Vitamin A Deficiency in Cattle: Night Blindness, Immune Failure, and Reproductive Loss

Vitamin A deficiency in cattle causes progressive vision impairment, immune compromise, reproductive failure, and nervous system damage, with significant welfare implications in high-risk production systems.

Key Facts

Vitamin A is essential for vision, immune function, epithelial integrity, reproduction, and neural development in cattle; it cannot be synthesized and must be obtained from diet.
Deficiency is most common in cattle fed dry forages for extended periods, in drought-affected herds, in animals on high-grain finishing diets, and in calves born to deficient cows.
Night blindness (nyctalopia) is often the first clinical sign, followed by daytime vision impairment, lacrimation, and in severe cases, complete blindness.
Convulsions and nervous system signs occur when cerebrospinal fluid pressure rises from deficiency-impaired cerebrospinal drainage — an emergency welfare condition.
Reproductive impacts include early embryonic death, abortion, stillbirths, and birth of blind, weak, or malformed calves.
Dietary sources include fresh green forage, silage, and vitamin A supplements; beta-carotene in green forage is converted to vitamin A in the gut.
Injectable vitamin A supplementation provides rapid restoration of body stores; prevention through supplementation is straightforward and inexpensive relative to the welfare and production costs of deficiency.

Welfare Considerations

Vitamin A deficiency causes progressive welfare compromise that affects sight, neurological function, and immunity. Cattle with night blindness navigate poorly in low light, are more prone to injury, and show behavioral indicators of anxiety in dim conditions. Progressive daytime vision impairment reduces the ability to find food and water, engage in social navigation, and identify threats. The neurological crises caused by elevated cerebrospinal fluid pressure — fitting, head pressing, circling, and collapse — are acutely distressing episodes superimposed on chronic deficiency. Calves born to deficient mothers may be blind at birth, with all the attendant welfare implications of congenital blindness. The complete preventability of vitamin A deficiency through appropriate supplementation in at-risk cattle makes this condition a clear priority for welfare-focused nutrition management.

What You Can Do

Implement vitamin A supplementation programs for cattle on extended dry forage or high-grain diets.
Monitor for early signs of vitamin A deficiency: night blindness, lacrimation, and poor coat condition in at-risk groups.
Ensure cows receive adequate vitamin A during late pregnancy to prevent deficiency in newborn calves.
Work with a veterinary nutritionist to assess vitamin A status and supplementation requirements for your herd.
Learn about the relationship between diet quality, trace mineral status, and the welfare of beef and dairy cattle.