Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 10/1/1998
Publication Date: N/A
Technical Abstract: Breeding soundness examination (BSE) has not been previously described for reproductive system evaluation of bison bulls. In this multi-year cross- sectional clinical procedure evaluation, BSEs were performed on 234 28- to 30-month old bison bulls which were candidates for herd replacement or public sale at Custer State Park from 1993 through 1997. The 1992 Society for Theriogenology guidelines for beef bulls were used for semen evaluatio and reproductive tract examination. Linear and logistic regression were used to detect correlations and associations among BSE variables. Scrotal circumference (SC) was significantly correlated with body weight, percent normal sperm, percent primary sperm defects, and percent sperm motility. Increasing SC was positively associated with increased odds of semen collection, satisfactory motility (>= 30% motility), satisfactory morphology (>=70% normal sperm), and simultaneous satisfactory motility and dmorphology. Sperm morphology (especially mid-piece, tail, and separated head sperm defects) was associated with sperm motility. Receiver-operator characteristic curve analysis selected 29 cm as the optimal SC cutoff most predictive of simultaneous satisfactory sperm motility and semen morphology. Only 36.2% of the bison bulls had satisfactory sperm motility, sperm morphology and a SC of 29 cm or greater. We recommend use of 30% sperm motility, 70% normal sperm morphology, and 29 cm SC as minimal satisfactory measurements for BSEs on bison bulls 28 to 30 months of age which have been developed on forage-based nutrition.