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Vitamin and mineral deficiencies: Forages can be part of the problem

Progressive Forage Editor Lynn Jaynes Published on 07 January 2019
beef cows lying in pasture

“Have you ever gone to a company-sponsored producer meeting with one hand over your billfold and one hand over your checkbook, afraid that they [vitamin and mineral supplement companies] would try to squeeze one more dollar out of you?”

The question was posed by Dr. Jeffery Hall, veterinary toxicologist at Utah State University, to a group of cattle producers at the California Cattlemen’s Association Convention in Reno.

Are vitamin and mineral supplement sales profit-driven only? Is it snake oil? Or has something changed in the last 30 years that our cattle need more vitamins and minerals? And what does that have to do with forages?

The underlying problem

Where we’ve been

Hall said vitamin and mineral deficiencies in ruminants “have always been there,” but typically when a producer has a sick animal, they call the veterinarian and ask, “What’s the bug, and what’s the antibiotic to cure it?” Seldom do ranchers send a piece of liver to determine underlying causes, which often include vitamin and mineral deficiencies.

Hall said that from California cattle liver samples, 65 percent that ran through his lab are copper deficient, 64 percent are selenium deficient, and vitamin E and A deficiencies climbed during the drought. He noted several reasons for some of the increases, including producer cost-cutting strategies (especially from 2008 to 2011). As one example of a cost-cutting strategy, producers may buy the cheapest product, which isn’t always a good idea.

Hall said, “Most metal oxides have poor availability, but they’re also the cheapest to buy – you can make up a supplement with high concentrations of these, but that doesn’t mean it’s very available to the animal.”

Management changes

Another reason for increasing deficiencies, Hall said, involves increased production output. A cow produced two calves every three years, just 45 years ago. “We’ve now asked our cow herds to produce 150 percent of weaned calf numbers [a calf every year] that we asked cows 45 years ago to produce – basically with the same groceries,” he said.

Forage challenges

In addition, producers have “altered nature” to calve 30 to 60 days before anything green can grow for grazing, whereas wild ruminants (buffalo and elk, for instance) naturally calve 30 to 60 days after spring greenup, which is the time most efficient to produce the calf, Hall said. And it hasn’t helped any that drought areas have increased in the past decades, creating more nutrient deficiencies in grazed forages.

An additional challenge for producers in the West is that public lands grazing permits often don’t allow turnout until June or later, and ranchers want calves of sufficient size to most efficiently utilize the grazing permits, which rolls calving into earlier months.

The problem with deficiencies

There are several problems associated with vitamin and mineral deficiencies that include poor growth rates, poor immune function (and the subsequent susceptibility to various causes of diarrhea, pneumonia and other diseases) and white muscle disease.

Fat-soluble vitamins require intake of green vegetation. During drought, there is less accumulation of vitamins A and E to sustain a cow through the winter and gestation. If the cow is deficient in vitamins A and E, these vitamins are not passed on to the calf in the colostrum.

Hall said calves should be born with higher concentrations of mineral liver reserves than the cows, because calves are expected to triple their growth in the first 90 days of life. Therefore, what might be a sufficient number for copper levels in an adult animal, for instance, needs to be much more in a calf because of the growing it has to do and the fact it is getting very little from its primary diet (milk).

And for a calf to have those body reserves, the cow has to have sufficient supplies at calving. During the last trimester of gestation, if the cow is deficient in any nutrient, then the immunity of the calf will be compromised, as this is the time she builds antibodies for input into the colostrum.

Deficiencies affect immunity directly and indirectly. An “indirect” effect shows up in not only poor colostrum quality, but also in poor vaccination response. If a vaccine site has a reaction where it significantly swells and goes down over time, Hall said, this can be an indicator of a copper or zinc deficiency. This type of swelling is likely caused by a leaking blood vessel and more reactive mast cells, which happens frequently with copper deficiencies or increase in number and reactivity of mast cells with zinc deficiencies. Calves with vitamin and mineral deficiencies won’t have good reactions in general to vaccinations, and immunity always suffers.

Anticipating and diagnosing deficiencies

Maternal vitamin and mineral deficiencies are associated with repeat breeders, poor conception rates, prolonged calving dates, non-breeders, poor immune function, lameness and poor growth. Hall said if producers rely on a hair coat color change (as in the case of copper deficiency) to diagnose a problem, it’s already too late. When the hair coat actually does change color, the copper level in the liver is almost nonexistent. Anticipating and diagnosing deficiencies must happen much sooner in order for treatment to be effective.

Forage tests

One way to anticipate deficiencies is to test forages. “You need to know what the forages in your area provide,” Hall said. He noted many producers say, “My cattle are on lush green grass – they don’t need supplements.” But the reality, Hall said, is a cow will only get 50 percent of some mineral needs from the grasses.

Liver tests

Liver biopsies can reveal deficiencies and can be performed on live animals. While it’s not practical to biopsy every animal in a herd, if a handful of cows were biopsied and a deficiency was found, it could indicate treatment needs for the larger group.

Hall warned that serum testing is a poor indicator of copper deficiency, because if the results indicate “normal” levels, it doesn’t necessarily mean a problem doesn’t exist.

The payback

A question every rancher asks is, “What’s the return on investment?” as well they should – every dime spent must have an equal or greater return. In answer, Hall noted increased net profits of $50 to $100 per head when deficiencies in vitamins or minerals are corrected.  end mark

Lynn Jaynes
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PHOTO: Cattle graze a late summer pasture near Durango, Colorado. Photo by Lynn Jaynes.

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