Trace mineral management can have a significant impact on beef cattle production, influencing herd reproduction, immunity, calf development and overall efficiency, according to Dr. Jerry Rusch, beef cattle veterinarian and technical service veterinarian with Axiota Health. Rusch spoke about the importance of trace minerals during a recent webinar hosted by ANCW.
Rusch explained that while trace minerals are required by cattle in much smaller amounts than macrominerals, those small quantities are still critical to cattle health and performance. “They’re needed in very small amounts, but that very small amount is critical for optimal reproduction and optimal immune function,” Rusch said.
Macrominerals include nutrients such as calcium and phosphorus, while trace minerals include copper, zinc, selenium and manganese. Rusch compared the difference to adding ingredients to a mineral feeder. “With your macro minerals, it’s like taking that big mineral feeder in the middle of the pasture, and I’m going to add a bucket of calcium to it, and I’m going to add a bucket of phosphorus and a bucket of sodium and that kind of thing,” he explained. “But when I get to the trace minerals, I’m going to add a tablespoon and a teaspoon, very small amounts.”
Despite those small quantities, Rusch said a deficiency can have consequences that are much larger than the amount of mineral involved. “But if we have even a small deficiency of that, it can have far-reaching impact on, like what I was talking about, the reproduction and immunity,” he said.
Trace Minerals Can Affect Herd Efficiency
Rusch said the ultimate goal of managing trace minerals is improving the efficiency of the beef herd. Small improvements in reproductive performance, calf survival or weaning numbers can translate directly into economic returns for producers. “Because you know what we’re looking at overall is improving the efficiency of your herds,” Rusch said. “Because when we improve your efficiency, whether that be we get one more calf born per year, or we wean a few more calves, or we lose less calves due to sickness, that translates into dollars in your pocket.”
He also emphasized that producers may not recognize a trace mineral deficiency until cattle have already experienced significant impacts.
As trace mineral levels decline, Rusch said the immune system can be affected first, followed by fertility and eventually growth. “But clinical signs where you can actually look at a cow and tell it has a trace mineral problem is pretty hard to see,” he said. “By the time you see that, is the tip of the iceberg. You have so many problems. You’ve given up so many things with the immune system, fertility, and growth.”
That makes managing mineral status before obvious clinical symptoms appear particularly important.
Drought Can Create Additional Mineral Challenges
Rusch also discussed the relationship between drought, forage quality and trace mineral availability. Dry conditions can change the plant itself while also affecting how minerals move from the soil into forage. “When you have a drought, a plant will actually get more fiber, more lignin in it, and that actually results in the animal not being able to digest it as well, so it can’t get to the trace minerals,” Rusch said.
Water availability can also affect mineral uptake by plants. “For the plant to take up the trace mineral from the soil, it needs water, and if there’s not enough water, we can have issues with that with drought,” he said. “So it actually causes poor quality forage.”
For cattle producers dealing with drought, Rusch said that means mineral management needs to account for what cattle are actually receiving from their forage and environment rather than simply assuming supplementation is solving the problem.
Mineral Absorption Matters
Putting mineral in front of cattle does not necessarily mean the animal is absorbing all of it. Rusch discussed mineral antagonism, in which other minerals or compounds can bind trace minerals and prevent cattle from utilizing them. “There can actually tie up the mineral absorption to where it’s going into them, but the body isn’t getting it,” he said.
Rusch said this can occur for several reasons, including poor mineral intake, mineral antagonism, water quality and soil quality.
He used newly weaned calves as one example. “If it’s mixed into the feed, maybe they’re not eating a lot of feed,” Rusch said. “So think about weaned calves. You first wean them, and their intake is not very good.”
Water quality can also play a role, particularly when water contains high levels of sulfur. “We kind of have to look at getting it into the animal, and then antagonism in the rumen where things are grabbing a hold of it,” Rusch explained.
Trace Minerals and Reproductive Performance
One of the most important areas Rusch addressed was reproduction. He said trace mineral supplementation can support reproductive performance in several ways, including calving distribution, pregnancy rates and semen quality.
With injectable trace minerals, Rusch said studies have shown improvements in calving distribution. “The studies have shown actually compressing your calving distribution,” he said. “That’s talking about every 21 days, how many calves are born after your breeding season.”
Rusch said producers want as many calves as possible to arrive during the first 21 days of the calving season. “A lot of times we talk about an ideal 60, 63-day breeding or calving season,” he said. “I’m going to tell you, very few of my clients did that. They always lengthened it out, but we want to have as many calves born in the first 21 days.”
He said trace minerals can also contribute to pregnancy rates and semen quality.
Rusch outlined three ways adequate trace mineral status can support reproductive performance. First, minerals can help the cow recover following calving. “It’s helping that cow that had a calf clean up her uterus because there’s bacteria that gets inside of there,” he said.
Second, trace minerals play a role in hormone production. “Zinc is very important for the formation of” prostaglandin, Rusch explained, while “copper and manganese” are important for estrogen production. He added that manganese is important in forming progesterone, which is critical for maintaining pregnancy.
The third area is early embryo survival. “When we look and we first breed a cow, almost every cow time zero is pregnant,” Rusch said. “But like within the first 10 days, 20% of the cows resorb their fetus.”
He said additional losses can occur over the following days, making early embryonic survival an important part of reproductive performance. “These trace minerals help prevent that early embryonic death,” Rusch said.
Calf Trace Mineral Status Begins Before Birth
Rusch also highlighted the importance of the last trimester of pregnancy in establishing a calf’s trace mineral status.
During late gestation, he said the cow transfers trace minerals from her liver into her bloodstream, allowing those minerals to reach the developing calf. “As she goes into the last trimester, you see that her liver levels drop because she is pulling trace minerals out of her liver, saturating her blood,” Rusch said. “And then that circulates into the calf.”
That transfer is important because milk and colostrum are relatively poor sources of trace minerals. “Milk and colostrum are very poor sources of trace mineral,” Rusch said. “So that calf, this is how God built the cow, that she transfers it to the calf in the last trimester. So when it hits the ground, it has trace minerals in it.”
Early-Born Calves Can Have an Advantage
Rusch said improving calving distribution can have value beyond simply getting more calves born earlier. Calves born early in the calving season tend to be heavier at weaning and can also provide better candidates for replacement selection.
He referenced research showing a greater percentage of calves born during the first 21 days among cattle receiving the mineral treatment. “Calves born early are your heavier calves,” Rusch said. “When you go to wean, they’re worth more money.”
He also said those early-born calves can be valuable when selecting replacement heifers and bulls. “I always tell my clients if you’re going to keep heifers, they definitely need to come out of that first group that’s born, don’t keep them out of the third,” Rusch said.
According to Rusch, females born early in the calving season are more likely to cycle and become pregnant, less likely to experience dystocia and more likely to breed back during the following breeding season.
Overall, Rusch said trace mineral management should be viewed as an important part of a larger herd-efficiency strategy. From drought-stressed forage and water quality to mineral absorption, reproduction, calf development and immunity, he emphasized that small amounts of trace minerals can have significant consequences for cattle performance.
