Vitamin E: What's the Requirement?
Dec 30, 2013
Inconclusive research leads to expensive guessing.
Vitamin E can be one of the most expensive supplements in our rations, and in my opinion, we don’t know the cow’s requirement.
Vitamin E is an antioxidant and is supplemented to reduce oxidative stress in tissues caused when reactive oxygen species (ROS) accumulate. These ROS have been shown to be associated with an increased incidence of retained placenta and metabolic diseases. The National Research Council (NRC) recommends supplementing 1000 IU of vitamin E prepartum and 500 IU postpartum. Researchers at Ohio State have suggested that levels as high as 4,000 IU prepartum may be beneficial.
So, what does this cost the dairy producer? Vitamin E production is controlled by very few players in the world – primarily the Chinese. The market goes up and down as these producers manipulate the market. The approximate cost for 1000 IU of vitamin E, by the time it gets to the farm has varied over the past 6 years from as low as 3¢/cow/day to over 10¢/cow/day. So, 4000 IU could cost as much as 40¢/cow.
There have been no definitive titration studies done with vitamin E under different physiological or environmental conditions to really pinpoint a requirement. We went from 300 IU to 500 to 1000 and then jumped to 4,000 IU as recommended supplemental levels. What if you’re feeding fresh forage, which can be loaded with vitamin E, or only ensiled forages with very little vitamin E?
I recently read a University of Florida study, where the effect of heat stress and vitamin E levels were examined. The hypothesis was that heat stress increased oxidative stress in the animals and vitamin E may help alleviate this. Cows were supplemented with levels from 500 to 3000 IU vitamin E pre and postpartum under cooled or heat stressed conditions.
The results were pretty much inconclusive, although feeding more vitamin E did increase the level of E in the blood. Feeding the high level of vitamin E to mature cows under heat stress increased milk, but first-calf heifers actually produced less milk with higher vitamin E supplementation, whether heat stressed or not. Based on blood NEFA levels, the first-calf heifers were under less metabolic stress than cows. The researchers theorized that supplementing too much vitamin E to the less stressed heifers may have caused greater radical formation which reduced performance. Wow, too much vitamin E?
There’s no question that vitamin E is a required nutrient. Dairy producers spend a lot of money on vitamin E, based on what I consider less than adequate research.
We’ve really dialed in on protein and carbohydrate requirements in recent years. I think we should do the same with vitamin E. Since the U.S. doesn’t produce any, maybe we could make it a national security issue.
Lundquist & Associates, Nutrition Professionals, is based in Duluth, MN. Contact Rick at firstname.lastname@example.org.