State Key Laboratory of Animal Nutrition, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, P. R. China.
J Agric Food Chem. 2010 Mar 24;58(6):3741-6. doi: 10.1021/jf903128j.
Increasing the content of alpha-linolenic acid in milk fat might be desirable to meet consumer concerns about dietary healthfulness. However, the rich content of polyunsaturated fatty acids (PUFAs) will influence the oxidative stability of milk fat. This experiment was carried out to determine the effects of infusion with different amounts of high-linolenic perilla fatty acid (HLPFA) emulsion into the duodenum of dairy cows on milk fatty acid profile and the susceptibility of milk fat to oxidation. In a crossover design, 4 multiparous Holstein cows were infused duodenally with increasing amounts (0, 40, 80, 120, or 160 g/day) of free fatty acids from HLPFA emulsion or with carrier alone. Continuous infusions (20 to 22 h/day) were for 7 days at each amount. Infusions were homogenates of HLPFA with 15 g/day of xanthan gum, 5 g/day sodium alginate, and 25 g/day Tween 80; controls received carrier only. The concentration of n-3 PUFAs, especially alpha-linolenic acid, in milk fat increased linearly as HLPFA infusion increased, but the saturated fatty acids decreased linearly. The milk production and the activity of superoxide dismutase, glutathione peroxidase, and catalase in milk tended to decrease quadratically. The milk fat percentage, however, tended to increase. The concentration of malondialdehyde increased quadratically in milk fat. Results suggest that infusion with HLPFA emulsion at varying amounts enhanced the content of n-3 PUFAs in milk fat over the length of experiment but decreased the oxidative stability of milk fat.
增加牛奶脂肪中的α-亚麻酸含量可能是为了满足消费者对饮食健康的关注。然而，多不饱和脂肪酸（PUFAs）的丰富含量会影响牛奶脂肪的氧化稳定性。本实验旨在确定不同剂量的高亚麻酸紫苏脂肪酸（HLPFA）乳液十二指肠输注对奶牛乳脂肪酸谱和乳脂肪氧化敏感性的影响。采用交叉设计，4 头经产荷斯坦奶牛十二指肠输注不同剂量（0、40、80、120 或 160 g/天）的 HLPFA 乳液游离脂肪酸或载体单独输注。在每个剂量下，连续输注（20 至 22 小时/天）持续 7 天。输注物是 HLPFA 与 15 g/天黄原胶、5 g/天海藻酸钠和 25 g/天吐温 80 的混合物；对照物仅接受载体。牛奶脂肪中 n-3PUFAs，特别是α-亚麻酸的浓度随着 HLPFA 输注的增加而呈线性增加，而饱和脂肪酸则呈线性减少。牛奶产量和牛奶中超氧化物歧化酶、谷胱甘肽过氧化物酶和过氧化氢酶的活性呈二次趋势下降。然而，牛奶脂肪百分比呈上升趋势。牛奶脂肪中的丙二醛浓度呈二次增加。结果表明，在实验过程中，HLPFA 乳液的不同剂量输注可增加牛奶脂肪中 n-3PUFAs 的含量，但降低牛奶脂肪的氧化稳定性。
