Wang Erdan, Cha Manqian, Wang Shuo, Wang Qianqian, Wang Yajing, Li Shengli, Wang Wei
State Key Laboratory of Animal Nutrition, Beijing Engineering Technology Research Center of Raw Milk Quality and Safety Control, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China.
Key Laboratory of Feed Biotechnology of the Ministry of Agriculture and Rural Affairs, Institute of Feed Research, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
Foods. 2023 Jan 9;12(2):303. doi: 10.3390/foods12020303.
Different dietary forage sources regulate health-promoting fatty acids (HPFAs), such as conjugated linoleic acids (CLAs) and omega-3 polyunsaturated fatty acids (n-3 PUFAs), in the milk of lactating cows. However, the overall mechanism of forages regulating lipid metabolism from the gastrointestinal tract to the mammary glands (MGs) is not clear. Three isocaloric diets that contained (1) 46% corn silage (CS), (2) a mixture of 23% corn silage and 14% grass hays (MIX), and (3) 28% grass hays (GH) as the forage sources and six cannulated (rumen, proximal duodenum, and terminal ileum) lactating cows were assigned to a double 3 × 3 Latin square design. Our results show that a higher proportion of grass hay in the diets increased the relative contents of short-chain fatty acids (SCFAs), CLAs, and n-3 PUFAs. The lower relative content of SCFA in the milk of CS was predominantly due to the reduction in acetate production in the rumen and arteriovenous differences in the MG, indicating that the de novo synthesis pathways were inhibited. The elevated relative contents of total CLA and n-3 PUFA in the milk of GH were attributed to the increases in apparent intestinal digestion and arteriovenous differences in total CLA and n-3 PUFA, together with the higher Δ-desaturase activity in the MG. In conclusion, this study provides an overall mechanism of dietary forages regulating HPFA status in the milk of dairy cows.
不同的日粮草料来源可调节泌乳奶牛乳汁中促进健康的脂肪酸（HPFAs），如共轭亚油酸（CLAs）和ω-3多不饱和脂肪酸（n-3 PUFAs）。然而，草料从胃肠道到乳腺（MGs）调节脂质代谢的整体机制尚不清楚。三种等热量日粮分别含有（1）46%玉米青贮（CS）、（2）23%玉米青贮和14%禾本科干草的混合物（MIX）、（3）28%禾本科干草（GH）作为草料来源，并将六头安装了瘘管（瘤胃、十二指肠近端和回肠末端）的泌乳奶牛分配到双3×3拉丁方设计中。我们的结果表明，日粮中较高比例的禾本科干草增加了短链脂肪酸（SCFAs）、共轭亚油酸和n-3多不饱和脂肪酸的相对含量。CS组奶牛乳汁中SCFA相对含量较低主要是由于瘤胃中乙酸盐生成减少以及乳腺中动静脉差异，这表明从头合成途径受到抑制。GH组奶牛乳汁中共轭亚油酸和n-3多不饱和脂肪酸总量的相对含量升高归因于共轭亚油酸和n-3多不饱和脂肪酸的表观肠道消化增加以及动静脉差异，以及乳腺中较高的Δ-去饱和酶活性。总之，本研究提供了日粮草料调节奶牛乳汁中HPFA状态的整体机制。
