Minerals could be at the root of your herd health problems. “The symptoms of deficiencies in trace minerals are often subtle,” says Twig Marston, beef Extension specialist with Kansas State University.
“With deficiencies in selenium, for instance, there are more retained placentas at calving and a slight decrease in breeding soundness exams,” he says. “Both copper and zinc deficiencies might cause a drop in pregnancy rates.”
Geography and ongoing changes in weather and growing conditions can make trace mineral deficiencies a permanent or sporadic adversary.
“Soil conditions, rainfall, plant growth, and proximity to water all have an effect,” says Marston. “There are areas of Kansas, for instance, that have a high molybdenum content in forages and grains that decreases the availability of copper.”
And in many parts of Montana, South Dakota, Wyoming, and North Dakota, high-sulfate water can tie up the availability of copper and selenium, says Cody Wright, Extension beef specialist at South Dakota State University.
Wright has a seven-step strategy for addressing mineral deficiencies.
1. Study Herd Performance
Because individual deficiencies can share common symptoms, it's hard to diagnose a specific deficiency based on a single symptom. The first step in detecting and addressing a possible mineral deficiency is to look at herd-performance parameters, like reproductive rates and weaning weights. Compare these to historical or standardized performance data.
2. Analyze Feed, Water, Current Supplements
This is a follow-up step only if shortfalls in herd performance suggest possible deficiencies.
The laboratory screenings typically measure the macro minerals: calcium, phosphorus, magnesium, potassium, and sulfur. They also may include the trace minerals: cobalt, copper, zinc, selenium, manganese, iodine, and iron.
“In some cases, a little bit of testing might result in savings,” says Wright. “I know of two producers who feed no supplement other than white salt because they tested to learn about the mineral content of their feeds. But that's not going to work for everybody. There are many situations where forages don't meet all the mineral needs of cattle.”
For confusing cases, blood samples or liver biopsies can confirm the presence or absence of mineral deficiencies. Those might be needed when feed analyses show sufficient mineral content, but the animals' physical symptoms and performance suggest deficiencies.
3. Get Professional Help
If possible, work with a nutritionist to formulate specific recommendations. He or she will be able to spot the possible presence of mineral antagonists.
“Sometimes minerals can act against each other,” says Wright. “For instance, the more sulfur and molybdenum there is in the diet, the more that copper availability is reduced. In order to overcome the antagonism, copper would need to be supplemented at levels beyond what animals normally require.