Effect of cobalt supplementation on humoral immune response in weaned beef calves

摘要

The National Research Council (NRC) requirements for cobalt (Co) (0.1 mg/kg or 0.1 ppm; DM intake) were first published in the 1950s when production expectations for beef cattle production were two-thirds as great as present-day production expectations. Recommended NRC Co requirements were derived during the 1950s from experiments with cattle that were genetically different, fed different rations, and raised with different production and economic expectations compared with cattle today. Compared withtheir 1950s counterparts, today's beef cattle are 35 to 40% larger anatomically, grow at increased rates, and were genetically selected for maximum muscle growth. Rumen microbial organisms use Co for the synthesis of vitamin B_(12), which is a necessarycofactor for vital metabolic pathways in lipid and carbohydrate energy metabolism. In the past, studies have focused on the effect of Co supplementation on performance and growth. The objective of this study was to evaluate supplementation of weaned beef calves with 3 levels of Co on humoral immune response to Brucella abortus vaccination.