February 2009
Feeding Facts

Feeding Facts

Livestock producers have long recognized the nutrient profile for forages and ingredients are different. While most producers consider the protein and energy level of a feedstuff, few ever consider the mineral levels in these feeds as part of the overall nutrition program. Over the past several months those who have purchased minerals have noticed a sharp increase in the cost. With the increase in price, several producers are becoming more aware of the fact their forages will provide livestock different levels of minerals. The minerals provided by these forages will allow you to select a mineral that might allow you to save money while coming closer to meeting the overall mineral needs of your animals. Let’s review some of the factors affecting mineral concentrations in feedstuff so you might make a better decision when selecting an adequate mineral for your herd.

Mineral concentrations in forages are affected by five different factors: 1) the genus, species or variety of forage, 2) type and mineral concentration of the soil, 3) stage of plant maturity, 4) climatic or seasonal conditions and 5) region of the country.

Legumes like clovers, alfalfa and peanuts are higher in calcium, potassium, magnesium, copper, zinc, iron and cobalt while grasses like fescue, bahia and bermuda tend to be higher in manganese and molybdenum. Therefore, if you are utilizing a legume as part of your forage program, you would consider a mineral higher in phosphorus, manganese and molybdenum while being lower in calcium, potassium, copper, zinc and iron. If your forage is predominantly grass, you would look at a mineral higher in calcium, potassium, magnesium and copper.

Another factor to consider is the type and mineral concentration of the soil. This is extremely important since forages will mimic the soils they are grown in. Grasses grown in under-fertilized soils will have inadequate levels of minerals. It is important to remember that just because a mineral is in the soil, does not guarantee the forage will uptake that mineral in adequate levels or in a form that can be utilized by the animal. Several companies recommend taking a forage sample and using these results to develop a mineral program. This can also cause problems because the minerals being in the forage does not mean the animal can utilize them.

Soil pH will have an affect on minerals. As soil pH increases, molybdenum uptake increases while zinc, copper, cobalt and manganese decreases. Also if you are growing grass on soils fertilized with chicken litter, you will elevate levels of calcium, phosphorus and potassium.

Stage of maturity will also have an affect on the mineral levels of forages. Generally, there is a rapid uptake of mineral during early growth and gradual dilution as the plant matures. Copper, zinc, iron, cobalt and molybdenum are the most common elements affected by plant maturity. Therefore, if you go by this, you should provide a product with higher levels of minerals in the late summer and fall over early spring and summer.

Climatic and seasonal changes play a role in mineral composition of forages. Leaching of soluble nutrients during wet weather is well-documented. Copper, zinc and manganese tend to be bound in plant tissues and are less susceptible to leaching than minerals like potassium and phosphorus. It is important to remember cool-season grasses have higher levels of potassium nitrate and lower levels of magnesium needed for the prevention of grass tetany.

A final consideration is the region of the country in which you reside. This is very important if you use a mineral coming from a plant outside the Southeastern United States. Minerals developed in these areas will not provide the levels of minerals required by cattle in the Southeast. Copper deficiencies tend to be along the East and West Coast, Upper Midwest and Florida. Zinc deficient areas include the Southeast, Texas and the West Coast. Signs of zinc deficiency include poor performance, foot rot and slowed wound-healing. Iodine deficient areas include most of the northern-half of the U.S. and parts of the Southeast. Plants along both coasts are known to be deficient in manganese. High levels of calcium and phosphorus also increases the requirement for manganese. Severe selenium deficiencies have occurred in the Southeast with deficiencies including white muscle disease, poor fertility and reduced immune response.

In summary, a lot of factors go into selecting the best mineral for your individual operation. One thing is certain, cattle need minerals provided on a daily basis to perform at their highest level. There is no way for each individual producer to have a mineral designed for their individual operation. Therefore, it is important to select a mineral best suited for your forage and feeding program along with the factors discussed in this article. While this method may not provide the exact levels of minerals, it will be your very best option when selecting a mineral.

If I can help you in this process or if I can answer any questions you might have concerning this or other nutritionally related questions, please call me at (256) 947-7886 or e-mail at
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Jimmy Hughes is AFC’s animal nutritionist.