College of Life Science, Northeast Agricultural University, Harbin 150030, China.
College of Animal Science and Technology, Northeast Agricultural University, Harbin 150030, China.
Poult Sci. 2022 Oct;101(10):102073. doi: 10.1016/j.psj.2022.102073. Epub 2022 Jul 27.
This study aims to assess the effect of intermittent and mild cold stimulation (IMCS) on thymus function and the ability of 1-day-old male Ross 308 broilers to withstand cold. Four hundred broilers were reared under normal and mild cold temperatures at 3°C below the normal feeding temperature and were subjected to acute cold stress (ACS) at 10°C on d 50 at 7 am for 6 h, 12 h, and 24 h. We determined the expression levels of toll-like receptors (TLRs), cytokines and avian β-defencins (AvBDs), encoding genes in thymus of broilers at 22, 36, 43, and 50 d of age, and the serum ACTH and cortisol (CORT) levels at 50 d of age. At D22 and D36, the mRNA expression levels of TLRs and AvBDs genes in CS groups were generally significantly decreased (P < 0.05). The lowest expression levels were found in birds submitted to intermittent and mild cold stimulation training for 5 h (CS5 group) on d 22 and 36 of development (P < 0.05). At D43 and D49 after IMCS, mRNA expression levels of most TLRs and AvBDs were significantly lower than those in CC group (P < 0.05), and that mRNA expression levels of all TLRs and most AvBDs in CS5 group had the same change trend with age as those in CC group (P > 0.05). At D22 and D36, mRNA expression levels of different cytokines in each CS groups were different (P < 0.05). mRNA expression levels of IL-2, IL-4, IL-6, IL-8, IL-17, and IFN-α all reached the highest values in the CS5 group at D36 (P < 0.05). The levels of ACTH and CORT in all IMCS-treated birds changed in varying degrees after ACS, but there was no significant change in CS5 group (P > 0.05). Collectively, different cold stimulation schemes could modulate thymus immune function of broilers by maintaining homeostasis and enhancing cold resistance. In particular, the optimal cold adaptation scheme was at 3°C below the conventional feeding temperature for 5 h.
本研究旨在评估间歇性温和冷刺激（IMCS）对胸腺功能的影响，以及 1 日龄雄性罗斯 308 肉鸡耐受冷应激的能力。将 400 只肉鸡在正常和温和寒冷温度下饲养，正常饲养温度降低 3°C，在第 50 天上午 7 点进行急性冷应激（ACS），持续 6 小时、12 小时和 24 小时。我们在 22、36、43 和 50 日龄时测定了肉鸡胸腺中 Toll 样受体（TLR）、细胞因子和禽类β-防御素（AvBDs）编码基因的表达水平，以及 50 日龄时的血清促肾上腺皮质激素（ACTH）和皮质醇（CORT）水平。在 CS 组中，TLR 和 AvBDs 基因的 mRNA 表达水平在 D22 和 D36 时通常显著降低（P < 0.05）。在发育的第 22 和 36 天，接受间歇性温和冷刺激训练 5 小时的 CS5 组鸡的表达水平最低（P < 0.05）。在 IMCS 后 D43 和 D49，大多数 TLR 和 AvBDs 的 mRNA 表达水平明显低于 CC 组（P < 0.05），CS5 组的所有 TLR 和大多数 AvBDs 的 mRNA 表达水平随年龄的变化趋势与 CC 组相同（P > 0.05）。在 D22 和 D36 时，每个 CS 组的不同细胞因子的 mRNA 表达水平不同（P < 0.05）。在 D36 时，CS5 组的 IL-2、IL-4、IL-6、IL-8、IL-17 和 IFN-α 的 mRNA 表达水平均达到最高值（P < 0.05）。在 ACS 后，所有接受 IMCS 处理的鸟类的 ACTH 和 CORT 水平均发生不同程度的变化，但 CS5 组无明显变化（P > 0.05）。总之，不同的冷刺激方案通过维持内环境平衡和增强抗冷性来调节肉鸡的胸腺免疫功能。特别是，最佳的冷适应方案是在正常饲养温度降低 3°C 的情况下进行 5 小时。
