Many nutritional components are essential for the rations of a successful dairy herd – including a few that barely show up in a test.
Dr. Tony Rickard, the just-retired University of Missouri Extension dairy specialist for the southwest region, described it as being like an orchestra. “Right before they do a concert, they each tune their instruments; they’re fine tuning,” he told Ozarks Farm & Neighbor. For dairy rations, “the place we have to start is with the major ingredient in the ration, which is forage, and making sure that it is extremely high quality…and then we fine tune a bit with our macrominerals, and with our microminerals.”
Macrominerals are those which are needed in larger quantities, like calcium; the micro, or “trace” minerals, include selenium, zinc and copper, and are measured in much smaller doses. “Most of the time we’re actually going to be exceeding the requirements,” said Rickard. “We’re talking about requirements of 20 or 40 parts per million; we’re going to be fairly close in most rations.”
But they’re just as crucial as the nutrients that are needed in larger amounts. Selenium, for instance, is what is known as a “coenzyme,” a chemical needed for one of the body’s enzymes to perform its metabolic tasks. “It’s an anti-oxidant,” Rickard explained. “We know that it’s important in the immune system, giving that cow all of the necessary tools for her to combat any type of a challenge, whether it be a bacteria or a virus, that would compromise the health of the animal.”
He said rations can vary in their trace mineral contents; zinc is sometimes low and needs to be supplemented, while copper varies. “The cow is a very resilient animal, and until you get into major deficiencies it’s going to be difficult to pinpoint a trace mineral deficiency,” he said. “Unfortunately, a lot of producers don’t get the total mineral profile when they do a forage analysis. They really do need to do that, because it’s a shot in the dark.”
That’s one reason Dr. Dan Tracy, technical services veterinarian for Multimin, recommends injectable trace minerals, which he said provide a supplementary benefit during a key period in the cow’s cycle. “During the dry period immediately before she calves and after she calves, we’re asking this cow to calve, to heal and to produce milk, which is a pretty large metabolic demand on the system,” Tracy told OFN. “Injectable trace minerals help ensure that she gets what she needs, because during that time she’s not going to be consuming feed as much as she does after she heals and after she gets into lactation.”
Tracy, who spoke at the recent Missouri Dairy Expo in Springfield, Mo., and at other events in this region, said copper and selenium work in the animal in tandem. “What you see is these trace minerals involved with metabolism, energy, protein production, hormone production and the immune system,” he said. “And when we start talking about antioxidants, we’re talking about protecting these animals against oxygen stress, which can be harmful… Trace minerals are included in the ration in a very small amount, but the effects they have on animals is pretty profound.” You can get too much of a good thing, too; there are areas of the U.S. where the soil has excess selenium, and the forage can be toxic to cattle. But that’s not the case in the Midwest or the Mid-south; Tracy said in Missouri, Arkansas and Louisiana, selenium deficiency is more of an issue.
He noted the importance of maintaining a good balance in having a successful lactation. “When you see a breakdown in a cow’s lactation and she loses milk production, she loses an excessive amount of weight or suffers from a metabolic disease, you link it back to poor feed intake or a disease process that prevents her from consuming the feed that she needs,” Tracy said. One of those things could be sulfur; where there’s too much of it in the feed or water, it ties up the nutrients and prevents the cow’s body from gaining access to them.
