日粮氨基酸对犊牛生长和健康影响的研究进展

犊牛在断奶前免疫系统发育不成熟，体质敏感，而在断奶后生长发育迅速。这两个阶段的犊牛都需要提供含有优质蛋白质的日粮以保证其生长发育。结合中国蛋白质资源紧缺的现状，做好犊牛阶段的氨基酸营养在促进犊牛健康生长和提高蛋白质利用率上都具有重要作用。此外，氨基酸在提高犊牛免疫力方面有不可替代的作用，近年来的研究还发现，氨基酸对犊牛消化道易感细菌和病毒有特殊的抑制功能。针对犊牛生长速度快、免疫功能不完善、死亡率高、断奶前后生理结构和营养需要变化迅速的生理特点，作者重点介绍了单一氨基酸不同水平及多种氨基酸不同比例对犊牛断奶前后生长性能的影响，并从氨基酸提高犊牛自身免疫力和抑制微生物繁殖两方面来阐述氨基酸对犊牛健康的影响机制，以期为推进氨基酸在犊牛生产中的应用提供理论依据。

Current Situation for Effect of Dietary Amino Acids on Growth Performance and Immune Function in Calves

The immune system of calves is immature and sensitive before weaning.However,the calves can grow rapidly after weaning.In both stages,it is necessary to provide a diet containing high quality protein to ensure the growth of calves.Considering the current situation of protein shortage in China,optimizing amino acids supply to calves is important for improving health status and utilization rate of protein in the calf stage.In addition,amino acid can play an important role in improvement of immune function in the calves.Recently,some studies found that amino acids would have some special effects on susceptible bacteria and virus in digestive tract of calves.According to the physiological characteristics of calves,such as the rapid growth,imperfect immune function,high mortality and rapid changes in physiological structure and nutritional requirements before and after weaning,the authors reviewed the effects of different levels of single amino acid and different proportions of multiple amino acids on the growth performance of calves before and after weaning.The mechanisms about the effects of amino acids on the health of calves from the aspects of improvement of autoimmunity of calves and inhibiting microbial reproduction was summarized also.The paper was to provide theoretical basis for promoting the application of amino acid in calf production.