Organic trace minerals in ruminant nutrition

This paper defines the various types (complexes, amino acid chelates and proteinates) of organic trace minerals commercially available and reviews research regarding their bioavailability and effects on physiological responses in ruminants. The addition of one or more organic trace minerals to cattle diets has increased growth, milk production, reproduction and/or immune response in some studies. It is not possible to determine from some of the studies if the responses observed were due to the organic mineral(s) per se or simply to increased dietary mineral intake. Zinc methionine has been studied to the greatest extent of any of the chelated or metal complex products available. The mode of action of trace mineral chelates or complexes is largely unknown. Based on apparent absorption or tissue and blood concentrations, little evidence is available to suggest that organic trace minerals are considerably better absorbed than inorganic forms. In explaining the beneficial responses to certain organic trace minerals, the quantity of mineral absorbed may not be as important as the form of the mineral absorbed. Further studies with organic trace minerals are needed to better define conditions where performance or health responses may be expected and to determine the mode of action whereby organic trace mineral supplements improve ruminant performance.