Joy M T, DePeters E J, Fadel J G, Zinn R A
Department of Animal Science, University of California, Davis 95616-8521, USA.
J Dairy Sci. 1997 Sep;80(9):2087-97. doi: 10.3168/jds.S0022-0302(97)76154-X.
Three multiparous Holstein cows in midlactation were fitted with ruminal and duodenal cannulas. Cows were used in an experiment with a 3 x 3 Latin square design to study the effect of corn processing on nutrient flow from the rumen to the duodenum and on ruminal fermentation in lactating cows. Cows were fed diets consisting of 40% forage and 60% concentrate. The only difference in dietary ingredients was the type of processed corn included at 24% of the total diet (as-fed basis). Treatments were dry-rolled corn with a bulk density of 0.54 kg/L and steam-flaked corn with a bulk density of either 0.39 kg/L or 0.31 kg/L. Ruminal fluid pH was not affected by corn processing, but steam-flaking decreased the molar percentage of acetate and increased the molar percentage of propionate. Digestibility of starch in the rumen was not affected by processing. Digestibility of starch entering the duodenum as well as apparent digestibility of starch in the total tract were increased by steam-flaking. Flow of feed and microbial N from the rumen and microbial N efficiency were not affected by grain processing. Yields of milk and milk components as well as composition of milk were not affected by grain processing.
三头处于泌乳中期的经产荷斯坦奶牛安装了瘤胃和十二指肠瘘管。奶牛用于一项采用3×3拉丁方设计的试验，以研究玉米加工对泌乳奶牛从瘤胃到十二指肠的养分流动以及瘤胃发酵的影响。给奶牛饲喂由40%粗饲料和60%精饲料组成的日粮。日粮成分的唯一差异是占总日粮（风干基础）24%的加工玉米类型。处理组分别为容重0.54 kg/L的干碾压玉米以及容重分别为0.39 kg/L或0.31 kg/L的蒸汽压片玉米。瘤胃液pH不受玉米加工的影响，但蒸汽压片降低了乙酸的摩尔百分比并提高了丙酸的摩尔百分比。瘤胃中淀粉的消化率不受加工的影响。蒸汽压片提高了进入十二指肠的淀粉消化率以及全消化道中淀粉的表观消化率。瘤胃中饲料和微生物氮的流量以及微生物氮效率不受谷物加工的影响。牛奶及牛奶成分的产量以及牛奶组成不受谷物加工的影响。
