Winter Cattle Journal 2019: Managing Minerals
Minerals play an important part in livestock health and immunity, but when it comes to establishing a mineral program there is no “one size fits all” solution.
Beef cattle require seventeen minerals to maintain good health. These minerals are divided into two groups: macrominerals and microminerals. Macrominerals include elements such as calcium, magnesium, phosphorus, potassium, sodium, chlorine, and sulfur. The remaining minerals are called microminerals or trace minerals because animals require them in much smaller quantities. Trace minerals, which are stored in the animal’s liver, include chromium, cobalt, copper, iodine, iron, manganese, selenium, and zinc.
Determining which minerals need to be supplemented always depends on the region and its forage and water sources that are available. In general, the Midwest is sufficient in phosphorus, iron, and sulfur. However, trace minerals zinc and copper are typically deficient across the Unites States.
Producers who want to create a mineral program that will serve their herd most effectively should begin by taking samples of their forage, other feed sources, and water and connecting with their local extension office for guidance.
Adele Harty, South Dakota State University extension cow/calf field specialist, recently developed and began working with ranchers through a cattle mineral nutrition program. Her yearlong program begins with face-to-face sessions with producers to educate them about basic nutrition and the roles that minerals play in animals’ health. After that, she works with ranchers to collect forage and feed samples in the spring, summer, and fall to “get a profile of what minerals are available to the animals.” In the fall, she hosts a session to discuss how the samples are interpreted in the lab, and she works with the producers to find a commercial mineral that meets their needs or makes plans for a personalized mineral to use.
Mary Drewnoski, assistant professor and beef system specialist at University of Nebraska-Lincoln recommends that for the best data, producers should take samples of what their cattle are eating once a season. Taking samples during different seasons tracks which minerals are present in the early, mid, and mature stages of the forage. Ideally, producers should also take samples over three years to get a clear picture of the changes in mineral content in relation to rainfall.
As a rule of thumb, 50 percent of the mineral content found in forage is actually available for absorption into the animal. For example, if the forage contains 10 parts per million (ppm) of a trace mineral, you could assume that 5 ppm of that mineral will actually be absorbed by the animal.
“Not all that is consumed is being absorbed,” Drewnoski said.
Mineral content within forage can change from region to region, which is why it is important to know the needs for your specific location and resources.
Harty described that selenium toxicities are a common issue in western South Dakota, but on the eastern side of the state, producers often are deficient in selenium. Selenium toxicities are a huge issue for horses, which will start losing their mane and tail and begin sluffing off their hooves. Cattle are more resilient to toxic levels of the element, but are still affected.
The problem with mineral deficiencies isn’t always that there is a lack of minerals in forage, but often different elements negatively react together, forming compounds that cattle are unable to absorb and therefore use.
For example, iron, molybdenum, and sulfur act as antagonists against copper absorption. Drewnoski explained that these antagonists “bind to copper and create an insoluble complex that never enters [or is absorbed by] the animal.”
Water in the Midwest tends to be high in sulfur and distiller grains are typically high in molybdenum which both negate copper supplementation.
Producers can also adversely affect their herd by supplementing iron when the forage supplies an adequate ration to begin with, especially since iron can have negative absorption effects on copper.
“Redder is not better,” Drewnoski advises producers when purchasing a mineral supplement.
“One of the challenges we talk a lot about in mineral consumption is free choice,” Harty said. Free choice is the most common method used to distribute minerals, but it is not an exact science.
Harty explained that ranchers might assume that because their cattle are not eating the provided minerals that they don’t need them, but she went on to say, “That is probably not the case, it’s probably a palatability issue or an imbalance with it.”
Stephanie Hansen, associate professor and beef feedlot nutrition chair at Iowa State University, also cautions against assuming that cattle will consume the mineral that they need.
“Remember cattle have no nutritional wisdom, just like humans reach for the salty potato chips instead of nutrient rich broccoli, cattle are driven to consume mineral based on palatability (largely driven by salt content), not by some knowledge that they are deficient in a certain mineral,” she said.
Typically, free choice minerals are salt driven; however, some minerals that have a bitter taste—like those containing high levels of magnesium—may need a sweetener added to mask the taste.
Adding salt to mineral solves a macromineral deficiency and boosts consumption.
“In forage-based diets, cattle are pretty much always deficient in salt,” Drewnoski said.
Another way for producers to supplement is through injectable minerals. Drewnoski said injectable minerals can be a good way to improve mineral status quickly during a period of high need or in a case where the animal has no trace mineral stores built up.
This form of supplementation should always be used in combination with a free choice mineral. In addition, ranchers must use caution when using injectable minerals because they are typically high in selenium which could lead to toxic levels.
Recognizing trace mineral deficiencies is difficult because the symptoms that cattle may show could be caused by issues not related to mineral status.
“Unfortunately, trace mineral deficiencies are often difficult to spot, as until they are severe there often are not obvious signs. The most practical way is for ranchers to assess their feed and water sources for trace minerals and for antagonists to trace minerals,” Hanson said.
“It is really hard to use production performance data or health records to say that I’ve got a mineral problem,” Drewnoski said. “Most people don’t see frank deficiencies except for milk fever and grass tetany.”
Along with testing forage, producers can also have their animals tested by their vet through a liver biopsy if they have that need.
At different periods throughout the year (gestation, lactation, reproduction, weaning, etc.), the animals’ mineral needs may fluctuate; however, establishing and maintaining a consistent mineral program should be sufficient to supply the animals’ needs.
“If you have a good mineral program year-round, you don’t need to change anything,” said Drewnoski.
Establishing a mineral plan specific to a producer’s herd is key to maintaining general health.
“Everybody’s situation is going to be different and it takes time to evaluate what their needs are and what is going to boost that,” Harty said.
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