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A number of trace minerals are required by beef cattle. Feeds consumed by cattle may supply most trace minerals in adequate amounts. However, some minerals may be severely or at least marginally deficient in beef cattle diets. Even marginal mineral deficiencies can reduce growth, reproduction and/or health of cattle showing few if any clinical signs of deficiency. Other trace minerals such as iron and molybdenum may be naturally present in feeds in levels high enough to reduce animal productivity.
Certain trace minerals affect immunity and may affect disease susceptibility in cattle. Selenium, copper, zinc, cobalt and iron have been shown to alter various components of the immune system. Reduced disease resistance has been observed in ruminants deficient in selenium, copper and cobalt. Trace mineral deficiencies may also reduce the effectiveness of vaccination programs by reducing the ability of the animal's immune system to respond following vaccination.
Calves that have been stressed due to recent weaning and shipping exhibit lowered immunity and increased disease susceptibility; therefore, an adequate supply of trace minerals is especially critical in beef cattle receiving diets for stocker cattle. Feed intake is decreased in stressed cattle and the level of certain minerals may need to be increased to compensate for the low feed intake. Furthermore, nutritional status of calves prior to weaning and shipping may greatly influence health problems shortly after shipping. Calves deficient or marginally deficient in certain trace elements are likely to be more susceptible to infectious diseases.