With 2012 being one of, if not the, hottest and driest years in history, concerns over forage nutrition are a forefront topic in the cattle industry.
Producers should be aware of the fact that with dry, dead or dormant forage, the carotene content is reduced in grasses and legumes—which can lead to a Vitamin A deficiency in the herd grazing on those dry pastures.
Eldon Cole, livestock specialist for the University of Missouri Extension Office in Lawrence County Missouri said, “Vitamin A is usually viewed as the most important vitamin regarding the need for supplementation.”
Cole noted that carotene is the precursor to vitamin A and that the best sources of carotene is green, leafy grass or legumes, bright green Alfalfa hay, Alfalfa meal and even yellow corn.
Brian Freking, an agriculture specialist at the Le Flore County Extension Office in Oklahoma said, “Carotene is very low in mature, weathered forages, grains and many crop residues – especially after a drought, and will be lost in stored hay crops over extended periods of time.”
Cole added that, “Naturally in a dry spell like we saw this summer the carotene became pretty scarce with our dry, brown pastures. In the animal the carotene is converted to Vitamin A which can be stored in the liver. After periods of poor grazing those stores of A can be depleted after two or three months.”
Freking said, “Deficiencies of Vitamin A usually show up first as weak, blind or stillborn calves. Other signs are scours, respiratory problems, poor weight gains and poor reproduction rates.” Another common side effect of the deficiency is eye problems such as pinkeye and reduced vision. Vitamin A is involved in bone formation, growth and energy metabolism – especially in calves.
One simple way to correct the deficiency is to provide the cattle with green pastures or bright hay. This may be possible for some producers after the rain we’ve gotten in the past weeks. However, Vitamin A may be added as a supplement as well. This can be done without much cost. It can be in a grain-based feed or even in mineral supplements.
“Perhaps the quickest and least expensive method is to individually inject vitamin A. The cost per cow should run around $1.50 or even less depending on the product used and size of the animal. Some farmers will even give newborn calves a small amount of A at birth as a preventive measure,” said Cole.
Freking agreed, “A singular injection of one million International Units (IU) of vitamin A provides sufficient vitamin for two months to four months in growing and breeding cattle. Depending on the quantity of range supplement being provided, Vitamin A can be added to supplements at the rate of 5,000 to 10,000 IU per pound of feed. Producers should consult their veterinarian about the use of these products and to get specific amounts for the varying needs of the animals in the herd.”


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