Trace minerals (TM) play fundamental roles in the function and maintenance of the immune system. Because the supply of some TM in mare milk may be insufficient to
meet foal requirements, TM deposited in fetal tissues during gestation serves as an important reservoir for the nursing foal. Greater bioavailability and retention of TM amino acid complexes (CTM) compared to inorganic TM has been observed in several species. The aim of this study was to determine if dietary TM source and duration of supplementation in the mare alters TM status and immune function of the foal.