Knapp D M, Grummer R R
Department of Dairy Science, University of Wisconsin, Madison 53706.
J Dairy Sci. 1991 Aug;74(8):2573-9. doi: 10.3168/jds.S0022-0302(91)78435-X.
Effects of supplemental prilled long-chain fatty acids on lactation performance during heat stress were examined using eight multiparous Holstein cows in a replicated 4 x 4 Latin square design with 15-d periods. Cows were ruminally cannulated and were assigned randomly to one of four treatments in a 2 x 2 factorial arrangement of treatments. Factors were 0 or 5% supplemental fat and thermoneutral or heat stress conditions. Cows were housed in environmental chambers with thermoneutral conditions of 20.5 degrees C and 38% relative humidity for 24 h/d or heat stress conditions of 31.8 degrees C and 56% relative humidity for 14 h/d and 25.9 degrees C with 56% relative humidity for 10 h/d. Isonitrogenous diets (17% CP) containing 50% alfalfa silage and 50% concentrate were offered for ad libitum intake. Diets contained 1.64 or 1.83 Mcal NEL/kg DM. No diet by environment interactions were significant. Milk fat percentage (3.46 vs. 3.15%) and 3.5% FCM (31.5 vs. 29.2 kg/d) were higher for cows fed 5 vs. 0% fat. Dry matter intake, milk yield, and milk protein percentage did not differ between diets. Heat stress decreased DMI, milk yield, 3.5% FCM, and milk protein percentage but did not affect milk fat percentage. Results suggest that supplemental fat at 5% of diet DM enhances lactation performance similarly under thermoneutral and heat stress conditions.
使用8头经产荷斯坦奶牛，采用重复的4×4拉丁方设计，每个周期15天，研究了添加粒状长链脂肪酸对热应激期间泌乳性能的影响。奶牛安装了瘤胃瘘管，并按照2×2析因处理安排随机分配到四种处理之一。因素为0%或5%的补充脂肪以及热中性或热应激条件。奶牛被安置在环境舱中，热中性条件为20.5摄氏度和38%相对湿度，每天24小时；或热应激条件为31.8摄氏度和56%相对湿度，每天14小时，以及25.9摄氏度和56%相对湿度，每天10小时。提供含50%苜蓿青贮和50%精料的等氮日粮（17%粗蛋白），任其自由采食。日粮含有1.64或1.83兆卡净能/千克干物质。日粮与环境之间没有显著的交互作用。饲喂5%脂肪的奶牛的乳脂率（3.46%对3.15%）和3.5%乳脂校正乳（31.5对29.2千克/天）高于饲喂0%脂肪的奶牛。日粮之间的干物质采食量、产奶量和乳蛋白率没有差异。热应激降低了干物质采食量、产奶量、3.5%乳脂校正乳和乳蛋白率，但不影响乳脂率。结果表明，日粮干物质的5%补充脂肪在热中性和热应激条件下对泌乳性能的提高作用相似。
