Trace minerals such as Zinc, Copper, Selenium and Manganese are important for optimal immune function and reproduction in cattle. Stressed animals have decreased appetite, resulting in less feed intake which means reduced trace mineral intake. Typical stressful times for cattle are around calving in cows and breeding in cows/heifers/bulls or during handling of calves and yearlings at branding, weaning, transporting and feedlot receiving time. Inadequate trace mineral supplementation and large variations in oral mineral intake may also negatively impact the trace mineral status. Antagonists such as sulfur, molybdenum, iron and calcium in feed and water may impair absorption and/or bio-availability of orally consumed trace minerals. The trace mineral requirements of cattle are not static and change during their production cycle and also during these times of stress. When the trace mineral status of cattle declines, immunity, enzyme functions, growth and fertility are compromised.