November 2018
Feeding Facts

The Root of All Things Feed Part 5: Minerals

We have talked about protein, carbohydrates, fats and vitamins. The first three are simple when it comes to how they work. Vitamins are a bit more complicated. Minerals, which we will discuss now, are by far the most complex of the nutrients in many ways. Too little or too much of any one of them can affect how the others react and perform within an animal. That clouds the picture in many cases. The form that they are in when ingested also has a great deal of influence on how they are absorbed and used by the animal. It gets complicated quickly, but since they are very important to livestock on all levels and in all situations, then we need to delve into the murky waters.

Minerals generally are divided into two categories, Macro and Micro, based on the amount that is needed for day-to-day activities. Macro minerals include calcium, phosphorus, sodium, chlorine, magnesium, potassium and sulfur. Micro minerals include cobalt, copper, fluorine, iodine, iron, manganese, selenium and zinc. These minerals combine to make up from 3 to 5 percent of an animal’s body weight in dry matter and in most animals, calcium is approximately half of the total mineral and phosphorus comprises one-fourth.

With 15 or so minerals involved, there is not space to go into the function and signs of deficiency or toxicity for each one. Frankly, that would make for boring reading unless you have animals with issues. I will, however, hit the high spots and list some general functions. Calcium, phosphorus, magnesium, copper and manganese are important for skeletal formation and maintenance. Phosphorus, sulfur and zinc are important in protein synthesis. Iron and copper are needed for oxygen transport in the blood. Sodium, potassium and chlorine all play a role in fluid balance and regulating the pH of the entire system, and the list goes on and on.

Deficiencies are easily seen with several of the minerals and include things like rickets, blindness, anemia, loss of hair, perosis, white muscle disease, goiter and many more. While deficiencies can cause so many issues, toxicity is also as bad or maybe worse, and more common than deficiencies. Some toxicity symptoms mirror deficiency symptoms and complicates things greatly. Toxicity with many minerals inhibits the use of some other minerals and vitamins and really makes for a complex problem to solve.

Forage plants are usually a good source of several of the minerals, and grains tend to have a little. That is all dependent on the mineral levels in the soil on which they were grown. Since many soils are deficient in one or more minerals and some animals spend little to no time grazing, we tend to supply minerals either as a free choice mineral or incorporated into the feed that is being given. Generally, grazing livestock will be offered a loose mineral and confined livestock (pigs and chickens predominantly) will have a feed that has minerals balanced to meet their needs without getting into toxicity or deficiency situations.

Heavy applications of manure to soils and heavy feeding of grain byproducts are two of the most common ways to get an imbalance in mineral nutrition. Manures tend to be heavy in phosphorus, which will build up in the soil and, at some point, cause issues with calcium metabolism. Byproduct feeds are made by removing some portion of a grain while leaving all the other nutrients intact. Corn gluten is made by removing the starchy portion of the corn kernel, while leaving the protein, vitamins and minerals behind. Those ingredients are now more concentrated and can lead to toxicities if that is not accounted for. The same factors can cause problems in any of the byproducts.

When considering minerals, you must also look at the actual source of the mineral. They come in many forms. Chelated is a word that you often hear and for good reason. Chelate means that the object (mineral in this case) is bound to (connected to) something else. In mineral nutrition that is almost always an amino acid. If you remember from our article on protein, amino acids are the basic building blocks of proteins and by binding a mineral to an amino acid, we basically trick our intestine into absorbing the mineral more efficiently. So, with that said, generally chelated minerals are absorbed more efficiently than other forms.

There are several other forms that minerals come in. There are oxides, dioxides, carbonates, sulfates, chlorides, gluconates, citrates, fumarates and probably a few more. The most common two that you will see on a feed tag are oxides and sulfates. Generally, but not with every mineral, the sulfates will be a bit more absorbable and have the added benefit of providing a little sulfur. That is not true in every case but is a general thing to keep in mind. Feed tags themselves only must guarantee protein, fat and fiber for feeds, but mineral supplements do have to list some of the macro minerals in most cases. The place to really find out more about the mineral quality from the feed tag is in the list of ingredients where it will be spelled out if it is a chelate, sulfate or oxide.

As you look to buy minerals, keep in mind the source and the fact that source influences how much is available to the animal. Tags that show high levels may not be as good as a tag with a lower percentage if it is more available to the animal. There is new research out there with some chelated minerals that may, in time, change what we think we know about what the animals need.

So, feed good minerals from a reputable source and ask lots of questions. Minerals are generally not cheap but more than pay for themselves in growth, reproduction and overall animal health. Feeding a good standard mineral mix is the best option, unless you rely heavily on byproduct feeds or have other mitigating circumstances.

 

Jimmy Parker is AFC’s animal nutritionist.