Overton T R, LaCount D W, Cicela T M, Clark J H
Department of Animal Sciences, University of Illinois, Urbana 61801, USA.
J Dairy Sci. 1996 Apr;79(4):631-8. doi: 10.3168/jds.S0022-0302(96)76408-1.
In Experiment 1, three ruminally and duodenally cannulated cows were used to assess the extent of ruminal protection and postruminal release of Met from ruminally protected Met using a polyester bag technique. The ruminally protected Met contained 85.1% DL-Met (wt/wt). Ruminal disappearance of Met averaged 5.8, 8.1, 21.8, 37.5, and 87.5% after 3, 6, 12, 24, and 96 h of incubation, respectively. Postruminal disappearance of Met from bags inserted in the duodenum after treatment with pepsin-HCl averaged 63.4, 62.6, 51.6, 43.6, and 8.8% for bags incubated in the rumen for 3, 6, 12, 24, and 96 h, respectively. In Experiment 2, 12 cows were fed either 0 or 20 g/d of ruminally protected Met from 7 to 10 d prepartum until 18 wk postcalving. Cows were fed the same total mixed diet. The DMI; yields of milk, CP, and SNF; and percentages of fat, CP, and SNF in milk were not affected by treatment. However, yields of fat and 3.5% FCM increased when ruminally protected Met was fed. Milk N components were not affected by treatment. Concentrations of Met increased in plasma when ruminally protected Met was fed. The mechanism for the increased production of milk fat and 3.5% FCM when ruminally protected Met was fed is unknown.
在实验1中，使用3头安装有瘤胃和十二指肠瘘管的奶牛，采用聚酯袋技术评估瘤胃保护性蛋氨酸（Met）在瘤胃中的保护程度以及瘤胃后释放情况。瘤胃保护性Met含有85.1%的DL-蛋氨酸（重量/重量）。Met在瘤胃中的消失率在孵育3、6、12、24和96小时后分别平均为5.8%、8.1%、21.8%、37.5%和87.5%。用胃蛋白酶-盐酸处理后，在十二指肠插入的袋子中，Met从瘤胃中孵育3、6、12、24和96小时的袋子中的瘤胃后消失率分别平均为63.4%、62.6%、51.6%、43.6%和8.8%。在实验2中，12头奶牛在产前7至10天至产后18周期间，每天分别饲喂0或20克瘤胃保护性Met。奶牛饲喂相同的全混合日粮。干物质采食量；牛奶、粗蛋白（CP）和非脂固形物（SNF）的产量；以及牛奶中脂肪、CP和SNF的百分比不受处理的影响。然而，饲喂瘤胃保护性Met时，脂肪和3.5%乳脂校正乳（FCM）的产量增加。牛奶中的氮成分不受处理的影响。饲喂瘤胃保护性Met时，血浆中Met的浓度增加。饲喂瘤胃保护性Met时牛奶脂肪和3.5% FCM产量增加的机制尚不清楚。
