Center of Excellence for Poultry Science, University of Arkansas System Division of Agriculture, Fayetteville, AR 72701, USA.
Adisseo France S.A.S., Center of Expertise in Research and Nutrition, 03600 Malicorne, France.
Poult Sci. 2023 Nov;102(11):103048. doi: 10.1016/j.psj.2023.103048. Epub 2023 Aug 22.
This experiment determined the effects of different HS models and pair-feeding (PF) on nutrient digestibility and markers of stress, inflammation, and metabolism in broilers. Birds (720 total) were allocated into 12 environmentally controlled chambers and reared under thermoneutral conditions until 20 d. Until 41 d birds were exposed to 4 treatments, including: thermoneutral at 24°C (TN-al), daily cyclic HS (12 h at 24 and 12 h at 35°C; cyHS), constant HS at 35°C (coHS), and PF birds maintained at 24°C and fed to equalize FI with coHS birds (TN-coPF). At d 41, ileal digesta were collected to determine nutrient apparent ileal digestibility (AID). Blood, liver, and breast tissues were collected from 8 birds per treatment to determine the mRNA expression of stress, inflammation, and metabolism markers. An additional 8 TN-al birds were sampled after acute HS exposure at 35°C for 4 h (aHS), and 8 cyHS birds were sampled either right before or 4 h after HS initiation. Data were analyzed by 1-way ANOVA and means were separated using Tukey's HSD test. Compared with TN-al birds, AID of nitrogen and ether extract were reduced in coHS birds, and both cyHS and coHS reduced (P < 0.05) AID of total essential amino acids. TNFα and SOD2 expression were increased (P < 0.05) under aHS, coHS, and TN-coPF conditions. IL6 and HSP70 were increased (P < 0.05) under coHS and aHS, respectively. Expression of lipogenic enzymes ACCα and FASN were reduced by coHS and TN-coPF, while coHS increased the lipolytic enzyme ATGL (P < 0.05). IGF1 was lowered in coHS birds, and p70S6K and MyoG were reduced under coHS and TN-coPF (P < 0.05). Interestingly, MuRF1 and MAFbx were increased (P < 0.05) under coHS only. Overall, these results indicate that coHS has a greater impact on nutrient digestibility and metabolism than aHS and cyHS. Interestingly, increased protein degradation during HS appears to be mostly driven by HS per se and not the reduced FI.
本实验旨在确定不同高温模型和强制给料（PF）对肉鸡养分消化率以及应激、炎症和代谢标志物的影响。将 720 只鸡分配到 12 个环境控制室内，在热中性条件下饲养至 20 日龄。在 41 日龄前，鸡只接受 4 种处理，包括：24°C 的热中性温度（TN-al）、每日循环高温（12 小时 24°C 和 12 小时 35°C；cyHS）、35°C 的持续高温（coHS）和 PF 鸡只维持在 24°C 并根据 coHS 鸡只的采食量进行强制给料（TN-coPF）。在第 41 天，收集回肠食糜以确定养分回肠表观消化率（AID）。每个处理组采集 8 只鸡的血液、肝脏和胸肌组织，以确定应激、炎症和代谢标志物的 mRNA 表达情况。另外，在 35°C 急性高温暴露 4 小时后（aHS），对 8 只 TN-al 鸡进行采样，在高温开始前或 4 小时后对 8 只 cyHS 鸡进行采样。采用单因素方差分析进行数据分析，采用 Tukey 的 HSD 检验进行均值分离。与 TN-al 鸡相比，coHS 鸡的氮和乙醚提取物的 AID 降低，cyHS 和 coHS 降低（P<0.05）了所有必需氨基酸的 AID。aHS、coHS 和 TN-coPF 条件下 TNFα 和 SOD2 的表达增加（P<0.05）。coHS 和 aHS 条件下 IL6 和 HSP70 的表达增加（P<0.05）。coHS 和 TN-coPF 降低了脂肪生成酶 ACCα 和 FASN 的表达，而 coHS 增加了脂肪酶 ATGL（P<0.05）。coHS 鸡的 IGF1 降低，coHS 和 TN-coPF 降低了 p70S6K 和 MyoG（P<0.05）。有趣的是，只有 coHS 鸡的 MuRF1 和 MAFbx 增加（P<0.05）。总的来说，这些结果表明，coHS 对养分消化率和代谢的影响大于 aHS 和 cyHS。有趣的是，高温期间蛋白质降解的增加似乎主要是由高温本身引起的，而不是采食量的减少。
