Some vitamin and mineral deficiencies in cattle can be obvious. But many aren’t, and the producer can address the problem with some well-applied knowledge.
Dr. Shane Gadberry, professor of ruminant nutrition for University of Arkansas Extension, said an acute deficiency can result in obvious production loss.
“For example, we might see an issue with selenium and/or Vitamin E in calves that are born weak; a post-mortem exam by the veterinarian may reveal what we call ‘white-muscle disease,”’ Gadberry told Ozarks Farm & Neighbor. “There can also be what we would call sub-acute cases where production is being impacted, but we don’t have losses to the point that it is easily identifiable; it might be subtle reductions in growth rates, and those are a little harder to determine because most of the time we don’t have something to compare that growth rate against.”
If cows receive a complete mineral supplement, vitamin deficiencies can be rare. Complete supplements are well fortified with fat-soluble vitamins A, D and E. However, if cows only get a trace mineralized block or a plain white salt block, it may result in a vitamin A deficiency in the herd. Gadberry said sun-cured forages don’t have the keratin load of green forages; since Arkansas producers typically feed hay 3 to 4 months out of the year – in some cases, longer – that is the period where cows may lack Vitamin A.
“The liver does a good job of storing vitamin A for a few months,” he explained. “But unfortunately many times, especially following a drought–and we know that we’ve had a very dry fall – many of our cattle producers in Arkansas may find themselves feeding hay for 4 to 6 months within a given year.”
A Vitamin A deficiency leads to suppressed immunity, suppressed growth rates, rough hair coats, and even a poor conception rate.
Put-up hay will also have reduced amounts of Vitamin E compared to green forages, but here Gadberry said the literature is unclear.
“Science has yet to do a really good job of defining what the exact requirements of vitamin E nutrition in the cow herd are for optimal production,” he said. “We do know that there are areas that are inadequate in selenium, and we see selenium deficiencies in Arkansas; selenium and vitamin E work closely together in the body, so a lot of the vitamin E deficiencies are tied to the same symptomology that we see in a selenium deficiency. With vitamin E we can have calves that are born weak, buckling of the feet in feeder calves and retained placentas with our mature cow herd.”
Dr. Patrick Davis, University of Missouri Extension regional livestock specialist, said if cows are deficient in vitamins A and E, that will inhibit transfer to newborn calves through colostrum. “This could cause these calves to have diarrhea, pneumonia and weak calf syndrome,” Davis told OFN. “The way to prevent against this is to make sure cows are on a vitamin/mineral supplement that meets their requirements, so that vitamins and minerals are passed onto their calves through the placenta and colostrum.”
If the nutrient requirements are met prior to calving and the cow is in good body condition score, the producer normally will not see any signs of nutrient deficiency in calves. In a drought year there is potential for a vitamin A deficiency, which can cause newborn calves to be born weak and blind.
Davis explained, “There is improper osteal growth leading to pinching of the optic nerve at the point where it passes through the optic chiasma.”
