Relationship of breeding soundness evaluation score and its components with reproductive performance of beef bulls

Angus, Polled Hereford and Santa Gertrudis bulls were subjected to a breeding soundness evaluation (BSE) just prior to being exposed to cows for 90 to 95 days in single-sire units under natural breeding conditions on pasture. Forty-eight of 55 bulls subjected to scrotal and semen evaluations passed the BSE and were considered acceptable for breeding. Of the bulls that passed BSE, 18 (six bulls from each breed) were used for breeding for each yr of the 2-yr study. Of the bulls used for breeding, breed of sire differences were significant for scrotal circumference and calving rate, while differences among sires within breed of sire were significant for secondary morphology, motility score and calving rate. The difference between means for bulls used vs bulls that failed BSE was significant for all eight traits. Correlations among various scrotal and semen evaluations were compared for bulls used vs bulls that failed BSE. Of the eight traits, only the motility score was significantly correlated with the calving rate. After the exclusion of bulls that failed to pass BSE, there remained differences (P<0.01) among bulls within breed of sire for calving rate. Thus, there is a need for an additional easy-to-use procedure that would more accurately predict the breeding performance of bulls.