Abstract: This study analyzed the effect of season on the nutrient and fatty acid composition of yak milk. Yak milk samples from the Qinghai-Tibet Plateau in summer and winter (n = 18, each) were selected for this study. Results showed that the contents of protein, lactose, non-fat milk solid, ash, vitamin A and main trans fatty acids (trans-9 C18:1 and trans-9,12 C18:2 n-6) were significantly lower in winter than in summer (P < 0.05), while the contents of fat and main fatty acids (C16:0, C17:0, C18:0, cis-9 C16:1, cis-9 C18:1 and cis-9,12 C18:2 n-6) in yak milk were significantly higher in winter than in summer. This suggests that the nutrient and fatty acids composition of yak milk from the Qinghai-Tibet Plateau are influenced by season.

Key words: yak milk; nutrient composition; fat; fatty acid; season

摘要： 选择生活在高海拔（平均海拔4 200 m以上）的青海高原型牦牛（夏季，n=18；冬季，n=18）分析季节对牦牛乳营养成分和脂肪酸组成的影响。结果表明：蛋白质、乳糖、非脂乳固体、灰分、VA和主要反式脂肪酸（反-9-C18:1和反-9,12-C18:2 n-6）含量冬季显著低于夏季（P＜0.05），而脂肪和主要脂肪酸（C16:0、C17:0、C18:0、顺-9-C16:1、顺-9-C18:1和顺-9,12-C18:2 n-6）含量冬季显著高于夏季（P＜0.05），说明青海高原型牦牛乳的营养成分和脂肪酸组成受季节的影响。

关键词: 牦牛乳；营养成分；脂肪；脂肪酸；季节