Cozzi G, Polan C E
Department of Animal Science, University of Padova, Italy.
J Dairy Sci. 1994 Mar;77(3):825-34. doi: 10.3168/jds.S0022-0302(94)77017-X.
Holstein cows (n = 24, 9 primiparous) were assigned equally to diets based on corn silage and high moisture corn supplemented with soybean meal alone or with either corn gluten meal or dried brewers grains. In diets with two protein sources, the protein quantity from each source was similar. Dietary CP and ADF averaged 16.3 and 18.8%, and undegraded protein as a percentage of CP was 33.6, 41.1, and 41.8% for the respective diets. After parturition, cows were fed the soybean meal diet for a 3-wk covariant period, an experimental diet for 10 wk, the soybean meal diet for 3 wk, and the experimental diet for another 10 wk. Milk production by cows fed those diets averaged 30.9, 31.7, and 34.9 kg/d; protein averaged .90, .94, and 1.02 kg/d; and DMI averaged 16.8, 18.8, and 18.2 kg/d, respectively, for the two 10-wk periods. No dietary differences occurred for 3.5% FCM, estimated DM digestibility, BW, BW gain, or percentages of milk fat, protein, or SNF. Ruminal isobutyrate and isovalerate differed by diet; isovalerate was highest in the diet containing soybean meal plus corn gluten meal, probably because of the high Leu content of corn gluten meal. Ruminal NH3 N did not differ. The favorable production response by cows fed dried brewers grains can be explained by a more favorably balanced AA profile in the ruminally undegraded protein than in other diets.
荷斯坦奶牛（n = 24头，9头初产牛）被平均分配到以玉米青贮和高水分玉米为基础的日粮组中，这些日粮单独添加豆粕，或同时添加玉米蛋白粉或干酒糟。在含有两种蛋白质来源的日粮中，每种来源的蛋白质量相似。日粮粗蛋白（CP）和酸性洗涤纤维（ADF）平均分别为16.3%和18.8%，各日粮中不可降解蛋白占CP的百分比分别为33.6%、41.1%和41.8%。分娩后，奶牛先采食3周豆粕日粮作为协变量期，然后采食10周试验日粮，再采食3周豆粕日粮，接着再采食10周试验日粮。采食这些日粮的奶牛产奶量在两个10周期间分别平均为30.9、31.7和34.9千克/天；蛋白质产量分别平均为0.90、0.94和1.02千克/天；干物质采食量分别平均为16.8、18.8和18.2千克/天。对于3.5%乳脂校正乳（FCM）、估计干物质消化率、体重、体重增加量或乳脂肪、蛋白质或非脂固形物（SNF）百分比，日粮间没有差异。瘤胃异丁酸和异戊酸因日粮而异；异戊酸在含有豆粕加玉米蛋白粉的日粮中最高，这可能是由于玉米蛋白粉中亮氨酸含量高。瘤胃氨态氮（NH₃ N）没有差异。饲喂干酒糟的奶牛产生良好生产反应的原因可能是，瘤胃中不可降解蛋白的氨基酸组成比其他日粮更平衡。
