Prevalence of morphologic defects in spermatozoa from beef bulls

K. R. Johnson, C. E. Dewey, J. K. Bobo, C. L. Kelling, D. D. Lunstra

Research output: Contribution to journalArticlepeer-review

21 Scopus citations


Objective - To determine the overall prevalence of morphologic defects in spermatozoa from beef bulls and to determine whether prevalence varies with the age of the bull. Design - Cross-sectional observational study. Animals - 2,497 beef bulls that were evaluated for breeding soundness in 1994 by 29 practicing veterinarians in a 5-state geographic region. Procedure - Slides of spermatozoa from each bull were made and submitted by practicing veterinarians for morphologic evaluation. One hundred spermatozoa per slide were examined, and each was classified as having 1 of 9 morphologic defects or as normal. Results - 63% of bulls evaluated were 10 to 12 months old, and 20% were 13 to 18 months old. A mean of 70.6% of spermatozoa was classified as normal. Most common defects were proximal droplets (8.4%), distal midpiece reflexes (6.7%), separated heads (5.5%), and distal droplets (3.8%). Other defects were seen < 2% of the time. Bulls 10 to 12 months of age had a higher prevalence of proximal and distal droplet defects than older bulls. Clinical Implications - Practitioners conducting breeding soundness evaluations in beef bulls must be aware of common spermatozoal defects. Bulls that are evaluated at a young age will have more defects than older bulls and should be reevaluated, particularly for those defects for which prevalence decreases with age.

Original languageEnglish (US)
Pages (from-to)1468-1471
Number of pages4
JournalJournal of the American Veterinary Medical Association
Issue number10
StatePublished - Nov 15 1998

ASJC Scopus subject areas

  • General Veterinary


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