Bioavailability

When designing a mineral program the most important aspect impacting its benefit to the animal is bioavailability. This is true regardless of species. For this reason the goal of QualiTech’s current research program is to examine the bioavailability of our SQM products compared with their most available inorganic counterparts. Figure 1 shows the bioavailability of a number or organic zinc sources compared with both zinc sulfate and zinc oxide. On average, all of the organic zinc sources are more than twice as bioavailable than the most available inorganic source, zinc sulfate, and three times more available than zinc oxide.

So what is bioavailability and why is it so important? In its simplest definition, bioavailability is the amount of an ingested mineral that the animal is able to digest, absorb, and use for some metabolic function. The reason this is so important is because if a mineral is not bioavailable, the animal may not be able to consume enough of the mineral to meet its physiological needs. In the end, this could result in decreased productivity which in turn can decrease profits.

Dietary Antagonism

There are a number of factors, both animal and dietary, that can influence mineral bioavailability; however, one of the most insidious is dietary antagonism. Dietary antagonism occurs when one component of the diet decreases the availability of another component. This is of particular concern in diets where inorganic trace minerals, like zinc or copper sulfate, are fed. When inorganic trace minerals are consumed, they break down within the digestive tract and are free to interact with other portions of the diet. This can lead to the formation of insoluble compounds that the animal can neither digest nor absorb. Organic trace minerals, on the other hand, are firmly bound to an organic compound and do not break down until they reach the small intestine where they can be readily absorbed. Being bound to the organic compound provides protection to the trace mineral, thereby preventing dietary antagonism. Figure 2 shows the greater bioavailability of SQM zinc compared with zinc sulfate when an antagonist (cottonseed hulls) is fed in poultry diets. Without the antagonist, SQM zinc was 10% more available than zinc sulfate while in the presence of the antagonist, SQM zinc was 40% more available.

Reproduction

In most bioavailability trials, researchers are looking for a response in absorption, retention, or tissue concentration of the target trace mineral. However, trials that evaluate growth, reproduction or immunity can also be used to illustrate evidence of increased bioavailability. Figures 3 and 4 show the effect of feeding SQM trace minerals as the sole zinc, copper, and manganese source compared with 100% mineral sulfates and 2/3 sulfates:1/3 organic trace mineral blends on services per conception and first service conception rate, respectively. The greater bioavailability of the 100% SQM trace mineral treatment resulted in fewer services per conception and a higher overall first service conception rate.

Immunity

This same increase in bioavailability can also be seen in trials evaluating immune function. Figure 5 shows the IgG titer response to a foreign antigen in cattle supplemented with either SQM Zn or zinc sulfate. Cattle that received SQM zinc had a greater titer response than cattle fed zinc sulfate indicating that they were better able to mount a defense against the foreign antigen.
Figure 6 comes from the same trial as figures 3 and 4. This trial showed that cattle fed both the 100% SQM trace mineral treatment and the 2/3 sulfate:1/3 SQM trace mineral blend treatment had a much lower incidence of mastitis.

Taken together, this research shows that by feeding a good, bioavailable trace mineral, like SQM, can have a positive influence on animal production, especially in situations where dietary antagonists are present.