The objectives of this study were to evaluate the prevalence of chronic Anaplasma marginale infection in beef bulls from eastern Kansas and compare breeding soundness parameters between A marginale–infected and uninfected bulls. We hypothesized that bulls with chronic anaplasmosis would have inferior breeding soundness exam (BSE) outcomes as a result of persistent A marginale infection or the consequence of initial clinical disease compared to uninfected bulls.
535 client-owned beef bulls from eastern Kansas undergoing routine BSE.
Complete BSEs were conducted by participating veterinarians according to the second edition of the Society for Theriogenology Manual for Breeding Soundness Examination of Bulls. Blood samples were collected for PCV determination and analysis of A marginale infection status via quantitative PCR and cELISA. Logistic and linear regression methods were used to evaluate factors associated with A marginale infection status and BSE parameters.
Prevalence of chronic A marginale infection was 46% (245/535) among bulls. Unsatisfactory BSE outcome was not statistically associated with chronic anaplasmosis in this study population, although more bulls with chronic anaplasmosis had unsatisfactory BSE outcomes (15.0 ± 2.4% vs 12.0 ± 2.2%).
Chronic anaplasmosis is prevalent among eastern Kansas breeding bulls; however, no negative association between chronic anaplasmosis and breeding soundness at time of BSE was observed.