Vitamin A is the vitamin most likely to be deficient in beef cow diets this winter. Vitamin A is not present in plant material, but its precursors, also known as carotenoids, such as beta-carotene, are present in high amounts in leafy green forage. Beta-carotene is converted to vitamin A mainly in the cow’s small intestine.
During a grazing season with normal precipitation daily intake of beta-carotene may be three to five times the animal’s requirement and excess vitamin A can be stored in the liver.
During drought, beta-carotene in growing forage is inadequate to meet requirements, limiting liver stores. Vitamin A can be provided through dry or liquid supplements, mixed feeds or mineral supplements in case needed to avoid consequences of Vitamin A deficiency (reduced growth, low conception rates, abortion, stillbirths, and weak calves).