Bull Breeding Soundness

Third Edition

June 2013

Albert D. Barth, DVM, MVet Sc Diplomate of the American College of Theriogenologists Professor of Large Animal Clinical Sciences Western College of Veterinary Medicine University of Saskatchewan Saskatoon, Saskatchewan, Canada

Published by the Western Canadian Association of Bovine Practitioners

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Contents Acknowledgements ...... vi Preface ...... 1 Introduction ...... 2

I. THE BREEDING SOUNDNESS EVALUATION FORM ...... 4 II. SERVICE CAPACITY ...... 9 1. Introduction ...... 9 2. Methods of testing service capacity ...... 10 3. Breeding crates ...... 12 III. PHYSICAL SOUNDNESS ...... 14 1. General health ...... 14 2. Body condition ...... 14 3. Eye problems ...... 15 4. Foot and leg problems ...... 16 5. Examination of the scrotum and its contents ...... 18 a) Restraint b) Scrotal shape and scrotal abnormalities c) Scrotal frostbite d) Palpation of the scrotum and its contents 6. Scrotal circumference (SC) ...... 23 a) The relationship of SC to fertility b) Effects of nutrition c) Effect of breed d) Technique of SC measurement e) Sources of error in SC measurements 7. Transrectal internal examination ...... 29 8. Examination of the penis and prepuce ...... 31 IV. SEMEN COLLECTION ...... 34 1. Semen collection by electroejaculation ...... 34 a) Equipment b) Restraint c) Stimulation technique 2. Factors affecting semen collection ...... 36 a) Electroejaculation technique b) Effectiveness of electroejaculation equipment c) Individual bull response to stimuli d) Disturbances of testicular or epididymal function

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3. Collection by transrectal massage ...... 37 4. Collection by artificial vagina ...... 37 5. Collection with an internal artificial vagina ...... 37 6. Collection by vaginal aspiration ...... 38 V. EVALUATION OF SEMEN QUALITY ...... 40 1. Microscopy ...... 40 a) Kinds of light microscopes b) Alignment and care of microscopes 2. Semen density and volume ...... 41 3. Sperm viability ...... 41 a) Gross motility b) Individual motility, dilution methods c) Vital staining 4. Sperm morphology ...... 43 a) Preparation of semen smears b) Preserving semen samples c) Artifacts, contaminants and debris in semen smears d) Differential counting and recording of sperm abnormalities e) Classification of sperm abnormalities f) Tolerance levels for sperm abnormalities g) Classification of breeding soundness h) Decision deferred bulls VI. SPERM STRUCTURE ...... 50 Types of sperm abnormalities VII. PHOTOGRAPHIC CATALOG OF SPERM ABNORMALITIES ...... 53 VIII. SPERM ABNORMALITIES: A REVIEW ...... 70 1. Pyriform heads and tapered head ...... 70 2. Microcephalic and macrocephalic sperm ...... 71 3. Nuclear vacuolation ...... 72 4. Abnormal DNA condensation ...... 75 5. Detached head ...... 76 6. The Decapitated sperm defect ...... 77 7. Rolled Head-Nuclear Crest-Giant Head Syndrome (RCGH) ...... 77 8. Sperm accumulation ...... 77 9. Azoospermia/Oligospermia ...... 78 10. Knobbed acrosomes ...... 79 11. Distal midpiece reflex (DMR) ...... 81 12. Segmental aplasia and midpiece fracture ...... 83

