STILLWATER, Okla. – Cattle producers in Oklahoma and other Southern Plains states need to be aware that drought 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.”

Fortunately, the liver of cattle is capable of storing vitamin A for long periods and frequent supplementation is not necessary. 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.

“It is important to remember that vitamin A and A,D and E injections have been found – on very rare occasions – to cause a severe reaction to the vaccine,” Selk said. “Producers should consult their veterinarian about the use of these products.”

Because the daily requirements of beef cows range from 30,000 to 50,000 IU, depending on size, stage of production and level of milk production, supplements can be fortified with vitamin A to supply the minimum daily requirement.

“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,” Selk said.

Anyone interested in obtaining additional information about vitamin and mineral needs for grazing cattle should consult the Oklahoma Cooperative Extension Service circular E-861, “Vitamin and Mineral Nutrition of Grazing Cattle,” available through all OSU Cooperative Extension county offices or at via the Internet.


Donald Stotts
Communications Specialist
Agricultural Communications Services
143 Agriculture North
Oklahoma State University
Stillwater, OK 74078
Phone: 405-744-4079
Fax: 405-744-5739
Email: [email protected]

Oklahoma State University, U. S. Department of Agriculture, State and Local governments cooperating; Oklahoma State University in compliance with Title VI and VII of the Civil Rights Act of 1964, Executive Order 11246 as amended, Title IX of the Education Amendments of 1972, Americans with Disabilities Act of 1990, and other federal and state laws and regulations, does not discriminate on the basis of race, color, national origin, gender, age, religion, disability, or status as a veteran in any of its policies, practices, or procedures, and is an equal opportunity employer.


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