Cattle producers in states impacted by drought need to be aware that these conditions can potentially cause vitamin A deficiencies in their animals.
Vitamin A is rarely a concern in range cattle nutritional programs because it is readily synthesized from carotene that is common in green growing plants. However, in drought situations where plants become dead or dormant, the carotene content becomes practically devoid and may lead to a deficiency of the precursor to vitamin A.
"Carotene is very low in mature, weathered forages, grains and many crop residues, and will be lost in stored hay crops over extended periods of time," said Glenn Selk, Oklahoma State University Cooperative Extension emeritus livestock specialist. "If hay that was stored throughout all of last fall and winter is to be fed in the upcoming winter, the vitamin A content will be considerably less than when that forage was originally harvested."
In addition, some scientists have suggested that high nitrate forages common in drought years can exaggerate vitamin A deficiencies.
"Deficiencies of vitamin A usually show up first as weak, blind or stillborn calves," Selk said. "Other signs are scours, respiratory problems, poor gains and poor reproduction."