Vitamin A deficiency can cause health, reproductive issues in calves, cowherd
“Green grass can solve a lot of issues with vitamin deficiencies, but when we don’t have access or are in a drought situation, it may need to be supplemented,” said Kansas State Clinical Toxicologist Steve Insley.
Insley noted vitamin A deficiencies can be particularly damaging to cattle and are often magnified in poor forage situations.
Following a rough season surrounding vitamin and mineral deficiency, Insley was invited to speak on the subject for Kanas State University’s “Ag Today with Erik Atkinson” radio program.
“Vitamin A is a fat-soluble vitamin stored in the liver of animals,” Insley explained.
“When we look at a death loss, we want to find the issue as soon as we can,” Insley commented. “One of the first places we look is the liver because of the stores of vitamins found there.”
According to University of Missouri (UM), vitamin A is only found in animals but is sourced naturally from plants.
“Plants are the natural source of vitamin A activity for animals,” said UM. “Green and yellow plants contain carotene, a pigment which animals convert to vitamin A.”
UM also noted young animals will have lower body stores of vitamin A and are fed longer than older animals.
“Vitamin A requirements are greater per unit of body weight,” UM said. “The stress of hauling, handling, disease and parasites can also increase requirements.”
Vitamin A deficiency
“Vitamin A deficiency is driven by high nitrates in the forage,” Insley said. “High nitrate levels are driven by drought conditions.”
He explained having late-term pregnancy cows on high-nitrate forages can be difficult. These situations lend themselves to vitamin A deficiencies in calves, which can be a cause of weak-calf syndrome.
“If we have a calf that’s carried to term with a normal birth but still doesn’t want to get up and nurse, we usually look to different neonatal diseases as the cause,” said Insley. “Once we rule out these diseases, we want to start looking into whether a vitamin deficiency as the cause.”
Insley noted some calves might be born completely normal and display no signs of deficiency but can experience complications later in life.
Some common signs of vitamin A deficiency include reduced feed intake and growth, rough hair, night blindness, diarrhea and seizures.
“One of the most notable issues associated with vitamin A deficiencies is night blindness,” Insley said. “Night blindness is most easily determined by putting an obstacle in the path of cattle and watching if they trip over it at twilight.”
Roles of vitamin A
“The chief role of vitamin A is the maintenance of epithelial tissue,” according to UM. “This tissue is found in the skin and lining of the respiratory, digestive and reproductive tract.”
Insley also noted the health of these tissues is vital, especially in cow/calf herds where reproductive health is a top priority.
“Signs of vitamin A deficiency in breeding herds include lowered fertility and calving percentages,” said Insley. “Cows will abort, drop dead or be very weak and difficult to settle.”
According to UM, vitamin A is essential for proper kidney function and the normal development of bones and nerve tissue.
“Vitamin A also functions in visual purple,” UM pointed out. “This compound in the eye is needed for sight when animals adapt from light to dark.”
Fixing vitamin A issues
“We can diagnose deficiencies in both dead and live cattle,” says Insley. “Liver biopsies in live cattle sound a lot more invasive than they really are.”
“Liver biopsies are a non-invasive way to determine the vitamin and mineral status of cattle if we suspect an issue.”
Insley explained if issues arise, the best option for producers is to supplement the vitamin via injection.
“Even though it may not be ideal to work late-term cows, injections are the fastest way to deal with vitamin deficiencies,” said Insley.
“We want to deal with these issues sooner rather than later, so they don’t become fatal,” noted Insley.
Callie Hanson is the assistant editor of the Wyoming Livestock Roundup. Send comments on this article to firstname.lastname@example.org.