Milk fat synthesis in dairy cows is progressively reduced by increasing supplemental amounts of trans-10, cis-12 conjugated linoleic acid (CLA)
Milk fat synthesis in dairy cows is progressively reduced by increasing supplemental amounts of trans-10, cis-12 conjugated linoleic acid (CLA)
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DOI：
10.1093/jn/131.6.1764
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发表时间：
2001-06-01
影响因子：
4.2
通讯作者：
Bauman, DE
中科院分区：
文献类型：
--
作者：
Baumgard, LH;Sangster, JK;Bauman, DE
共轭亚油酸（CLA）补充剂含有各种异构体减少乳脂产量。我们最近已经确定了反式-10，顺式-12共轭亚油酸的异构体负责抑制奶牛乳脂合成。我们的目的是确定乳脂产量和脂肪酸组成的反应，不同剂量的反式，cia-12共轭亚油酸。以4 × 4拉丁方设计使用经产荷斯坦奶牛（n = 4）。治疗包括5天的皱胃输注四个剂量的反式-10，顺式-12 CLA，即，0.0、3.5、7.0和14.0 g/d。当奶牛接受3.5、7.0和14.0 g/d的trans-10、cia-12 CLA时，乳脂产量分别降低25、33和50%，乳脂浓度分别降低24、37和46%。采食量、产奶量、乳蛋白含量和产奶量不受处理影响。牛奶脂肪酸组成显示，当奶牛接受两种最高剂量时，从头合成的脂肪酸（短链和中链）大量减少，但在低剂量（3.5 g/d）下，从头合成的脂肪酸和预先形成的脂肪酸减少相似。牛奶脂肪酸组成的变化也表明，在两个高剂量的反式-10，顺式-12共轭亚油酸的Ag-去饱和酶活性被抑制，但不受低剂量。结果表明，最低量的反式-10，顺式-12共轭亚油酸（0.016%的膳食干物质）显着抑制乳脂合成（减少25%），并发生曲线减少乳脂产量与反式，顺式-12共轭亚油酸的数量增加。
Conjugated linoleic acid (CLA) supplements containing a variety of isomers reduce milk fat yield. We have recently identified trans-10, cis-12 CLA as the isomer responsible for inhibiting milk fat synthesis in dairy cows. Our objectives were to determine milk fat yield and fatty acid composition responses to different doses of trans-in, cia-12 CLA. Multiparous Holstein cows (n = 4) were used in a 4 x 4 Latin square design. Treatments consisted of a 5-d abomasal infusion of four doses of trans-10, cis-12 CLA, i.e., 0.0, 3.5, 7.0 and 14.0 g/d. Milk fat yield was decreased 25, 33, and 50%, and milk fat concentration was reduced 24, 37 and 46% when cows received 3.5, 7.0 and 14.0 g/d of trans-10, cia-12 CLA, respectively. Feed intake, milk yield, and milk protein content and yield were unaffected by treatment. Milk fatty acid composition revealed that de novo synthesized fatty acids (short and medium chain) were extensively reduced when cows received the two highest doses, but at the low dose (3.5 g/d), decreases in de novo synthesized fatty acids and preformed fatty acids were similar. Changes in milk fatty acid composition also demonstrated that ag-desaturase activity was inhibited at the two high doses of trans-10, cis-12 CLA, but was unaffected by the low dose. Results indicate minimal quantities of trans-10, cis-12 CLA (0.016% of dietary dry matter) markedly inhibited milk fat synthesis (25% reduction) and that a curvilinear reduction in milk fat yield occurred with increasing quantities of trans-in, cis-12 CLA.