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13. Abaxial and Accessory tails ...... 84 14. Dag defect ...... 84 15. Tail stump defect ...... 85 16. Corkscrew defect ...... 85 17. Pseudodroplet defect ...... 86 18. Coiled principal piece ...... 86 19. Short tail defect ...... 87 20. Proximal cytoplasmic droplets ...... 87 21. Distal cytoplasmic droplet ...... 88 22. Sperm agglutination and antisperm antibodies ...... 89 IX. DEVELOPMENT OF SPERM ABNORMALITIES ...... 97 1. Normal spermatogenesis ...... 97 2. Abnormal spermatogenesis ...... 98 3. Classification of sperm abnormalities ...... 104 4. Interpretation of sperm morphology counts ...... 105 X. PUBERTAL DEVELOPMENT ...... 108 1. Developmental changes in the testes ...... 108 2. Relationships of age and puberty ...... 108 3. Effect of nutrition on sexual development ...... 109 a) Effect of postweaning nutrition b) Effect of calfhood nutrition c) Effect of breed on onset of puberty d) Effect of season on onset of puberty e) Relationship of SC and puberty f) Selection of bulls at weaning g) Selection of bulls at one year of age

XI. CONGENTIAL ABNORMALITIES OF THE GENITAL TRACT ...... 119 1. Congenital conditions of the Testes and Scrotum ...... 119 a) Testicular Hyperplasia b) Testicular Hypoplasia c) Klinefelter's Syndrome d) Effect of a female co-twin on bull fertility e) Cryptorchidism f) Scrotal or Inguinal Hernia g) Ectopia Testis h) Short scrotum, Caudal frenulum of the scrotum, Rotated scrotum i) Vascular Malformation of the spermatic cord

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2. Congenital conditions of the efferent ductules, epididymis and accessory glands...... 122 a) Bind-ending efferent ductules b) Epididymal aplasia c) Cystic appendix epididymis d) Hypoplasia and aplasia of the vesicular glands e) Prostatic and bulbourethral gland cysts 3. Congenital conditions of the penis and prepuce ...... 125 a) Deviations of the penis b) Congenitally short penis c) Persistent frenulum d) Hypospadia e) Eversion of the prepuce

XII. ACQUIRED ABNORMALITIES OF THE GENITAL TRACT ...... 132 1. Testicular degeneration ...... 132 2. Testis fibrosis ...... 133 3. Orchitis ...... 135 4. Testicular neoplasia ...... 136 5. Scrotal hydrocele and hemocele ...... 136 6. Penile hematomas ...... 136 7. Preputial injuries ...... 138 a) Fresh lacerations b) Laceration with prolapse c) Laceration with phimosis d) Laceration with paraphimosis e) Circumferential lacerations f) Laceration with phimosis and abscessation g) Laceration with ventral abdominal cellulitis 8. Penile papillomas ...... 144 9. Inflammatory conditions of the accessory sex glands ...... 146 a) Vesicular adenitis b) Epididymitis 10. Hemospermia ...... 148 XIII. MANAGEMENT OF BEEF BULLS ...... 152 1. Rearing bulls for fertility ...... 152 2. Use of yearling bulls ...... 153 3. Management of 2-year-old and older bulls ...... 154 4. Effect of bull to female ratio on fertility in pasture breeding ...... 156

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5. Effect of service capacity on fertility ...... 158 6. Effects of social dominance order on fertility ...... 158 7. Postpartum exposure of cows to bulls to shorten postpartum anestrus ...... 160

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Acknowledgments

The author is greatly indebted to the following reviewers for the time and effort to ensure that this manual correctly reflects the scientific literature and the views of veterinarians across Canada.

Dr. Bronwyn Crane Department of Health Management, Atlantic Veterinary College Charlottetown, Prince Edward Island

Dr. Craig Dorin Veterinary Agri-Health Services Ltd. Airdrie, Alberta

Dr. Walter Johnson Department of Population Medicine, Ontario Veterinary College Guelph, Ontario

Dr. John Kastelic Department of Production Animal Health, University of Calgary Faculty of Veterinary Medicine, Calgary, Alberta

Dr. Denis Vaillancourt Département de médecine, Faculté de médecine vétérinaire Saint-Hyacinthe, Quebéc

Phyllis Mierau Western Canadian Association of Bovine Practitioners (WCABP) Saskatoon, Saskatchewan