The Immune System and Recovery From Sickness in Cattle

Ideally, all diseases could be prevented and beef animals on-feed would finish healthy and with the highest quality of meat. That isn’t realistic for most diseases. In spite the best efforts, some animals will become sick and require treatment. Calves with bovine respiratory disease (BRD) that required more than one treatment had decreased quality of meat and economic returns than did calves that did not develop BRD or responded after one treatment. (Hicks, 2006; McNeill, 1999; Wagner, et al., 2006) Calf-hood diseases in heifer calves had measurable effects on maternal performance for several years. (Waltner-Toews et al., 1986; van der Fels-Klerx et al., 2002) Those data suggest that health of young stock (whether intended to be replacement brood-stock or for meat) deserves attention. With understanding of the diseases, response to treatment and the role of the immune system, appropriate expectations can be developed and improvements can be made where possible. When an animal becomes sick, one or more factors of its immune system have not performed adequately. The mission of treatment for that animal is to support its immune system and allow the animal to regain its health so it can reach its genetic and nutritional potential. Appropriate selection and use of medication is one tool for treatment, but that medication does not replace the animal’s immune system. Clinical response to treatment involves well orchestrated cooperation of the animal’s immune system, nutrition and medication. Tremendous advances have been made to understand the immune system, the importance of proper nutrition and the use of effective animal health products to enhance production of beef. Even the most prepared host defenses can be overwhelmed. Detection of sick animals, provision of appropriate nutrition, and proper application of animal health products remain part of the “human element” of managing animal health. Anything humanly possible that can be done to enhance the animal’s immune function and reduce exposure to infectious agents will reduce the animal’s risk of becoming sick as well as enhance its chances of recovery when treatment becomes necessary