Most of Texas is currently under drought conditions, much of them severe. And this condition has persisted for a long time in some areas. One thing that comes into play during drought that is usually not a problem is Vitamin A deficiency. Cattle can store from two to four months supply of vitamin A in the liver on diets exceeding Vitamin A requirements, basically a little something green. That supply can be exhausted in a drought. How do you supply supplemental vitamin A? My colleague Dr. Ted McCollum, Extension Beef Cattle Specialist at the Texas AgriLife Center in Amarillo, recently summarized supplementation of vitamin A:
- most fortified range/breeder cubes fed at 1-1 1/2 lb/day for dry cows or 1 1/2 - 2 lb/day for lactating cows should provide adequate levels of vitamin A;
- mineral supplements, if fortified with 200,000 units vitamin A/lb, would provide adequate levels when consumed at rates of 2-4 oz/day;
- stability of vitamin A in supplements can be affected by composition of the supplement, source of vitamin A, and length and conditions of storage;
- injectable vitamin A can be used to provide from about 1-3 months reserve, depending on the cow’s stage of production and the concentration and dose of the product.
