Recommended vitamin E level for cows too low
VITAMIN E recommendations for dairy cow diets are too low to realise possible benefits of reduced mastitis and improved fertility, according to researchers at ADAS Bridgets, Hants.
After a literature review, reported in the Vet Record, Dec 16, Richard Allison and Richard Laven conclude that the recommendation for feeding 15mg/kg of dry matter of feed appears inadequate.
They also advise that tying the rate of inclusion to dry matter fails to allow for the cows increased need for vitamin E during the dry period, when feed intakes are low.
Research papers conclude that vitamin E has a beneficial effect on the immune system where rates four times that currently recommended are fed, they add.
This is mostly seen in reduced mastitis incidence or duration of clinical disease in early lactation, when at least 1000iu of vitamin E is fed during the dry period and early lactation. These results can even be seen in studies where a control group of cows has received three times the recommended rate of vitamin E.
The effect of vitamin E on fertility is less pronounced, say the reports authors. In selenium deficient cows, incidence of retained placenta was reduced when vitamin E levels were increased, say Dr Allison and Dr Laven.
Some research, using small numbers of cows, also shows a reduction in cystic ovarian disease and metritis. But studies are small and many other studies show no benefit through additional supplementation. *