Prevalence of abnormalities in polled and horned bulls which may affect their breeding soundness

Summary

The major objective of this project was to evaluate the evidence of reported associations between specific abnormalities affecting bull breeding soundness (preputial prolapse, reduced serving capacity and premature spiral deviation of the penis (PSDP) and the polled condition.
The systematic review of published scientific literature and industry anecdote concluded that factors not likely to be related to the polled condition, such as sheath structure, probably have a greater influence on the occurrence of preputial prolapse than any negative effect of the polled condition. No evidence was found of a relationship between the polled condition and reduced serving capacity or libido.
The systematic review found that PSDP was likely to be heritable, but there was no evidence it was directly associated with the polled condition. Analysis of serving ability/capacity data from bull breeding soundness data bases provided by 3 veterinary practices and 2 beef cattle researchers confirmed previous reports that the prevalence of PSPD increases with age, being markedly greater in bulls ≥ 3 years of age. For bulls ≥3 years of age approximately twice as many cases of PSPD were detected in polled-breed bulls (13.5%; n=496) than in horned-breed bulls (5.6%; n=233), clearly indicating that it is a much greater problem in polled-breed bulls but occurs frequently enough in horned-breed bulls to suggest that it is unlikely to be simply associated with the polled gene.
With the likely greater use of polled-breed bulls in beef herds, producers of polled-breed bulls should be encouraged to conduct serving capacity tests on their ≥ 3-year old herd sires to identify those affected with PSPD. Further, with the support of relevant breed societies and geneticists, strategies which may include the use of DNA marker technology should be established to enable seedstock producers to select against this problem.