Calsamiglia S, Caja G, Stern M D, Crooker B A
Department of Animal Science, University of Minnesota, St. Paul 55108, USA.
J Dairy Sci. 1995 Sep;78(9):1999-2007. doi: 10.3168/jds.S0022-0302(95)76825-4.
Three midlactation Holstein cows with ruminal and duodenal cannulas were used in a 3 x 3 Latin square design to determine whether ruminal or postruminal alterations in metabolism were responsible for the changes in milk composition that frequently are associated with dietary fish meal. Cows were offered a diet of 60:40 forage to concentrate (aliquots at 6-h intervals) that was supplemented with isonitrogenous amounts of soybean meal (1.3 kg of DM/d) dosed into the rumen or fish meal (1.0 kg DM/d) dosed either into the rumen or into the duodenum. The DMI, ruminal NDF digestion, and flows of total N and microbial N to the duodenum decreased for cows receiving fish meal. Dietary N flow increased when fish meal was dosed into the rumen. Total concentration of ruminal VFA was greater for cows receiving the soybean meal treatment; however, treatment had no effect on the ratio of ruminal acetate plus butyrate to propionate. Milk and FCM yields were unaffected by treatment, but milk fat content decreased, and milk protein content increased when cows were supplemented with fish meal. The difference in mammary arteriovenous glucose difference decreased when cows were dosed with fish meal. Changes in plasma NEFA and triglycerides were small and inconsistent. Results from this experiment suggest that effects of fish meal on milk composition are due to postruminal alterations in metabolism.
选用三头处于泌乳中期、安装有瘤胃和十二指肠瘘管的荷斯坦奶牛，采用3×3拉丁方设计，以确定与日粮鱼粉相关的牛奶成分变化是由瘤胃还是瘤胃后代谢变化引起的。给奶牛提供60:40的粗饲料与精饲料比例的日粮（每隔6小时等分投喂），并分别向瘤胃内添加等氮量的豆粕（1.3千克干物质/天）或向瘤胃或十二指肠内添加鱼粉（1.0千克干物质/天）。采食鱼粉的奶牛干物质采食量、瘤胃中性洗涤纤维消化率以及进入十二指肠的总氮和微生物氮流量均降低。当鱼粉添加到瘤胃中时，日粮氮流量增加。采食豆粕处理的奶牛瘤胃挥发性脂肪酸总浓度更高；然而，处理对瘤胃乙酸和丁酸与丙酸的比例没有影响。产奶量和校正乳产量不受处理影响，但添加鱼粉时牛奶脂肪含量降低，牛奶蛋白质含量增加。给奶牛投喂鱼粉时，乳腺动静脉葡萄糖差值减小。血浆非酯化脂肪酸和甘油三酯的变化较小且不一致。本实验结果表明，鱼粉对牛奶成分的影响是由于瘤胃后代谢变化所致。
