College of Animal Science and Technology, Key Laboratory of Animal Origin Food Production and Safety Guarantee of Jiangsu Province, Jiangsu Collaborative Innovation Center of Meat Production and Processing, Quality and Safety Control, Joint International Research Laboratory of Animal Health and Food Safety, National Experimental Teaching Demonstration Center of Animal Science, Nanjing Agricultural University, Nanjing 210095, PR China.
School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing 210023, PR China.
Poult Sci. 2021 Jan;100(1):215-223. doi: 10.1016/j.psj.2020.09.090. Epub 2020 Oct 10.
Heat stress impairs growth performance and alters body protein and amino acid metabolism. This study was investigated to explore how body protein and amino acid metabolism changed under heat stress (HS) and the stress adaptation mechanism. A total of 144 broilers (28 d old) were divided into 3 treatment groups for 1 wk: HS group (32°C), normal control group (22°C), and pair-feeding group (22°C). We found that HS elevated the feed-to-gain ratio, reduced the ADFI and ADG, decreased breast muscle mass and plasma levels of several amino acids (glycine, lysine, threonine, and tyrosine), and increased serum glutamic oxaloacetic transaminase (GOT) activity and corticosterone (CORT) level and liver GOT and glutamic pyruvic transaminase activities. Heat stress elevated muscle atrophy F-box mRNA expression and reduced mRNA expression of the 70-kD ribosomal protein S6 kinase in the breast muscle of broilers. Broilers in the HS group exhibited striking increases of mRNA expressions of solute carrier family 1 member 1, family 3 member 1, family 7 member 1, and family 7 member-like in the liver and liver gluconeogenesis genes (PCKc, PCKm, PC, and FBP1) in comparison with the other 2 groups. In conclusion, HS increased the circulating CORT level and subsequently caused muscle protein breakdown to provide amino acid substrates to liver gluconeogenesis responsible for energy supply.
热应激会损害生长性能，并改变机体蛋白质和氨基酸代谢。本研究旨在探讨机体蛋白质和氨基酸代谢在热应激（HS）下如何发生变化，以及应激适应机制。将 144 只 28 日龄肉鸡分为 3 个处理组，每组 48 只，分别在 32°C（HS 组）、22°C（正常对照组）和 22°C 下进行等热量限饲（配对组），持续 1 周。结果发现，HS 增加了料重比，降低了 ADFI 和 ADG，减少了胸肌质量和几种氨基酸（甘氨酸、赖氨酸、苏氨酸和酪氨酸）的血浆水平，增加了血清谷氨酸草酰乙酸转氨酶（GOT）活性和皮质酮（CORT）水平，以及肝脏 GOT 和谷氨酸丙酮酸转氨酶活性。热应激增加了肉鸡胸肌中肌肉萎缩 F -box mRNA 的表达，降低了 70kD 核糖体蛋白 S6 激酶的 mRNA 表达。与其他两组相比，HS 组肉鸡肝脏溶质载体家族 1 成员 1、家族 3 成员 1、家族 7 成员 1 和家族 7 成员样的 mRNA 表达以及肝脏糖异生基因（PCKc、PCKm、PC 和 FBP1）的 mRNA 表达显著增加。总之，HS 增加了循环 CORT 水平，随后导致肌肉蛋白分解，为肝脏糖异生提供氨基酸底物，以提供能量。
