Supplemental Boost

Your cows can get a leg up on production and overall health with ample doses of vitamin E and selenium

As the winter stretches into spring, your stored feeds become depleted of vitamin E - a nutrient vital to your dairy herd's well-being. Supplementing your cows' diets with this vitamin could improve their overall health as they approach calving, as long as you ensure they also get adequate amounts of the mineral selenium in their feed.

Dairy scientists have long established that vitamin E and selenium work together. Research has shown vitamin E can lower the incidence of retained placentas, reduce clinical mastitis and improve milk quality. For maximum effect, however, cows also need enough selenium. For selenium-deficient areas, like much of North America, supplementing this mineral in feed or by injection before calving has been shown to benefit dairy animals.

Why is vitamin E sometimes shorted in herd diets? It is one of the more expensive vitamins to add to a ration.

Vitamin A, by comparison, is often included in mineral packages in vast doses of thousands of international units (ID) per kg. The vitamin E inclusion ranges from the hundreds to single-digit thousands of ID per kg.

Making up this deficit can be worth your while. A recent study showed the positive impact of selenium and vitamin E supplementation during late pregnancy on the reproductive rate and milk production in first-lactation heifers.

Researchers split 60 heifers into three equal groups. The control group received no extra selenium or vitamin E. At four weeks and two weeks before calving, the second group (Tl) received 20 millilitres of selenium, and the third group (T2) was supplemented with 40 mL of selenium and 50 ID of vitamin E.

Selenium concentrations in a cow's blood typically decrease during the final 60 days of gestation. By injecting the heifers with selenium, concentrations increased significantly by calving day, as shown in Table 1.

More colostrum produced

Heifers injected with selenium or selenium and vitamin E also produced more colostrum than the control group. The blood selenium concentration was higher as well.

Vitamin E and selenium also influence milk quality. In this trial, lower somatic cell counts (SCCs) demonstrated better milk quality, and potentially lower mastitis for heifers with more vitamin E and selenium.

Table 2 indicates the Tl and T2 groups had lower SCCs than the control group. Treated heifers had fewer infected quarters at calving, and a lower incidence of sub-clinical mastitis.

Table 1: Selenium concentrations in blood
Selenium concentration
Control T1 (20 mg) T2 (40 mg)
4 Weeks before Calving
Calving Day
Table 2: Milk somatic cell count
Weeks Control T1 (20mg) T2 (40 mg)

Bodies called neutrophils are the first line of defence to fight invading bugs. Selenium-supplemented cows tend to have more active neutrophils. This might explain reduced mastitis in treated heifers.

Eight weeks after calving, the T2 heifers had higher milk production than the control group. While this difference dissipated by week 12, the T2 group's milk production ended up nine per cent higher than that of the control heifers.

Other factors this trial looked at included gestation length, retained placentas, days open and number of services per conception. Neither gestation length nor services per conception differed significantly. However, treated animals experienced fewer retained placentas in this study. As well, days open after calving decreased for treated animals-up to 17 days for the T2 heifers.

In this study, the heifers responded to selenium and vitamin E injections in a variety of ways. Lower disease incidences, higher production and quicker re-breeding were all positive responses.

Ration determines requirement

Your ration will determine the amount of vitamin E your cows require per day. Fresh green forage in high quality pasture may exceed 200 ID per kilogram of dry matter. A dry heifer on pasture may consume 2,000 to 3,000 ID of Vitamin E per day. That same heifer on stored feeds may receive almost negligible amounts without supplementation.

Tom Wright, dairy nutritionist with the Ontario Ministry of Agriculture, Food and Rural Affairs, recommends 0.3 ppm of selenium in the daily diet during the pre-calving and transition period. He suggests 1,200 ID of vitamin E per day for the far-off dry cow, increasing to 2,000 during the transition period.

As this study indicates, supplemental injection could help increase the serum vitamin E and selenium levels in the blood. Research has clearly demonstrated its benefits.


Moeini, M.M, Karami, H., Mikaeili. Animal Reproduction Science 114 (2009) 109-114 Effect of selenium and vitamin E supplementation during the late pregnancy on reproductive indices and milk production in heifers.

This article first appeared in the March 2010 Ruminations column of the Ontario Milk Producer magazine.

Last Reviewed: May 20, 2010

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