Overton T R, Cameron M R, Elliott J P, Clark J H, Nelson D R
Department of Animal Sciences, University of Illinois, Urbana 61801, USA.
J Dairy Sci. 1995 Sep;78(9):1981-98. doi: 10.3168/jds.s0022-0302(95)76824-2.
Five Holstein cows were used in a 5 x 5 Latin square design and fed diets containing five different ratios of starch from ground shelled corn and steam-rolled barley. The DMI decreased and both the proportions of OM and starch digested in the rumen increased as barley starch increased in the diet. Corn and barley starches fed in a ratio of 75:25 maximized the proportions of ADF and NDF digested in the rumen. Replacement of 25% of the corn starch with barley starch resulted in the largest increase in the molar percentage of propionate and the largest decrease in the molar percentage of acetate in ruminal fluid. Passage of NAN to the duodenum was not affected by treatment; however, the percentage of nonammonia nonmicrobial N in NAN decreased as barley starch increased. Passage of AA to the duodenum was largest when corn and barley starches were fed in ratios of 100: 0 and 0:100 because of the influence of DMI and microbial protein synthesis. Production of Milk, CP, and SNF was similar when cows were fed diets containing corn and barley starches in ratios of 100:0, 75:25, and 50:50 but was decreased when the ratios were 25:75 and 0:100. Increased production responses of cows when diets contained larger amounts of starch from ground shelled corn were probably due to increased DMI.
选用5头荷斯坦奶牛，采用5×5拉丁方设计，给它们饲喂含有5种不同比例的来自粉碎脱壳玉米和蒸汽压片大麦淀粉的日粮。随着日粮中大麦淀粉含量的增加，干物质采食量（DMI）下降，瘤胃中消化的有机物（OM）和淀粉比例均增加。玉米和大麦淀粉以75:25的比例饲喂时，瘤胃中消化的酸性洗涤纤维（ADF）和中性洗涤纤维（NDF）比例最高。用25%的大麦淀粉替代玉米淀粉，导致瘤胃液中丙酸的摩尔百分比增加最大，乙酸的摩尔百分比下降最大。非氨氮（NAN）进入十二指肠的量不受处理的影响；然而，随着大麦淀粉含量的增加，NAN中非氨非微生物氮的百分比下降。由于DMI和微生物蛋白质合成的影响，当玉米和大麦淀粉以100:0和0:100的比例饲喂时，氨基酸（AA）进入十二指肠的量最大。当奶牛饲喂含有比例为100:0、75:25和50:50的玉米和大麦淀粉的日粮时，牛奶、粗蛋白（CP）和非脂固形物（SNF）的产量相似，但当比例为25:75和0:100时产量下降。当日粮中含有较多来自粉碎脱壳玉米的淀粉时，奶牛生产性能的提高可能是由于DMI增加所致。
