Polan C E, Herrington T A, Miller C N
J Dairy Sci. 1985 Jul;68(7):1696-705. doi: 10.3168/jds.S0022-0302(85)81015-8.
Twenty-four first-lactation cows, averaging 82 d postpartum, were protein depleted for 20 d by consuming a 9.4% crude protein diet. The cows were then assigned randomly and equally to a 2 X 3 factorial arrangement of dietary treatments in which either pelleted or unpelleted soybean meal containing 1% sodium bentonite was supplemented to corn or corn silage-based diets to yield 12.2, 15.4, or 18.1% crude protein, dry basis. Between 9 and 15 d of the depletion period, milk, milk protein production, and dry matter consumption decreased 20 to 25%. Blood hematocrit increased. On refeeding three amounts of protein, dry matter intake was greatest during week 4 of repletion. Milk production rapidly increased to a plateau averaging approximately 88% of preexperimental production with a somewhat greater response to the higher soybean rations. Neither intake, milk, milk protein production, plasma urea, serum albumin, or blood hematocrit provided any evidence that pelleted or unpelleted soybean meal differed nutritionally.
24头头胎奶牛，平均产后82天，通过采食粗蛋白含量为9.4%的日粮使蛋白质缺乏20天。然后将这些奶牛随机且等分为2×3析因设计的日粮处理组，在以玉米或玉米青贮为基础的日粮中添加含1%钠膨润土的颗粒或非颗粒豆粕，使干物质基础的粗蛋白含量达到12.2%、15.4%或18.1%。在缺乏期的第9至15天，牛奶产量、乳蛋白产量和干物质采食量下降了20%至25%。血细胞比容升高。重新饲喂三种水平的蛋白质后，复饲第4周干物质摄入量最大。牛奶产量迅速增加至平台期，平均约为实验前产量的88%，对较高豆粕日粮的反应稍大。采食量、牛奶产量、乳蛋白产量、血浆尿素、血清白蛋白或血细胞比容均未提供任何证据表明颗粒或非颗粒豆粕在营养上存在差异。
