反刍动物瘤胃氮代谢研究进展

瘤胃内氮代谢过程主要包括蛋白质降解和微生物蛋白质合成。蛋白质在瘤胃内的降解由瘤胃微生物来完成,蛋白质的物理和化学特性、瘤胃及其内容物的特性均影响蛋白质降解。碳水化合物和蛋白质是限制瘤胃微生物生长的主要因素。瘤胃微生物蛋白质合成效率能准确地表示微生物对可利用能量的利用率,而瘤胃氮利用率能准确地表示微生物捕获可利用氮的效率,两者互补,可全面显示微生物对养分的利用效率。细菌细胞对氮的分配随发酵速度而变化,故以微生物氨基酸氮的质量作为瘤胃微生物蛋白质合成效率或氮利用率的衡量标准可能较微生物氮更准确。

Research Advance on Nitrogen Metabolism in the Rumen of Ruminants

Nitrogen metabolism in the rumen can be divided into 2 distinct events:protein degradation and microbial protein synthesis.Protein degradation in the rumen is the result of microbial activity and affects by physical and chemical characteristics of protein and the characteristics of rumen and ruminal digesta.The most limiting factors in microbial growth in the rumen are carbohydrate and protein.Efficiency of microbial protein synthesis in the rumen is a valid indicator of how microbes use available energy.And efficiency of nitrogen utilization in the rumen effectively describes efficiency of available nitrogen captured by microbes.They appear to be complementary measurements of efficiency of microbial nutrient use.Because the distribution of nitrogen within bacterial cells changes with rate of fermentation,using amino acid nitrogen rather than bacterial nitrogen in the numerator would be a more precise expression of efficiency of microbial protein synthesis or nitrogen utilization.