The bioavailability of minerals, or the proportion of the mineral that is absorbed from the diet into circulation, varies based on a number of factors, one of which is their chemical form. | Photo: The Horse Staff

Q. When looking at the ingredients in various feeds, I notice there seem to be different types of the same mineral. For example, I’ve seen zinc oxide, zinc proteinate, zinc methionine, and zinc amino acid complex. What is the difference between these, and is one better than the others?

A. First of all, well done for looking at feed labels in such detail and noticing this difference! You are correct that the same mineral exists in different forms. This not only applies to zinc but also other trace minerals, such as copper and manganese. Less frequently you will find different versions of macro minerals such as calcium and magnesium.

The bioavailability of minerals, or the proportion of the mineral that is absorbed from the diet into circulation, varies based on a number of factors, one of which is their chemical form. Minerals bonded to an inorganic compound (one that does not contain carbon) are known as inorganic minerals. Examples of inorganic minerals include oxides and sulfates, and they tend to be easy and inexpensive to produce. Generally, inorganic sources of macrominerals (calcium, phosphorus, magnesium, sodium, chloride, and potassium) have relatively high bioavailability; however, inorganic trace minerals are less bioavailable