Factors associated with yearling bulls passing subsequent breeding soundness evaluations after failing an initial evaluation

Abstract

Abstract OBJECTIVE To determine the proportion of yearling beef bulls classified as satisfactory potential breeders when reevaluated after failing an initial breeding soundness evaluation (BSE) and identify any factors at initial BSE that predicted satisfactory performance at reevaluation. DESIGN Retrospective observational study. ANIMALS 2,064 beef bulls between 11 and 14 months of age at first BSE, evaluated from 2006 to 2014. PROCEDURES For each bull, data on age (categorized by month), breed, and BSE findings were extracted from the medical records. Bulls were classified as satisfactory potential breeders if they met Society for Theriogenology standards at the initial BSE or up to 2 subsequent reevaluations. Generalized linear mixed models were generated to assess potential associations between certain variables at initial BSE and passing that evaluation or passing subsequent BSEs after initial failure. RESULTS 1,921 of 2,064 (93.1%) yearling bulls passed 1 of up to 3 BSEs. The proportion of yearling bulls that were not classified as satisfactory during initial BSE but were later classified as satisfactory was 143 of 287 (49.8%). A significant interaction was identified between bull age and breed in the probability of passing the initial evaluation. No variable, including breed, age, scrotal circumference per day of age, and spermatozoa morphology at initial BSE, significantly predicted passing subsequent reevaluations after failing an initial BSE. CONCLUSIONS AND CLINICAL RELEVANCE Age and breed information should be considered when deciding the age at which initial BSE should be scheduled for a yearling bull cohort.