Conjugated linoleic acids alter milk fatty acid composition and inhibit milk fat secretion in dairy cows
Conjugated linoleic acids alter milk fatty acid composition and inhibit milk fat secretion in dairy cows
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DOI：
10.1093/jn/129.8.1579
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发表时间：
1999-08-01
影响因子：
4.2
通讯作者：
Bauman, DE
中科院分区：
文献类型：
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作者：
Chouinard, PY;Corneau, L;Bauman, DE
共轭亚油酸（CLA）在实验模型中具有积极的保健作用。我们的目的是确定添加CLA对奶牛产奶量的影响。将商业来源的CLA以皱胃方式注入以绕过瘤胃发酵。CLA含量为61.2%；CLA的主要异构体为顺式/反式8、10、顺式/反式9、11、顺式/反式10、12和顺式/反式11、13。四头荷斯坦奶牛采用4 × 4拉丁方形设计。各组分别输注0、50、100、150 g/d的CLA。注射使乳脂含量从6.8 mg/g脂肪（零剂量）增加到63.6 mg/g脂肪（最高剂量）。补充剂中所有主要的CLA异构体都以剂量依赖的方式转移到乳脂中。顺式/反式8、10、顺式/反式9、11、顺式/反式10、12和顺式/反式11、13对乳脂的表观转化效率分别为22.5%、22.5%、10.2%和26.3%。CLA输注对乳蛋白无影响，对产奶量影响较小（添加0、50、100和150 g/d CLA分别为21.5、20.4、20.9和18.3 kg/d）。然而，CLA输注显著减少乳脂。乳脂含量和产量平均分别降低52%和55%。具体的CLA异构体的作用和减少乳脂的机制尚未确定，尽管牛奶脂肪酸的模式在脂肪酸合成和去饱和过程中表现出最明显的影响。综上所述，饲粮中添加CLA提高了乳脂含量，改变了乳脂肪酸组成，显著降低了乳脂含量和产量。
Conjugated linoleic acids (CLA) have positive health effects in experimental models. Our objective was to determine the effect of CLA supplementation on milk of dairy cows. A commercial source of CLA was infused abomasally to by-pass rumen fermentation. The supplement contained 61.2% CLA; the major CLA isomers were cis/trans 8,10, cis/trans 9,11, cis/trans 10,12 and cis/trans 11,13. Four Holstein cows were used in a 4 x 4 Latin square design. Treatments were 5-d infusions of 0, 50, 100 and 150 g/d of CLA supplement. Infusion increased milk fat content of CLA from 6.8 mg/g fat (zero dose) to 63.6 mg/g fat (highest dose). All of the major CLA isomers in the supplement were transferred to milk fat in a dose-dependent manner. Apparent efficiency of transfer to milk fat was 22.5, 22.5, 10.2 and 26.3% for cis/trans 8,10, cis/trans 9,11, cis/trans 10,12 and cis/trans 11,13, respectively. CLA infusion had no effect on milk protein and little effect on milk yield (21.5, 20.4, 20.9 and 18.3 kg/d for 0, 50, 100 and 150 g/d CLA supplement, respectively). However, CLA infusion dramatically reduced milk fat. On average, the content and yield of milk fat were reduced by 52 and 55%, respectively. The role of specific CLA isomers and mechanism(s) for the reduction in milk fat have not been established, although the pattern of milk fatty acids demonstrated effects were most pronounced on de novo fatty acid synthesis and the desaturation process. Overall, dietary supplemention of CLA increased milk fat content of CLA, altered mirk fatty acid composition and markedly reduced the content and yield of milk fat.