Harmison B, Eastridge M L, Firkins J L
Department of Animal Sciences, Ohio State University, Columbus 43210, USA.
J Dairy Sci. 1997 May;80(5):905-11. doi: 10.3168/jds.S0022-0302(97)76013-2.
Five Jersey cows were used in a 5 x 5 Latin square design to determine the effects of decreasing dietary forage neutral detergent fiber (NDF) and different sources of dietary starch on performance and nutrient digestibilities. The control diet was balanced to consist of 21% forage NDF and 43% nonfiber carbohydrates. Four other diets were balanced to contain 35% nonfiber carbohydrates and either 16 or 11% forage NDF; diets were arranged in a 2 x 2 factorial design with either corn or corn and wheat as the sources of starch. Dry matter intake decreased linearly as forage NDF decreased; however, most of the decrease occurred when forage NDF was reduced from 16 to 11%. Milk production, yield of 4% fat-corrected milk, and percentages of milk fat and protein were similar among diets. Digestibility of NDF and acid detergent fiber increased as forage NDF decreased, but fiber digestibilities decreased with the addition of wheat to the diets. Starch digestibility was similar among diets. Source and amount of starch may be equally important or more important than the percentage of forage NDF for maintaining nutrient digestibilities of the total tract. Forage NDF in the diets of high producing cows can be reduced to 16% when sources and concentrations of starch are adequately balanced.
选用5头泽西奶牛，采用5×5拉丁方设计，以确定降低日粮中性洗涤纤维（NDF）和不同来源的日粮淀粉对奶牛生产性能和养分消化率的影响。对照日粮的配方为含有21%的饲草NDF和43%的非纤维碳水化合物。其他四种日粮的配方为含有35%的非纤维碳水化合物以及16%或11%的饲草NDF；日粮采用2×2析因设计，以玉米或玉米与小麦作为淀粉来源。随着饲草NDF的降低，干物质采食量呈线性下降；然而，大部分下降发生在饲草NDF从16%降至11%时。各日粮间的产奶量、4%乳脂校正乳产量以及乳脂和乳蛋白百分比相似。随着饲草NDF的降低，NDF和酸性洗涤纤维的消化率升高，但日粮中添加小麦后纤维消化率降低。各日粮间淀粉消化率相似。对于维持全消化道养分消化率而言，淀粉的来源和数量可能与饲草NDF的比例同等重要或更为重要。当日粮中淀粉的来源和浓度得到充分平衡时，高产奶牛日粮中的饲草NDF可降至16%。
