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目的：观察热环境对机体蛋白质代谢和蛋白质需要量的影响。方法：７２只成年雄性ＳＤ大鼠随机分为６组：实验第１～５组饲料蛋白质含量为５％～２５％；对照组含量为２０％。实验组热暴露１２ｄ，每天２ｈ。于热暴露前及热暴露第１～３，４～６，７～９和１０～１２天，收集粪、尿，测定氮含量，计算氮平衡；于热暴露前及热暴露后第３，６，９，１２天测定血清清蛋白和总蛋白含量。结果：６组大鼠摄食量及饮水量未见明显变化。热暴露应激期，低蛋白质（５％，１０％）及过高蛋白质（２５％）摄入组尿氮排出明显增多，氮平衡显著下降；而中等量蛋白质（１５％和２０％）摄入组尿氮排出明显降低，氮平衡值下降，但幅度较小。热暴露适应期，中等量和过高蛋白质摄入组尿氮排出量和氮平衡值恢复正常；但低蛋白质摄入组仍维持原样。热暴露期间，过高蛋白质摄入组粪氮排出量较高，其他组未见明显改变。热暴露应激期，低蛋白质摄入组血清清蛋白含量显著下降，而其他各组的血清清蛋白和总蛋白含量变化不显著。在热适应期间，血清清蛋白和总蛋白含量变化不明显。结论：在热暴露期间，动物蛋白质需要量明显增加，以热应激期最高，提示热环境可引起蛋白质分解代谢增加，增加蛋白质需要量
Objective: To observe the impact of thermal environment on protein metabolism and protein requirements. Methods: Seventy-two adult male Sprague-Dawley rats were randomly divided into 6 groups: the feed protein content of the first to fifth groups was 5% -25%; the control group was 20%. Experimental group heat exposure 12d, 2h daily. Before heat exposure and heat exposure 1 ~ 3, 4 ~ 6, 7 ~ 9 and 10 ~ 12 days, collecting feces and urine, measuring nitrogen content, calculating nitrogen balance; before heat exposure and heat exposure after 3,6 Serum albumin and total protein were measured at 9 and 12 days. Results: There was no significant change in food intake and water intake in 6 rats. In the exposure period of heat exposure, the urinary nitrogen excretion increased significantly and the nitrogen balance decreased significantly in the intake of low protein (5%, 10%) and excess protein (25%), while the moderate amount of protein (15% and 20%) Urinary nitrogen excretion was significantly lower, nitrogen balance decreased, but less. During heat exposure adaptation, urinary nitrogen excretion and nitrogen balance returned to normal with moderate and high protein intakes; however, the low protein intake group remained intact. Exposed to high protein intake of fecal nitrogen was higher during heat exposure, with no significant changes in the other groups. During the heat exposure stress period, serum albumin content decreased significantly in the low protein intake group, while serum albumin and total protein content in other groups did not change significantly. During heat adaptation, serum albumin and total protein content did not change significantly. CONCLUSION: During heat exposure, the protein requirements of animals increased significantly, with the highest heat stress period, suggesting that the thermal environment may cause increased protein catabolism and increase the protein requirement