Embrapa Beef Cattle, Campo Grande, Mato Grosso do Sul, Brazil.
J Dairy Sci. 2010 Mar;93(3):1126-37. doi: 10.3168/jds.2009-2645.
Conjugated linoleic acids (CLA) are potent anticarcinogens in animal and in vitro models as well as inhibitors of fatty acid synthesis in mammary gland, liver, and adipose tissue. Our objective was to evaluate long-term CLA supplementation of lactating dairy cows in tropical pasture on milk production and composition and residual effects posttreatment. Thirty crossbred cows grazing stargrass (Cynodon nlemfuensis Vanderyst var. nlemfüensis) were blocked by parity and received 150 g/d of a dietary fat supplement of either Ca-salts of palm oil fatty acids (control) or a mixture of Ca-salts of CLA (CLA treatment). Supplements of fatty acids were mixed with 4 kg/d of concentrate. Grazing plus supplements were estimated to provide 115% of the estimated metabolizable protein requirements from 28 to 84 d in milk (treatment period). The CLA supplement provided 15 g/d of cis-9,trans-11 and 22g of cis-10,trans-12. Residual effects were evaluated from 85 to 112 d in milk (residual period) when cows were fed an 18% crude protein concentrate without added fat. The CLA treatment increased milk production but reduced milk fat concentration from 2.90 to 2.14% and fat production from 437 to 348 g/d. Milk protein concentration increased by 11.5% (2.79 to 3.11%) and production by 19% (422 to 504 g/d) in the cows fed CLA. The CLA treatment decreased milk energy concentration and increased milk volume, resulting in unchanged energy output. Milk production and protein concentration and production were also greater during the residual period for the CLA-treated cows. The CLA treatment reduced production of fatty acids (FA) of all chain lengths, but the larger effect was on short-chain FA, causing a shift toward a greater content of longer chain FA. The CLA treatment increased total milk CLA content by 30% and content of the trans-10,cis-12 CLA isomer by 88%. The CLA treatment tended to decrease the number of days open, suggesting a possible effect on reproduction. Under tropical grazing conditions, in a nutritionally challenging environment, CLA-treated cows decreased milk fat content and secreted the same amount of milk energy by increasing milk volume and milk protein production.
共轭亚油酸（CLA）在动物和体外模型中是有效的抗癌物质，也是乳腺、肝脏和脂肪组织中脂肪酸合成的抑制剂。我们的目的是评估在热带牧场泌乳奶牛中进行 CLA 补充的长期效果，以评估其对产奶量和组成的影响以及治疗后的残留效果。30 头杂交奶牛按胎次分组，用棕榈酸钙盐（对照组）或 CLA 钙盐混合物（CLA 处理组）的 150g/d 日粮脂肪补充剂进行处理。脂肪酸补充剂与 4kg/d 的浓缩饲料混合。从第 28 天到第 84 天，放牧加补充剂估计能提供 115%的代谢蛋白需求量（处理期）。CLA 补充剂每天提供 15g 的顺式-9，反式-11 和 22g 的顺式-10，反式-12。当奶牛在没有添加脂肪的 18%粗蛋白浓缩物中饲养时，从第 85 天到第 112 天（残留期）评估残留效果。CLA 处理增加了产奶量，但降低了乳脂浓度（从 2.90%降至 2.14%）和脂肪产量（从 437g/d 降至 348g/d）。CLA 处理组的牛奶蛋白浓度增加了 11.5%（从 2.79%升至 3.11%），产量增加了 19%（从 422g/d 增至 504g/d）。CLA 处理降低了牛奶的能量浓度，增加了牛奶量，从而使能量输出保持不变。CLA 处理奶牛在残留期的产奶量和蛋白浓度以及产量也更高。CLA 处理减少了所有链长的脂肪酸（FA）的产生，但对短链 FA 的影响更大，导致更长链 FA 的含量增加。CLA 处理使牛奶中总 CLA 含量增加了 30%，反式-10，顺式-12 CLA 异构体的含量增加了 88%。CLA 处理倾向于减少发情天数，这表明它可能对繁殖有影响。在热带放牧条件下，在营养挑战的环境中，CLA 处理奶牛通过增加牛奶量和牛奶蛋白产量来降低乳脂含量，同时产生相同数量的牛奶能量。
