Fredin S M, Akins M S, Ferraretto L F, Shaver R D
Department of Dairy Science, University of Wisconsin, Madison 53706.
Department of Dairy Science, University of Wisconsin, Madison 53706.
J Dairy Sci. 2015 Jan;98(1):554-65. doi: 10.3168/jds.2014-8592. Epub 2014 Nov 7.
An experiment was conducted to evaluate the effects of corn-based dietary starch content and source of neutral detergent fiber (NDF) on lactation performance, nutrient digestion, bacterial protein flow, and ruminal parameters in lactating dairy cows. Eight ruminally cannulated multiparous Holstein cows averaging 193±11d in milk were randomly assigned to treatments in a replicated 4×4 Latin square design with 21-d periods. Treatment diets were high corn grain (HCG; 38% corn silage, 19% dry ground corn, and 4% soy hulls), high soy hulls (HSH; 38% corn silage, 11% dry ground corn, and 13% soy hulls), high corn silage (HCS; 50% corn silage, 6% dry ground corn, and 4% soy hulls), and low corn silage (LCS; 29% corn silage, 15% corn, and 19% soy hulls). The HCG, HSH, HCS, and LCS diets contained 29, 23, 24, and 22% starch; 27, 32, 30, and 32% total NDF; and 21, 21, 25, and 17% forage NDF (dry matter basis), respectively. Mean dry matter intake and milk yield were unaffected by treatment. Cows fed LCS had reduced milk fat content compared with HSH and HCS. The concentration of milk urea nitrogen was greater for cows fed HCS compared with the other treatments. Total-tract digestion of NDF was reduced for cows fed the HCG diet. Total-tract starch digestion was increased for cows fed the HSH and HCS compared with HCG and LCS diets. Bacterial protein flow was unaffected by treatment. Ruminal ammonia concentration was reduced in cows fed the HCG and LCS diets compared with the HCS diet. Ruminal propionate increased and the acetate:propionate ratio decreased in cows fed the LCS diet compared with the HCS diet. Ruminal pH was greater for cows fed the HCS diet compared with cows fed the LCS diet. Diet digestibility and performance of mid- to late-lactation cows fed reduced-starch diets by partially replacing corn grain with soy hulls or corn silage was similar to or improved compared with cows fed a normal-starch diet.
进行了一项试验，以评估基于玉米的日粮淀粉含量和中性洗涤纤维（NDF）来源对泌乳奶牛泌乳性能、养分消化、细菌蛋白流量和瘤胃参数的影响。八头平均产奶193±11天的瘤胃插管经产荷斯坦奶牛，按照重复4×4拉丁方设计，随机分配到各处理组，试验期为21天。处理日粮分别为高玉米谷物（HCG；38%玉米青贮、19%干磨玉米和4%大豆皮）、高大豆皮（HSH；38%玉米青贮、11%干磨玉米和13%大豆皮）、高玉米青贮（HCS；50%玉米青贮、6%干磨玉米和4%大豆皮）和低玉米青贮（LCS；29%玉米青贮、15%玉米和19%大豆皮）。HCG、HSH、HCS和LCS日粮的淀粉含量分别为29%、23%、24%和22%；总NDF分别为27%、32%、30%和32%；饲草NDF（干物质基础）分别为21%、21%、25%和17%。平均干物质采食量和产奶量不受处理的影响。与HSH和HCS相比，饲喂LCS的奶牛乳脂含量降低。与其他处理相比，饲喂HCS的奶牛乳尿素氮浓度更高。饲喂HCG日粮的奶牛NDF全肠道消化率降低。与HCG和LCS日粮相比，饲喂HSH和HCS的奶牛全肠道淀粉消化率提高。细菌蛋白流量不受处理的影响。与HCS日粮相比，饲喂HCG和LCS日粮的奶牛瘤胃氨浓度降低。与HCS日粮相比，饲喂LCS日粮的奶牛瘤胃丙酸增加，乙酸:丙酸比值降低。与饲喂LCS日粮的奶牛相比，饲喂HCS日粮的奶牛瘤胃pH值更高。用大豆皮或玉米青贮部分替代玉米谷物，饲喂低淀粉日粮的泌乳中期至后期奶牛的日粮消化率和生产性能与饲喂正常淀粉日粮的奶牛相似或有所提高。
