Effects of various sources of essential fatty acids on performance and glucose metabolism of transition dairy cows

The objective of this study was to compare the effects of diets enriched with two sources of essential fatty acids including n-3 or n-6 fatty acids on performance and glucose metabolism of primiparous and multiparous transition cows. Four weeks before anticipated calving date, 20 multiparous and 12 primiparous cows were blocked by parity and randomly allotted to two diets based on n-3 or n-6 fatty acids. Feed intake and serum glucose concentration were greater in cows fed diets enriched with n-3 fatty acids than n-6 fatty acids (P < 0.05), at pre- and postpartum periods. Multiparous, but not primiparous, cows supplemented with n-3 fatty acids had greater DMI (as percentage of BW) and milk lactose concentration, improved energy balance and lower beta-hydroxybutyrate (P < 0.05) than cows fed n-6 enriched diets. Results of glucose tolerance test showed that area under the curve of glucose following glucose infusion was lower for multiparous cows fed n-3 enriched diets compared to those fed n-6 enriched diet (P = 0.01), but this response was not observed in primiparous cows. In conclusion, supplementation of n-3 fatty acids in transition period increased DM and energy intakes and shifted this energy toward inhibiting body reserves mobilization, possibly due to improved insulin responsiveness in response to feeding n-3 enriched diets, especially in multiparous cows.