Bhatia S K, Pradhan K, Singh R
J Dairy Sci. 1980 Jul;63(7):1104-8. doi: 10.3168/jds.S0022-0302(80)83053-0.
Adult male fistulated crossbred cattle and buffalo, four each, were on rations with rations of nonprotein nitrogen to carbohydrates of 1:45, 1:37.5, and 1:30 and a control of no urea in a 4 x 4 Latin square switchover design. The influence of various test diets on enzymes assimilating ruminal ammonia was elucidated to find an optimum ratio of nonprotein nitrogen to soluble carbohydrates for efficient utilization of dietary nitrogen. Inclusion of urea in graded amounts in the ration induced activities of amino-stransferases. Specific activities of trans-aminases were higher in cattle and buffalo for rations with ratios of 1:45 and 1:30 compared to control and 1:37.5 (nonprotein nitrogen to carbohydrate ratio). This indicates a better adaptation of rumen microbes on two former rations which did not differ in augmentation of enzyme activities. Peak enzyme activity of cattle and buffalo at 2 h postfeeding did not differ for microbial enzymes. The ration with narrowest nonprotein nitrogen and carbohydrate ratio (1:30) may be optimum for microbial synthesis of amino acid. It will be worthwhile to study whether a still narrower ratio can make feeding of ruminants more economical.
成年雄性瘘管杂交牛和水牛各4头，采用4×4拉丁方转换设计，分别给予非蛋白氮与碳水化合物比例为1:45、1:37.5和1:30的日粮，并设不添加尿素的对照日粮。研究了不同试验日粮对瘤胃氨同化酶的影响，以确定非蛋白氮与可溶性碳水化合物的最佳比例，以便有效利用日粮氮。日粮中按梯度添加尿素可诱导氨基转移酶的活性。与对照日粮和非蛋白氮与碳水化合物比例为1:37.5的日粮相比，非蛋白氮与碳水化合物比例为1:45和1:30的日粮在牛和水牛中的转氨酶比活性更高。这表明瘤胃微生物对前两种日粮的适应性更好，这两种日粮在酶活性增强方面没有差异。采食后2小时，牛和水牛的微生物酶峰值酶活性没有差异。非蛋白氮与碳水化合物比例最窄（1:30）的日粮可能最适合微生物合成氨基酸。研究更窄的比例是否能使反刍动物饲养更经济将是值得的。
