By Heather Smith Thomas
We are what we eat, as the old saying goes. The same is true for cattle.
For healthy animals, diet must contain adequate amounts of protein, energy, vitamins, and certain minerals, such as sodium, calcium, and phosphorus.
Sodium chloride — salt — should always be provided because cattle need more salt than what occurs naturally in forages. Bone growth and milk production depend on calcium and phosphorus.
These minerals are called macro-minerals because they are required in fairly large amounts. And because these minerals are usually present in high levels in many feeds, deficiency is generally not a problem.
Cattle need other minerals to stay healthy, but these are needed in only trace amounts, and so are called micro-minerals. These micro-minerals may be required only in small amounts, but they carry large responsibility; reproduction, skeletal development in young animals, optimum health, and strong immunity all depend on these important trace minerals.
Some soils and plants are short on certain trace minerals, leaving feeds deficient. In these situations, cattle may suffer various ailments. So, even if your cattle are grazing on lush fields or getting quality forage, it’s important to provide them with these micro-minerals:
Selenium, along with vitamin E, is very important for producing an enzyme that protects muscle cells from damage, and is essential for muscle function. Selenium deficiency causes white muscle disease in young animals, retained placenta and infertility in cows, abortions, and premature or weak newborn calves.
Selenium deficiency can lead to increased susceptibility to disease and impaired heart function in young animals. White muscle disease can occur unless the dam was supplemented or the calf is given an injection of selenium at birth. Calves with white muscle disease may die suddenly because the heart muscle is impaired.
Selenium has a narrow margin of safety, however, because too much can be toxic, causing loss of tail hair and unhealthy feet or even loss of hooves.
Cattle are unhealthy if they don’t have enough, and unhealthy if they have too much. In most geographic areas of the United States, soils are deficient in selenium, so supplementation is necessary.
Copper plays a role in blood health, bones, pigment production, hoof, horn, and hair formation, and growth. It also is crucial to a healthy, strong immune system.
Low copper levels can result in reduced weight gains, impaired immune system, broken bones, or lower reproduction rates. One of the most visible signs of copper deficiency is change in hair color. Black animals develop a red tint and red animals become bleached and light colored. The coat becomes dull and is slow to shed in the spring.
In young animals, copper deficiency can result in diarrhea, higher incidence of diseases, lameness, and poor response to vaccination. Bones may be weak and brittle. Heifers may be late reaching puberty and fertility may be impaired. Cows may be slow to cycle after calving.
Zinc is important in carbohydrate metabolism, hoof structure and soundness, and male fertility.
Zinc-deficient calves may have swollen feet, scaly skin with open lesions, wounds that take longer to heal, loss of hair, excessive salivation, reduced appetite, reduced feed efficiency and growth rates, and impaired immune systems.
Moderate deficiencies are subtle, such as decreased growth rate and impaired immunity and fertility. Calves born to zinc-deficient dams have lower levels of immunity even when fed adequate amounts of zinc.
Manganese is highly important for proper bone and cartilage formation — which directly affects bone growth in young animals. It is also crucial for optimum fertility in cows.
Deficiencies may result in impaired reproduction. Signs of deficiency in calves include low birth weight, skeletal deformities and contracted tendons in newborns, swollen joints, and stiffness.
Iodine influences metabolism and the birth process. Iodine-deficient cows may have weak, hairless, or stillborn calves. Many areas of the United States are iodine-deficient so this trace mineral is often added to protein supplements and salt.
Your cattle can get the right amount of micro-minerals by feeding them protein supplements or salt/mineral mixes provided free choice as blocks or granulated products.
Because free-choice consumption is varied, with some animals eating too much — which can be toxic — while others eat too little or none, some cattle owners make sure their cattle receive the necessary minerals through dosing by drench, bolus, or injection.
Getting the necessary minerals is particularly important during the cow’s pregnancy, because copper, manganese, and zinc are stored in the liver of the developing calf fetus.
A deficiency cannot be “caught up” by supplementing the cow after she calves, since they are not passed through milk, except colostrum, and until the calf starts consuming a mineral supplement on his own, he will be deficient.
Make sure your cattle get the right macro- and micro-minerals, and you’ll enjoy a healthy herd.