State Key Laboratory of Animal Nutrition, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100193, P. R. China.
J Dairy Sci. 2010 Apr;93(4):1677-84. doi: 10.3168/jds.2009-2681.
Increasing the alpha-linolenic acid (LNA; 18:3 cis-9,cis-12,cis-15) content of milk fat might help promote consumers' health. The objective of this study was to determine the potential to alter the content of LNA in milk by duodenal infusion of a free fatty acid mixture rich in LNA. Four multiparous lactating Chinese Holstein cows fitted with duodenal cannulas were administered 2 treatments in a crossover design: an LNA-rich fatty acid infusion at varying concentrations (0, 40, 80, 120, and 160 g/d) versus a basal infusate control. Dry matter intake was not affected by LNA infusions. Milk production tended to decrease and was quadratically affected as LNA infusion increased, but 4% fat-corrected milk yield was not changed. Milk fat content tended to increase linearly with LNA infusion. Milk protein content was not changed by LNA infusion, whereas milk lactose content and yield were decreased quadratically as LNA infusion increased. Increasing the amount of LNA infused into the duodenum linearly increased concentrations of 18:3 cis-9,cis-12,cis-15 (0.61 to 25.4 g/100g of total fatty acids) and 18:2 cis-9,cis-12 in milk fat. Increasing LNA decreased the percentages of 4:0, 14:0, and 16:0 fatty acids linearly. Increasing LNA also linearly decreased the percentages of 18:1 cis-9 and 18:2 cis-9,trans-11 in milk fat. Milk fat content of 20:5 cis-5,cis-8,cis-11,cis-14,cis-17 was quadratically affected, whereas concentrations of 18:0, 18:1 trans-9, 18:1 trans-11, and 18:2 trans-10,cis-12 were not affected. Increasing the supply of 18:3 cis-9,cis-12,cis-15 to the small intestine linearly increased 18:3 cis-9,cis-12,cis-15 in milk fat and markedly altered milk fat composition.
增加牛奶脂肪中的α-亚麻酸（LNA；18:3 顺式-9,顺式-12,顺式-15）含量可能有助于促进消费者健康。本研究的目的是通过十二指肠输注富含 LNA 的游离脂肪酸混合物来确定改变牛奶中 LNA 含量的潜力。4 头泌乳期中国荷斯坦奶牛通过十二指肠插管进行了两种处理的交叉设计：LNA 丰富的脂肪酸输注以不同浓度（0、40、80、120 和 160 g/d）与基础输注对照。LNA 输注不会影响干物质摄入量。产奶量随着 LNA 输注的增加而趋于下降，并呈二次曲线影响，但 4%脂肪校正奶产量没有变化。牛奶脂肪含量随着 LNA 输注呈线性增加。LNA 输注不会改变牛奶蛋白含量，而牛奶乳糖含量和产量随着 LNA 输注的增加呈二次曲线下降。十二指肠内注入的 LNA 量增加呈线性增加牛奶脂肪中 18:3 顺式-9,顺式-12,顺式-15（0.61 至 25.4 g/100g 总脂肪酸）和 18:2 顺式-9,顺式-12 的浓度。增加 LNA 会使牛奶脂肪中的 4:0、14:0 和 16:0 脂肪酸百分比线性下降。增加 LNA 也会使牛奶脂肪中的 18:1 顺式-9 和 18:2 顺式-9,反式-11 百分比线性下降。牛奶脂肪中 20:5 顺式-5,顺式-8,顺式-11,顺式-14,顺式-17 呈二次曲线影响，而 18:0、18:1 反式-9、18:1 反式-11 和 18:2 反式-10,顺式-12 则不受影响。向小肠供应更多的 18:3 顺式-9,顺式-12,顺式-15 会使牛奶脂肪中的 18:3 顺式-9,顺式-12,顺式-15 增加，并显著改变牛奶脂肪成分。
