Short communication : Associations between blood fatty acids, β-hydroxybutyrate, and α-tocopherol in the periparturient period in dairy cows : an observational study

The objective of the present study was to examine the relationships between blood concentrations of fatty acids, \u3b2-hydroxybutyrate (BHB), and \u3b1-tocopherol during the periparturient period in dairy cows. Blood samples were collected from 131 cows belonging to 4 different commercial dairy farms in southeastern Europe (Greece and Italy). We determined blood concentrations of fatty acids, BHB, and \u3b1-tocopherol at dry-off, at calving, and 30 d postpartum. Results indicated that fatty acid concentrations were low at dry-off, reached maximum value at calving, and then declined at 30 d postpartum. In fact, fatty acid concentrations at 30 d postpartum were 50% lower than at calving. In contrast, BHB concentrations were low at dry-off, increased by 27% at calving, and continued to increase by another 20% at 30 d postpartum. Overall, we found a weak correlation between fatty acids and BHB throughout the periparturient period. Concentrations of \u3b1-tocopherol were lowest at calving, and we detected no differences in \u3b1-tocopherol concentrations at dry-off or 30 d postpartum. Negative correlations between fatty acids and \u3b1-tocopherol were highly significant at 30 d postpartum and approached the level of significance at dry-off. However, both correlations became nonsignificant following the adjustment of \u3b1-tocopherol with cholesterol, indicating that the correlations were a reflection of changes in lipid transport. We found significant negative correlations (strong at dry-off and weak at 30 d postpartum) between BHB and \u3b1-tocopherol after adjustment with cholesterol. The physiological basis for the negative correlations between BHB and \u3b1-tocopherol, especially that at dry-off, is not known and should not be taken to imply a cause-effect relationship. However, it opens the door to investigating the effects of vitamin E on liver function in dairy cows