Cobalt supplementation affects humoral immune response in beef calves
Sager, Robert Bascom
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Economic losses from morbidity and mortality associated with bovine respiratory disease (BRD) in beef cattle are approaching $2 billion annually in the United States. Incidence and severity of BRD is increasing despite advances in animal health programs in prevention and treatment compared to twenty years ago. Mineral supplementation during pre-weaning has potential to reduce sickness and improve health. Cobalt (Co) is used by rumen-inhabiting microbes for the production of vitamin B 12. Vitamin B 12 is a cofactor for vital metabolic pathways in tissue carbohydrate and lipid metabolism required for maintenance and growth. Vitamin B 12 is also vital for B-cell proliferation to form plasma cells that secrete antibodies. National Research Council (NRC) recommendations for Co are 0.1 ppm (0.1 mg/kg; DM dry matter basis). Beef production has changed tremendously since NRC recommendations were set in the 1950's. The hypothesis of these three studies is NRC Co concentrations need to be increased to meet today's beef cattle metabolic requirements and production needs. The objectives of these studies were to evaluate if an orally-supplied Co dosed at nursing, pre-weaning, or post weaning affects humoral immune response during the post-weaning feeding period and reduces the incidence of BRD. Mannheimia haemolytica is a major pathogen of BRD which causes increased pathophysiological pulmonary tissue severity, increased treatment time, and increased mortality in beef calves. Calves were vaccinated with M. haemolytica in all studies as an indicator of immune response. Different dosages and forms of Co were administered to evaluate humoral immune response. Results indicate increased NRC Co concentrations affect humoral immune response and potentially improve beef calf health. Study results suggest current NRC Co concentrations should be increased to improve post-weaning health in beef calves.