Armentano L E, Bertics S J, Ducharme G A
Department of Dairy Science, University of Wisconsin, Madison 53706-1284, USA.
J Dairy Sci. 1997 Jun;80(6):1194-9. doi: 10.3168/jds.S0022-0302(97)76047-8.
Lactation diets based on wilted alfalfa silage and heated whole soybeans are common in the midwestern US. We examined the milk production response of multiparous Holstein cows to the addition of ruminally protected methionine at two percentages to a basal total mixed ration. An additional total mixed ration included both methionine and lysine supplementation. Sixteen Holstein cows in early lactation were used in a replicated 4 x 4 Latin square design with 21-d periods. Milk production, milk composition, and dry matter intake were determined for the last 5 d of each period. Milk production (41.5 kg/d), dry matter intake (25.9 kg/d), and milk fat concentration (3.26%) were unaffected by the supplementation of amino acids. The addition of methionine increased milk protein concentration and yield linearly. Each gram of methionine increased milk protein yield by 4 g, and milk protein concentration increased from 2.89 to 2.99% with the addition of 10.5 g/d of methionine. The proportion of casein N in total milk N was unaffected by treatment. The addition of lysine did not elicit a response. Total mixed rations based on alfalfa haylage, heated soybeans, and animal proteins were clearly limited by their methionine content but were adequate in their lysine content.
在美国中西部，以萎蔫苜蓿青贮料和加热全脂大豆为基础的泌乳日粮很常见。我们研究了经产荷斯坦奶牛对在基础全混合日粮中添加两种比例的瘤胃保护蛋氨酸的产奶反应。另一种全混合日粮同时添加了蛋氨酸和赖氨酸。16头处于泌乳早期的荷斯坦奶牛采用重复4×4拉丁方设计，每期21天。在每个周期的最后5天测定产奶量、奶成分和干物质摄入量。氨基酸添加对产奶量（41.5千克/天）、干物质摄入量（25.9千克/天）和乳脂浓度（3.26%）没有影响。添加蛋氨酸使乳蛋白浓度和产量呈线性增加。每克蛋氨酸使乳蛋白产量增加4克，添加10.5克/天蛋氨酸时，乳蛋白浓度从2.89%提高到2.99%。酪蛋白氮占总乳氮的比例不受处理影响。添加赖氨酸未引起反应。以苜蓿青贮料、加热大豆和动物蛋白为基础的全混合日粮显然受蛋氨酸含量限制，但赖氨酸含量充足。
