title: An assessment of dairy herd bulls in southern Australia: 2. Analysis of bull- and herd-level risk factors and their associations with pre- and postmating breeding soundness results.
abstract: In pasture-based, seasonally calving dairy herds of southern Australia, the mating period usually consists of an initial artificial insemination period followed by a period of natural service using herd bulls. The primary objective of this study was to identify associations between individual bull- and herd-level management factors and bull fertility as measured by a pre- and postmating bull breeding soundness evaluation (BBSE). Multivariable mixed effects logistic regression models were used to identify factors associated with bulls being classified as high risk of reduced fertility at the premating and postmating BBSE. Bulls older than 4 yr of age at the premating BBSE were more likely to be classified high risk compared with bulls less than 4 yr of age. Bulls that were in herds in which concentrates were fed before mating were more likely to be classified as high risk at the postmating BBSE compared with bulls that were in herds where concentrates were not fed. Univariable analyses also identified areas in need of further research, including breed differences between dairy bulls, leg conformation and joint abnormalities, preventative hoof blocking for bulls, and mating ratios.
authors.affiliation: Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Werribee, Victoria 3030, Australia; The Vet Group, Timboon, Victoria 3268, Australia. Electronic address: a_s_hancock@hotmail.com.
authors.forename: A S
authors.initials: AS
authors.lastname: Hancock
authors.affiliation: The Vet Group, Timboon, Victoria 3268, Australia.
authors.forename: P J
authors.initials: PJ
authors.lastname: Younis
authors.affiliation: Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Werribee, Victoria 3030, Australia.
authors.forename: D S
authors.initials: DS
authors.lastname: Beggs
authors.affiliation: Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Werribee, Victoria 3030, Australia.
authors.forename: P D
authors.initials: PD
authors.lastname: Mansell
authors.affiliation: Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Werribee, Victoria 3030, Australia.
authors.forename: M A
authors.initials: MA
authors.lastname: Stevenson
authors.affiliation: Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Werribee, Victoria 3030, Australia.
authors.forename: M F
authors.initials: MF
authors.lastname: Pyman
mesh_terms: D000818:Animals; D001947:Breeding / Q000379:methods*; D002417:Cattle / Q000502:physiology*; D003430:Cross-Sectional Studies; D003612:Dairying / Q000379:methods*; D005298:Fertility; D016015:Logistic Models; D008297:Male; D012307:Risk Factors; D014739:Victoria
keywords: bull breeding soundness evaluation; dairy herd bull; lameness; seasonally calving herd