Trace Mineral Nutrition of Grazing Beef Cattle

SIMPLE SUMMARY: The trace mineral nutrition of grazing beef cattle is an essential, but often complicated component of the management program. Throughout the annual cycle, forage is the primary source of trace mineral supply to grazing cattle, but concentrations vary depending on a multitude of factors. Trace mineral deficiencies are common when relying solely on forage to meet cattle requirements. Selenium, Cu, Zn, Mn, Co, and I are the trace minerals most commonly found to be deficient in forage. Trace mineral antagonists, such as Fe, Mo, and S, are commonly found in forage and exist in varying concentrations further complicating the success of satisfying the requirement of grazing cattle. Trace mineral-fortified, salt-based, free-choice supplements are the most common supplementation strategies available. Cattle voluntarily consume these supplements to satisfy their salt craving and thus indirectly receive supplemental trace minerals. Managing salt inclusion and seasonal variation in voluntary intake are essential to the success of this management system. Supplements can be formulated with a variety of trace mineral ingredients available to the industry, which are generally grouped into different source categories. Other supplementation strategies to supply trace minerals to grazing cattle include fortification of energy and protein supplements, biofortification, injectable trace minerals, and boluses. ABSTRACT: The trace mineral requirements of grazing beef cattle are often complicated by different environmental factors, such as the lack of specific trace minerals or the presence of trace mineral antagonists in forage. Nearly every region of the world has specific implications related to trace mineral nutrition of grazing cattle. Since forage is the most significant contributor to trace mineral nutrition, it is important to consider the concentrations of trace minerals and antagonists and how they may impact the performance of cattle consuming them. This review attempts to provide an update on the trace minerals commonly found to be inadequate in forage, supplementation strategies to address deficiency including a discussion on supplemental trace mineral source, and the complications presented by mineral antagonists. Although the review focuses on beef cattle grazing systems of the United States, the information herein is derived from both extensive native range and intensive planted pasture.