Trace mineral deficiencies of copper and selenium are endemic in the U.S. cow herd, but the problem is most obvious in calves. But if you see the signs of deficiencies in your calves, that means your cows need attention.
Dr. Jeff Hall of Utah State University, speaking at the Cattlemen’s College during the recent National Cattlemen’s Beef Association annual conference, explained the dynamics of mineral needs in calves. Since the calf gets almost all of its nutrition from milk in the first 90 days of life, it must be born with sufficient body reserves of trace minerals.
“Calves have to be born with higher body reserves than an adult animal,” he explained. Using the example of copper concentrations in the liver, he explained to his audience that 25-100 parts per million [ppm] of copper is normal for an adult animal.
“If I test a 2-day-old calf and it’s less than 65, I’m going to call it deficient. Is it clinically deficient? No, but it has inadequate body reserves,” he went on. “If it’s not born with at least 65 [ppm copper], it will be clinically deficient. But that also tells me that mama ran out. The only way a calf is born without sufficient body reserves is because mama ran out, because she’ll deplete her own system to make sure that calf has enough.”
Hall explained that in the last trimester of pregnancy, and especially in the last 30 days, a cow’s body will move minerals from her own supplies into the fetus. Though he acknowledged that this information is not always well received, he asserted that a mineral deficient calf is a sign that its dam is deficient.
“Every time we’ve done liver biopsies on cows of a calf that we found that was low, 100 percent of the time that cow was deficient. She ran out. That is the only way a calf will be born without enough body reserves.”
He also told his audience that higher levels of open young cows are also often indicative of mineral deficiencies.
“They have a higher dietary requirement for minerals because they are moving mineral to the fetus, they have mineral needs for maintenance, and they are still growing. So oftentimes you’ll see an increased amount of opens in these younger animals if you’re in a marginal mineral status because your more mature cows don’t have as much demand because they’re not growing. They have that slight advantage of not needing quite as much mineral in their diet to get by.”
Hall stressed the value of mineral supplementation to the cow herd, particularly during later pregnancy. Some attendees asked about the economic impact of supplementing calves, but he advised:
“Most of the time, you’re more money ahead getting [a supplement] into mama during that last trimester of gestation and allowing her to process it so that the calf is born with the mineral in a functional form.” — Kerry Halladay, WLJ editor
