Factors Affecting Antibody-Mediated Immune Response and Cellular-Mediated Immune Response in Weaned Brahman Calves

Selecting high-immune-responding cattle benefits the individual animal and the herd. To assess factors that have a role in determining the immune status of cattle, this study used 55 weaned bull and 57 weaned heifer Brahman calves. Antibody-mediated immune response (AMIR) was determined by using a vaccine-specific IgG, enzyme-linked immunosorbent assay (ELISA) in response to cattle receiving the Salmonella Newport Extract vaccine. Cell-mediated immune response (CMIR) was determined by using a subcutaneous (neck) sensitization dose of Candida albicans (CA) with Quil-A adjuvant on Day 0. On Day 14, caudal skinfold thickness (SFT) was measured using Harpenden calipers prior to the intradermal injection of CA into the skinfold, and on Day 15, the injection site SFT was measured again. The response was determined by using the difference in SFT from Day 15 (post-injection) and Day 14 (pre-injection). In weaned Brahman calves, AMIR was not influenced by sex; however, there was sexual dimorphism associated with CMIR, in that bull calves had a greater response than heifers (p < 0.05). Our studies demonstrate that weaned Brahman calves can be separated into AMIR and CMIR classes and that AMIR and CMIR should be investigated further as selection tools in beef cattle production.