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Vitamin E for Dry Cows – Are You Feeding Enough?

7 October 2024

Vitamin E supplementation is absolutely critical for dry dairy cows for immunological function. It also greatly impacts on calf health as well. As vitamin E does not cross the placenta to the developing calf, the calf’s first source of vitamin E is from colostrum.

Nutrient requirements for dairy cows were last reviewed in 2021 by NASEM (National Academies of Sciences, Engineering and Medicine), which replaced the NRC 2001 guidelines, and the recommended level of vitamin E supplementation has greatly increased as shown below:

Table 1. Previous and updated supplementary vitamin E recommendations for dry dairy cows.

NRC 2001NASEM 2001
60 to 21 days pre-calving< 21 days pre-calving60 to 21 days pre-calving< 21 days pre-calving
Vitamin E (IU/day)7407401,1842,220

 

In the last few days before calving, plasma vitamin E levels decline by about 50%, down to levels indicative of chronic deficiency. Part of this is due to colostral transfer but it is also due to the vitamin being used at higher rate as a result of greater immunologic and metabolic stress pre-calving, weakening the animal’s resistance to disease. In fact, cows with low plasma vitamin E pre-calving were nine times more likely to have clinical mastitis compared to cows with acceptable levels (Weiss, 1997).

Vitamin E has a positive effect on neutrophil function – neutrophils are a type of white blood cell and like vitamin E, their function is greatly reduced in the period just before and after calving. This drop in neutrophil function is thought to contribute to the risk of retained placenta, metritis, endometritis and mastitis.

For dry cows, an intake of 1000 units of vitamin E per day is thought to be adequate, but the recommendation increases to just over 2200 units for dry cows in the last 21 days before calving. This higher level helps to combat oxidative stress, which increases significantly around calving time and also helps prevent the natural drop in plasma vitamin E levels close to calving. This higher rate is often recommended for herds experiencing issues with mastitis, metritis or retained placenta.

A dry cow mineral containing 7,000 units of vitamin E per kg, when fed at 150g, will provide 1050 units of vitamin E. The cost of vitamin E will be a key factor in its inclusion in a mineral supplement and it is worth checking the label of mineralised feeds or mineral supplements that are fed to dry cows to find out how much is being supplied at your current feed rate.

lorna.macpherson@sac.co.uk; 07760 990901

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