An excellent article on minerals for the cowherd was published in the January 2012 issue of the Bovine Veterinarian. The author was Luke Miller, M.S., a ruminant nutritionist with Great Plains Livestock Consulting, Inc. in Eagle, NE. Miller stated that mineral and vitamin supplementation is a concern when it gets close to calving and the subsequent breeding season, as these factors are vital for fetal development, growth, immunity and other metabolic factors. Some of his observations and recommendations follow.

Calcium is crucial for smooth muscle function, and its lack can cause calving difficulty, retained placentas and prolapses. A cow’s calcium requirements increase by 22% from mid to late gestation and another 40% after calving.

Phosphorus in combination with calcium is necessary for bone and tissue development and for milk production, as some forages are high in phosphorus. Miller says that a mineral containing 3 to 6% phosphorus is sufficient for cows not getting any by-product feeds.

As copper, zinc and selenium are needed in enzymes involved in metabolism of energy and protein, he recommends using chelated minerals in breeder minerals and also when weaning or receiving high-risk cattle. He points out that since copper and zinc are absorbed at the same location in the small intestine, over supplementation of one can cause an antagonistic effect of the other, resulting in a deficiency.

Weak, unthrifty and blind calves are often a sign of Vitamin A deficiency during gestation. If Vitamin E along with selenium are deficient, calves may suffer from white muscle disease, weak calves and impaired suckling ability caused by poor development of tongue muscles.

I was impressed by Miller’s concise evaluation of a complex situation but would like to add a couple of observations.