Today, most dairymen and stockmen realize that cattle have established requirements for several mineral elements. Animals require these minerals because each element participates in one or more of the chemical functions that keep the body operating and producing normally.Our objectives in mineral supplementation is then to make sure we provide all of the necessary mineral elements for the biological functions of the cow. No matter what kind of feed ingredient or supplement we provide, we want to know it will benefit biologically and that we will realize some economic benefit for our efforts. When it comes to deciding which mineral supplements to use in livestock feeding, two criteria need to be considered: Biological efficacy and economic efficiency.
The dictionary defines efficacy as "power or capacity to produce the desired effect; ability to achieve results; effectiveness." Efficacy is a good thing, and in the context of mineral supplementation, we want supplements to be usable by the animal, or efficacious. We want supplements to prevent deficiencies and promote good health, reproductive performance and milk production. Efficacy, however, does not take into account the cost of producing these desired effects.
The dictionary defines efficiency as "acting or producing effectively with a minimum of waste, expense or unnecessary effort, and exhibiting a high ratio of output to input." Economic efficiency is an important consideration when it comes to feeding cattle. With regard to mineral supplementation, we want mineral supplements to produce the desired effects for the least possible cost. In other words, we want the most "bang for our buck."
There are a number of possible sources for each of the essential elements that cattle require. In this context, source refers to the actual chemical compounds (the chlorides, oxides, carbonates, etc.) that supply the element. This is not to be confused with companies or tradenames for various products. Sources of the mineral elements differ with regard to their efficacy. In other words, some sources of mineral are not used as well by the animal, or they are less bioavailable; whereas other sources are used well, or are more bioavailable. Additionally, some sources of mineral supply more of the element than others (which affects their inclusion rate in the supplement), and some sources of mineral cost more than others. All of these factors must be considered when evaluating the economic efficiency of different mineral sources.
Three critical trace elements required by cows, copper, zinc and manganese, will be used to illustrate the specifics of efficacy and economic efficiency of using different mineral sources. To put this discussion into proper perspective, remember that all three of these elements combined represent less than 1 percent of a lactating dairy cow's daily mineral requirements. This doesn't mean they're not important, but it does mean they shouldn't have a tremendous influence on the cost of a bag of supplemental minerals (even though they sometimes do!).
Two broad categories of sources are available to supply these elements. One category is the inorganic sources. Inorganic mineral sources are the common oxides, chlorides, sulfates and carbonates of the element (like zinc oxide, zinc sulfate, etc.), and these can differ in their efficacy or bioavailability. The other category is the organic sources, often referred to and marketed as "chelates," "complexes" or "proteinates." Organic mineral supplements are produced by manufacturing processes that take the metal elements from an inorganic source and attach the metal to an organic molecule, most commonly an amino acid or another part of a protein molecule. This form of mineral tends to be just as bioavailable or efficacious as the most bioavailable inorganic sources of mineral.
Unfortunately, it usually costs considerably more to supplement the same amount of mineral from an organic source as it does an inorganic source. This means that organic minerals tend to be much more expensive per unit of element supplied. Also, many controlled scientific studies have shown little difference in efficacy of organic minerals compared to the more-bioavailable of the inorganic mineral sources.
So, what does all of this mean with regard to practical efficacy and economic efficiency of mineral supplementation? It means you must supplement with a mineral source that is bioavailable, if you want your livestock to perform well. Make sure your mineral dealer sells you a product that contains those sources designated as highly bioavailable. It also means that if you want a high ratio of output to input, you need to make sure you are not paying more than is necessary per unit of element. Copper, zinc and manganese products are commonly sold in organic form but provide for only a small percentage of the cow's daily mineral needs. The organic products may be very efficacious in meeting the cow's biological requirements; however, they often cost more per unit of usable element than those inorganic sources we know to be efficacious.
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