Supplementation with Selenium and Vitamin E Improves Milk Fat Depression and Fatty Acid Composition in Dairy Cows Fed Fat Diet

This experiment was conducted to evaluate the effect of supplementing a fat diet with selenium (Se) and vitamin E on performance of cows, blood antioxidant status and milk fatty acid composition. Sixty-three lactating Holstein cows were randomly divided into seven groups of nine cows each and each group was fed one of the following diets: i) a basal diet (control); ii) a basal diet with 0.15 mg Se/kg DM (LSe); iii) a basal diet with 0.3 mg Se/kg DM (HSe); iv) a basal diet with 5,000 IU/cow d vitamin E (LVE); v) a basal diet with 10,000 IU/cow d vitamin E (HVE); vi) a basal diet with 0.15 mg Se/kg DM and 5,000 IU/cow d vitamin E (LSeVE); vii) a basal diet with 0.3 mg Se/kg DM and 10,000 IU/cow d vitamin E (HSeVE). Milk fat percentage and conjugated linoleic acid (CLA) yield in HVE and HSeVE diets increased (p<0.05) compared with the control diet. In milk fat, dietary supplementation of Se tended to increase the proportion of the sum of unsaturated fatty acids (UFA) and significantly decreased (p<0.05) the proportion of the sum of saturated fatty acids (SFA). In addition, compared with the control, thiobarbituric acid reactive substances (TBARS) content was lower and glutathione peroxidase (GSH-Px) was higher when fat diets were supplemented with Se. Our data showed that supplementation with Se and/or VE improved these nutrients in blood and milk. The results indicated that fat diets supplemented with Se improved both antioxidant status in blood and fatty acids in milk fat, and fat diets supplemented with vitamin E alleviated milk fat depression. Therefore, the combination of Se and vitamin E caused synergistic effects on the nutritional quality of milk fat and performance of cows fed a fat diet.