Newborn beef calves are the most vulnerable to vitamin A deficiency, and current recommendations may not be adequate
An invited review in Applied Animal Science re-examines the evidence behind beef cow vitamin A requirements and calls for more research and updated supplementation strategies
Champaign, IL, May 26, 2026—Beef calves are born with very little vitamin A--a crucial micronutrient for health, reproduction, and growth--stored in their bodies and depend almost entirely on colostrum to build the reserves they need for a healthy start. Yet, the supplementation guidelines producers rely on to ensure their cows deliver vitamin-A-rich colostrum are based on a handful of studies from the mid-1900s, many of which used small numbers of animals, variable forms of vitamin A, and genetics that look nothing like today’s cattle. A newly published invited review in Applied Animal Science takes a close look at what we know, and what we don’t, about vitamin A in beef cow-calf systems and makes the case that current recommendations need to be updated to meet modern standards for calf health and economic success.
“What makes vitamin A tricky in cow-calf systems is that a cow can look perfectly healthy and carry a pregnancy to term while her calf is born without enough vitamin A to fight off basic infections because very little of it is transferred through the placenta,” explained lead author Mary Drewnoski, PhD, of the University of Nebraska-Lincoln, USA. “The cow’s own needs for health and pregnancy are relatively low, so by the time you see a problem, it’s usually the calf--not the cow--that’s affected with respiratory disease, diarrhea, reduced growth, and vision losses.”
The invited review synthesizes decades of research on vitamin A biology, metabolism, and supplementation as it applies to cow-calf production. The authors trace the original, foundational studies from the 1930s through the 1970s that form the basis of the current recommendation of 60 international units of supplemental vitamin A per kilogram of body weight for gestating beef cows. They identify key limitations of that evidence base, including small sample sizes, outdated genetics, and the use of beta-carotene--which can be converted into retinol, the active form of vitamin A--rather than preformed vitamin A in many of the foundational trials.
A central theme of the review is the importance of colostrum as the primary delivery vehicle for vitamin A to the newborn calf. Because very little vitamin A crosses the placenta, calves are born with minimal liver stores and depend on the timely intake of colostrum rich in retinol. The authors note that both the dam’s liver reserves and her dietary vitamin A intake during late gestation contribute to colostral retinol concentration, but research suggests that dietary intake in the weeks before calving may play the larger role in enriching colostrum for the calf.
Caption: Neonatal beef calves are highly dependent on maternal vitamin A transfer and are at greatest risk of deficiency in cow-calf systems where cows rely on stored or dormant forages during late gestation (Credit: Marissa Eekhoff).
“For producers who calve in late winter or early spring, the timing is especially challenging,” said Drewnoski. “Cows are often eating stored forages that have lost much of their beta-carotene during harvest and storage. Hay that looked green going into the barn can lose the majority of its vitamin A value within a few months. That means the cow’s diet alone may not provide enough vitamin A to build up her colostrum at exactly the time it matters most.”
Bill Weiss, PhD, PAS, Dipl. ACAS, editor in chief of Applied Animal Science, commented on the invited review. “Recent research on vitamin A in beef cow-calf systems is extremely limited, even though the young calf is most likely to be low in vitamin A. This review examines available data and makes recommendations that emphasize calf health rather than just that of the cow.”
The authors conclude that although vitamin A is one of the more costly micronutrients to supplement, the consequences of under-supplementation for calf health, including respiratory disease, diarrhea, vision loss, and reduced growth, can be far more costly. They call for new research to determine how much vitamin A gestating cows truly need to ensure their calves start life with adequate stores, as well as studies that account for the highly variable beta-carotene content of stored forages, interactions with other nutrients like zinc and protein, and the realities of on-farm supplement storage.
The article appears in the June 2026 issue of Applied Animal Science.
Notes for editors
“Invited Review: Vitamin A in beef cow-calf systems--Biological relevance, revisiting of requirements, and unresolved questions,” by M. K. Eekhoff, S. L. Hansen, and M. E. Drewnoski (https://doi.org/10.15232/aas.2025-02772), Applied Animal Science, volume 42, issue 3 (June 2026), published by FASS and Elsevier.
This article is openly available at https://doi.org/10.15232/aas.2025-02772.
To schedule an interview with the author(s), please contact Mary Drewnoski, PhD, at mary.drewnoski@unl.edu.
About Applied Animal Science
Applied Animal Science (AAS) is a gold open access, peer-reviewed scientific journal and the official publication of the American Registry of Professional Animal Scientists (ARPAS). In continuous publication since 1985, AAS is a leading outlet for animal science research. It has a Journal Impact Factor and is indexed by Scopus, Clarivate, CABI, and AGRICOLA. AAS caters to a wide and comprehensive audience, and its readers are typically university, extension, animal-industry, and government employees; members of professional societies and related organizations; producers, commodity organizations, and related feed and foods industries; researchers and students; and consultants and companies providing products and services in animal agriculture. The journal welcomes novel manuscripts on applied technology, reviews on the use or application of research-based information on animal agriculture, commentaries on contemporary issues, short communications, and technical notes. Topics that will be considered for publication include (but are not limited to) feed science, farm animal management and production, dairy science, meat science, animal nutrition, reproduction, animal physiology and behavior, disease control and prevention, microbiology, agricultural economics, and environmental issues related to agriculture. Themed special issues also will be considered for publication. www.appliedanimalscience.org
About the American Registry of Professional Animal Scientists (ARPAS)
The American Registry of Professional Animal Scientists (ARPAS) is the organization that provides certification of animal scientists through examination, continuing education, and commitment to a code of ethics. Continual improvement of individual members is catalyzed through publications (including the AAS journal) and by providing information on educational opportunities. ARPAS is affiliated with five professional societies: American Dairy Science Association, American Meat Science Association, American Society of Animal Science, Equine Science Society, and Poultry Science Association. www.arpas.org
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