“Pre-fresh cows should be the highest priority and be maintained at National Research Council (NRC) levels for vitamin A and probably 2,000 international units (IU)/day for vitamin E,” Weiss says. The recommendation for Vitamin A is 50 IU/lb of body weight, so for Jerseys that translates into 50,000 IU/day and for Holsteins, 70,000 IU/day. A pre-fresh period of two to three weeks should be adequate, says Weiss.
He notes that several studies have shown Vitamins A and E reduce mastitis, abortion, retained placentas and metritis. “Substantial amounts of those vitamins are put into colostrum and substantial amounts of those vitamins are metabolized during the process of [birth],” he says. Weiss notes that if you do not have a separate pre-fresh group for dry cows, the priority is to supplement at these levels for all dry cows.
“I would try to provide some supplemental Vitamins A and E to all cows, but lactating cows would be the lowest priority,” he says. “These cows consume a lot of feed and the feed is usually better than that fed to dry cows…. If vitamin A becomes scarce, I think you can reduce vitamin A supplementation to about 50% for several months. Likewise, vitamin E supplementation to lactating cows could probably be cut to 50% of NRC in the short term (a few months).”