Odle J, Schaefer D M
Br J Nutr. 1987 Jan;57(1):127-38. doi: 10.1079/bjn19870016.
Four rumen-cannulated steers were given barley and maize diets supplemented with graded levels of an ammonium acetate solution. Animals were fed hourly from automatic feeders and water consumption was controlled to achieve steady-state conditions in the rumen. Dacron bags containing rolled barley or ground barley were incubated in the rumen of barley-fed steers, while ground maize and autoclaved maize were incubated in the rumen of maize-fed steers. Fractional degradation rates of dry matter were estimated for each cereal substrate incubated using a single-pol exponential decay model. No differences in degradation rate due to the method of feed processing were detected; however, barley was degraded at a faster rate than maize. Furthermore, the minimum rumen ammonia-nitrogen concentration required to maximize the degradation rate of barley (125 mg/l) was greater than that required to maximize the degradation rate of maize (61 mg/l). These results indicate that the optimal NH3-N concentration required to maximize the rate of grain digestion in the rumen is influenced by the chemical or structural characteristics of the grain.
给四头装有瘤胃瘘管的阉牛喂食添加了不同梯度乙酸铵溶液的大麦和玉米日粮。通过自动喂食器每小时给动物喂食一次，并控制饮水量以实现瘤胃内的稳态条件。将装有碾压大麦或磨碎大麦的涤纶袋在以大麦为食的阉牛瘤胃中进行培养，而将磨碎玉米和经高压灭菌的玉米在以玉米为食的阉牛瘤胃中进行培养。使用单池指数衰减模型估算每种培养的谷物底物的干物质分数降解率。未检测到因饲料加工方法导致的降解率差异；然而，大麦的降解速度比玉米快。此外，使大麦降解率最大化所需的最低瘤胃氨氮浓度（125毫克/升）高于使玉米降解率最大化所需的浓度（61毫克/升）。这些结果表明，瘤胃中谷物消化率最大化所需的最佳氨氮浓度受谷物化学或结构特征的影响。
