The impact that nutrition has on a properly functioning immune system is multiplied in cattle due to production systems that could cause nutritional deficiencies or toxicities in large groups of cattle, rather than in an individual animal. Since nutrition has such a big influence on proper immune system function, understanding the impact various nutrients can have on the immune system is important for understanding the potential for immune system failure in production animals. The nutritional status of cattle requires appropriate feed intake and proper supplements matched to the animal’s production use, physiological condition, overall health, and reproductive status, and balanced with the feed, all of which can influence the function of the immune system. Therefore, bovine veterinary practitioners must consider energy balance, protein, trace minerals, and vitamin status that may affect the animal’s immune response.