Evaluating results of pre-breeding reproductive examinations in yearling and mature beef bulls via the BullTest data reporting system

Abstract Text: Over a two-year period data were collected to summarize incidence and reasons for failure of reproductive soundness examinations in yearling and mature beef bulls.  Upon completion of examinations, participating veterinarians completed the BullTest card by indicating the number of yearling and mature bulls evaluated and the number of bulls in each age class that failed the examination.  Examinations were further classified by indicating number of bulls failing for each of the following reasons: semen motility, semen morphology, excess white blood cells present in ejaculate, penile injury/defects, wart proliferation, feet & leg conformation, scrotal circumference, and “other”.  In addition, practitioners indicated the type of examination conducted; simple semen exam or full breeding soundness exam (BSE), whether the test was for a breeding herd or production sale, and whether the test was the initial evaluation of bulls or a retest. Data were reported by 5 veterinary clinics and included 14,698 bulls in 1,374 groups.   Number of bulls reported in each group ranged from 1 to 228 (mean = 10.7 ± 0.43; median = 6).  For each group, proportion of bulls failing examination and proportion of bulls failing for each specific reason were calculated. Overall failure rate for groups of yearling bulls (22.1 ±1.2%) was greater (P < 0.01) than that of mature bulls (11.6 ± 0.8%).  A greater (P < 0.01) proportion of yearling bulls that were presented for retesting (39.5 ± 3.6%) failed examinations compared with those presented for their initial examination (18.2 ± 1.8%).  Similarly, a greater (P < 0.01) proportion of mature bulls that were presented for retesting (38.6 ± 2.7%) failed examinations compared with those presented for their initial examination (9.4 ± 0.7%).  Failure rates were similar (P = 0.62) among groups of yearling bulls tested as part of a breeding herd (20.9 ± 18%) or production sale (23.9 ± 2.6%). A greater (P ≤ 0.02) proportion of yearling bull failures were related to semen morphology or penile warts compared with mature bulls, whereas a greater (P< 0.01) proportion of mature bull failures were related to other penile injuries/defects or issues with feet and leg conformation.  The BullTest system provided an excellent platform to summarize results of pre-breeding reproductive evaluations in beef bulls.

Keywords: breeding soundness examinations, bulls, reproductive management