Erdman R A, Vandersall J H, Russek-Cohen E, Switalski G
J Anim Sci. 1987 Feb;64(2):565-77. doi: 10.2527/jas1987.642565x.
Three ruminal-cannulated Holstein cows in early lactation were fed three diets, each containing different energy and protein supplements in two consecutive 3 X 3 Latin squares. Each supplement contained a combination of three different feedstuffs (ground corn, soybean meal and wheat mids; corn gluten feed, rolled oats and distiller's dried grains; ground barley, brewer's grains and cottonseed meal). Diets consisted of 30% corn silage, 10% alfalfa hay, 10% alfalfa haylage, 17.7% ground corn plus minerals and vitamins, with the remainder as supplemental feedstuffs individually marked for measurement of ruminal turnover and in situ digestion rates. An extra period at the end of each Latin square was used to measure ruminal turnover and in situ digestion of individual forages. Diet had no effect on dry matter intake or milk yield. Mean fractional turnover (per hour) rate, measured by labeling feedstuffs with cerium, samarium or lanthanum was .044, .048, .049, .043, .047, .046, .050, .047, .049, .037, .046 and .045 for corn, soybean meal, wheat mids, corn gluten feed, oats, distiller's dried grains with solubles, barley, brewer's dried grains, cottonseed meal, alfalfa hay, corn silage and alfalfa haylage (P greater than .1), respectively. In situ-predicted ruminal degradation of N weighted for rate of passage was 61.4, 67.0, 81.5, 74.8, 86.3, 71.0, 75.7, 52.1, 54.2, 60.8, 71.7 and 70.9% for respective feedstuffs (P less than .05). In comparison with mean literature values for in vivo-measured N degradability, mean literature value = 1.172 (in situ predicted) -9.73 (P less than .05, R2 = .51). Results are interpreted to indicate a tendency for overestimating ruminal N degradability by in situ methods in feedstuffs of low degradability, while underestimating degradability in more highly degraded feedstuffs. Estimates were 11 to 17 percentage units lower than literature values for alfalfa hay and haylage and 17 units lower than literature values for distiller's dried grains.
选用3头处于泌乳早期的安装有瘤胃瘘管的荷斯坦奶牛，采用两个连续的3×3拉丁方设计，给它们饲喂3种日粮，每种日粮含有不同的能量和蛋白质补充料。每种补充料包含3种不同饲料原料的组合（玉米粉、豆粕和小麦麸；玉米蛋白粉、燕麦片和酒糟；大麦粉、啤酒糟和棉籽粕）。日粮由30%的玉米青贮、10%的苜蓿干草、10%的苜蓿半干青贮、17.7%的玉米粉加矿物质和维生素组成，其余为单独标记用于测定瘤胃周转率和原位消化率的补充饲料原料。在每个拉丁方试验结束时增加一个阶段，用于测定每种饲料原料的瘤胃周转率和原位消化情况。日粮对干物质采食量或产奶量没有影响。用铈、钐或镧标记饲料原料测定的平均分数周转率（每小时），玉米、豆粕、小麦麸、玉米蛋白粉、燕麦、带可溶物的酒糟、大麦、啤酒糟、棉籽粕、苜蓿干草、玉米青贮和苜蓿半干青贮分别为0.044、0.048、0.049、0.043、0.047、0.046、0.050、0.047、0.049、0.037、0.046和0.045（P＞0.1）。根据通过速率加权的原位预测瘤胃氮降解率，各饲料原料分别为61.4%、67.0%、81.5%、74.8%、86.3%、71.0%、75.7%、52.1%、54.2%、60.8%、71.7%和70.9%（P＜0.05）。与体内测定的氮降解率的平均文献值相比，平均文献值=1.172（原位预测值）-9.73（P＜0.05，R2=0.51）。结果表明，原位法倾向于高估低降解性饲料原料的瘤胃氮降解率，而低估高降解性饲料原料的降解率。苜蓿干草和半干青贮的估计值比文献值低11至17个百分点，酒糟的估计值比文献值低17个百分点。
