similar change was found in male broilers. On the other hand, the serum levels of insulin and glucagon-like peptide-1 were increased only in male broilers (P < 0.05). Accordingly, the mRNA levels of insulin receptor and glucagon-like peptide-1 receptor in the VTA and the phosphorylation of mTOR and PI3K were increased only in male broilers (P < 0.05). In summary, the preference of yellow-feathered broilers for Tenebrio molitor feed decreased under heat stress conditions, and hedonic feeding behavior was significantly inhibited. However, the mechanism by which heat stress affects hedonic feeding behavior may contain gender differences. The insulin signaling pathway may participate in the regulation of heat stress on the male broiler reward system, while stress hormone-related receptors in the midbrain may play an important role in the effect of heat stress on the reward system of female broilers.
热应激是影响夏季动物采食量的最关键因素。本试验旨在研究热应激对黄羽肉鸡采食偏好的影响及其可能的机制。结果表明，当环境温度为 35°C 时，黄羽肉鸡对黄粉虫的偏好显著降低，且肉鸡的恐惧反应和血清皮质酮显著升高（P<0.05）。在中枢神经系统中，与采食偏好的变化一致，黄羽肉鸡伏隔核（NAc）中的多巴胺减少，腹侧被盖区（VTA）和 NAc 中的 MAO-B mRNA 水平升高（P<0.05）。此外，我们发现雌性肉鸡 VTA 和 NAc 中的促肾上腺皮质激素释放激素受体 1、促肾上腺皮质激素释放激素受体 2 和糖皮质激素受体的 mRNA 水平显著升高（P<0.05）。然而，在雄性肉鸡中未发现类似变化。另一方面，仅在雄性肉鸡中血清胰岛素和胰高血糖素样肽-1 水平升高（P<0.05）。因此，仅在雄性肉鸡中 VTA 中的胰岛素受体和胰高血糖素样肽-1 受体的 mRNA 水平以及 mTOR 和 PI3K 的磷酸化增加（P<0.05）。综上所述，黄羽肉鸡在热应激条件下对黄粉虫饲料的偏好降低，享乐性采食行为受到显著抑制。然而，热应激影响享乐性采食行为的机制可能存在性别差异。胰岛素信号通路可能参与了热应激对雄性肉鸡奖赏系统的调节，而中脑内与应激激素相关的受体可能在热应激对雌性肉鸡奖赏系统的影响中发挥重要作用。
