Kreikemeier K K, Harmon D L, Brandt R T, Nagaraja T G, Cochran R C
Kansas State University, Manhattan 66506.
J Anim Sci. 1990 Jul;68(7):2130-41. doi: 10.2527/1990.6872130x.
Two experiments were conducted to determine the influence of dietary roughage concentration and feed intake on finishing steer performance and ruminal metabolism. In Exp. 1, 126 steers (334 kg) were used in a completely randomized design and fed (120 d) diets of steam-rolled wheat without roughage or containing 5, 10 or 15% roughage (50% alfalfa hay:50% corn silage). Steers fed 5 or 10% roughage gained faster (quadratic, P less than .05) and were more efficient (quadratic, P less than .05) than steers fed 15% or no roughage. In Exp. 2, six ruminally cannulated steers (447 kg) were used in a 6 x 6 latin square design and fed (twice daily) diets of steam-rolled wheat without roughage or containing 5 or 15% alfalfa hay at twice or three times NE required for maintenance. Increasing dietary roughage increased (linear, P less than .01) ruminal liquid passage 38%, indigestible ADF passage 63%, Yb-labeled wheat passage 75% and fiber fill 31%. The rate of in situ starch digestion tended to increase (linear, P = .16), and ruminal VFA concentration was 40 mM higher (P less than .01) at 4 h after feeding with increased roughage. Increased feed intake increased (P less than .05) ruminal starch fill, fiber fill, liquid fill and liquid passage 23%, Yb-labeled wheat passage 50% and Dry-labeled hay passage 20%. It reduced protozoa five- to sixfold (P less than .01) but doubled total bacterial counts (P less than .01). Ruminal NH3N was lower (P less than .01) and total VFA concentration was 50 mM higher (P less than .01) at 4 h after feeding. The acetate:propionate ratio was reduced from 2.3 to 1.3 (P less than .01) with increased intake. Adding roughage to a steam-rolled wheat diet increased passage and tended to increase rate of starch digestion; increased feed intake with its associated effects on ruminal fill and passage dramatically shifted the microbial population and fermentation end products.
进行了两项试验，以确定日粮粗饲料浓度和采食量对育肥牛生产性能及瘤胃代谢的影响。在试验1中，126头体重334千克的育肥牛采用完全随机设计，饲喂（120天）不含粗饲料或含有5%、10%或15%粗饲料（50%苜蓿干草：50%玉米青贮）的蒸汽压片小麦日粮。饲喂5%或10%粗饲料的育肥牛比饲喂15%粗饲料或不喂粗饲料的育肥牛增重更快（二次效应，P<0.05）且效率更高（二次效应，P<0.05）。在试验2中，6头安装了瘤胃瘘管的育肥牛（体重447千克）采用6×6拉丁方设计，饲喂（每日两次）不含粗饲料或含有5%或15%苜蓿干草的蒸汽压片小麦日粮，采食量为维持需要量的两倍或三倍。增加日粮粗饲料含量使瘤胃液流通率提高了38%（线性效应，P<0.01）、不可消化酸性洗涤纤维流通率提高了63%、镱标记小麦流通率提高了75%、纤维填充量提高了31%。原位淀粉消化率有提高的趋势（线性效应，P=0.16），增加粗饲料后，采食后4小时瘤胃挥发性脂肪酸（VFA）浓度高出40毫摩尔（P<0.01）。采食量增加使瘤胃淀粉填充量、纤维填充量、液体填充量和液体流通率提高了23%（P<0.05）、镱标记小麦流通率提高了一半、干标记干草流通率提高了20%。采食量增加使原虫数量减少了五至六倍（P<0.01），但使细菌总数增加了一倍（P<0.01）。采食后4小时瘤胃氨态氮含量较低（P<0.01），总挥发性脂肪酸浓度高出50毫摩尔（P<0.01）。随着采食量增加，乙酸与丙酸的比例从2.3降至1.3（P<0.01）。在蒸汽压片小麦日粮中添加粗饲料提高了流通率，且有提高淀粉消化率的趋势；采食量增加及其对瘤胃填充和流通的相关影响极大地改变了微生物种群和发酵终产物。
