A new study in the July Journal of Dairy Science shows that supplementing transition cows with vitamin E decreases the incidence of retained fetal membranes, improves cows’ reproductive performance and provides a slight increase in milk production. Researchers used data from 36 scientific papers that included 53 trials to conduct a comprehensive meta-analysis of the effects of vitamin E supplementation during the transition period. Variables included in the meta-analysis were selenium supplementation, method of vitamin E administration, number of days treated pre- and post-partum and parity and breed of cows.
Results from the meta-analysis confirmed that prepartum vitamin E supplementation increased the blood concentration of vitamin E at parturition, which normally declines by 47% at calving. An analysis of the results by dose showed that the response was linear—the more vitamin E administered the greater the increase in serum vitamin E concentration at calving.
While previous individual research studies have shown a large variation in reproductive performance, the meta-analysis revealed that vitamin E supplementation decreased the risk of retained fetal membranes, reduced the number of services per conception and decreased the number of days open.
In terms of milk production, there was a tendency for vitamin E supplementation to provide a slight increase in daily milk yield. While the average increase was 2.3 lbs of milk per day, the meta-analysis showed that higher doses of vitamin E had a greater effect on milk yield. Results suggest that vitamin E supplementation has a linear effect on both milk production and reproduction. Researchers concluded that transition cows should be fed up to 3,600 IU/day of vitamin E to produce the benefits listed above.