Have you heard from your veterinarian about Vitamin A deficiencies, or the likelihood of them this year? Vitamin A deficiency can present with many different clinical signs, but the most common signs are weak or stillborn calves. In this article published by Dr. Gregg Hanzlicek of Kansas State University, he will discuss some possible reasons why this may occur in spring-calving beef herds.
Fresh, green forages contain very high levels of Vitamin A (as carotenes). It is rare for Vitamin A deficiency to occur during a normal pasture season. We do occasionally observe deficiencies in the pasture season during drought conditions. As the grasses become dormant (have turned from green to brown color), the Vitamin A content will decrease and the pasture may not provide the appropriate amount of required dietary vitamin.
Vitamin A deficiency is primarily a winter issue. Cows on green-grass pastures will store Vitamin A in their liver. During late fall and winter, when Vitamin A intake is not sufficient, they can use this storage supply to meet metabolic demands. Unfortunately, the storage supply only lasts between 2 and 4 months.