The effect of co-supplementation of fish oil and vitamin E on reproductive performance and metabolic profile during the transitional period in dairy cows

Abstract

The objective of the present study was to determine the effect of oral supplementation of dairy cows with a combination of fish oil and vitamin E (Vit E) from approximately 7 days (d) before the expected calving date up to 21 days postpartum, on their reproductive performance and metabolic profile. Eighty Holstein multiparous cows were randomly assigned into one of two ration groups during the transitional period. The treatment group cows (n=40) received a transitional diet (pre-and post-partum based on the NRC 2001) supplemented with fish oil (FO, 100 g/ once per day +Vit E (8000IU/kg/d); and the control cows (n=40) received the same concentrate without FO. Blood samples were collected at 1 week before the expected calving date, and 1, 2 and 3 weeks postpartum. After a voluntary waiting period, all cows received timed artificial insemination (TAI) at 76-81 days in milk (DIM) following the PresynchOvSynch protocol. Pregnancy diagnosis was performed 30-40 days after TAI using a transrectal ultrasonography. Our results showed that the cows fed the FO+Vit E diet had a statistically higher first service pregnancy rate (46.3 % vs. 39.6%, P<0.001) at 30-40 days after TAI than those fed the control diet. Also, cows that consumed the FO+Vit E treatment diet had lower late embryo loss at 40-70 days post insemination than the control. Plasma concentrations of triglycerides (d7, 14, and 21), cholesterol (d7 and 14), glucose (d14), insulin (d-7) progesterone (d14 and 21) in the treatment group were higher (P<0.05) compared to the cows fed control diets. Non-esterified fatty acid (NEFA) levels were not significantly affected by the dietary treatments pre-partum, while β –hydroxybutirate acids (BHBA) levels on day 21 (P<0.05) were higher in the control group. The results indicated that supplementation of the diet with fatty acid and high doses of vitamin E could improve reproductive performance in dairy cattle.