Bovine Reproduction

1 Cover

2 Series Page “Let our cattle bear, without mishap and without loss” Psalms 144:14, New American Standard Bible

3 Title Page

4 Copyright Page

5 Dedication Page

6 List of Contributors

7 Preface and Acknowledgments to the Second Edition

8 Preface and Acknowledgments to the First Edition

9 About the Companion Website

10 Section I: The Bull

11 Anatomy and Physiology 1 Anatomy of the Reproductive System of the Bull Introduction Production Transport Transfer References 2 Endocrine and Exocrine Function of the Bovine Testes Introduction Historical Perspective The Testis The Scrotum and Spermatic Cords Interstitial Tissue (Leydig Cells) Endocrine Function of the Testis Overview of Spermatogenesis and Maturation of Spermatozoa References 3 Spermatogenesis Introduction Cell and Molecular Biology of Spermatogenesis Markers to Study Spermatogenesis Hormones and Spermatogenesis The Cycle of the Seminiferous Epithelium Spermatogenesis in the Bull Sertoli Cells and Spermatogenesis The Role of Sertoli Cells in Spermatogenesis References 4 Thermoregulation of the Testes Introduction Anatomy and Physiology Surface and Internal Temperatures Sources of Testicular Heat Effects of Increased Testicular Temperature Summary References 5 Endocrine Control of Testicular Development and Initiation of Spermatogenesis in Bulls Introduction Infantile Period Prepubertal Period Pubertal Period Metabolic Hormones During the Prepubertal and Pubertal Periods References 6 Sexual Development and Puberty in Bulls Introduction Testicular Development Puberty Development of Accessory Sex Organs Development of Sexual Behavior Effects of Nutrition on Sexual Development Implications of Sexual Development and Puberty for Breeding Soundness Evaluation References

12 Breeding and Health Management 7 Breeding Soundness Evaluation: Comparative Review of Different Standards Introduction General Concepts An International Overview of BBSE BBSE – How the Categories Compare Internationally Discussion References 8 Evaluation of Breeding Soundness: The Physical Examination Introduction History Basic Physical Examination Examination of the Reproductive System Example of an Examination Protocol Scrotal Circumference References 9 Evaluation of Breeding Soundness Introduction Semen Collection Semen Evaluation References 10 Ultrasound Examination of the Reproductive Tract Introduction Equipment and General Methodology Examination of the Scrotum Examination of the Pelvic Organs Examination of the Penis and Prepuce Alternative Ultrasound Modalities Summary References 11 Management of Breeding Bull Batteries Introduction Pre‐Breeding Period Breeding Period Non‐Breeding Period References 12 Management of Bulls at Custom Collection Studs Veterinary Services for the Commercial Bull Stud Common Problems of Bulls at Stud Summary Acknowledgment 13 Testicular Degeneration Introduction Pathogenesis Diagnosis Prognosis Testicular Fibrosis References 14 Vesicular Adenitis References 15 Inability to Breed Due to Injury or Abnormality of the External Genitalia of Bulls Introduction Impact of Impotence Physiology of Erection in the Ruminant Coitus Abnormalities of the Prepuce Abnormalities of the Penis Penile Injury Erection Failure Denervation Injury References 16 Management of Lameness in Breeding Bulls Introduction Getting Back to Basics in a Lameness Examination Facilities for Performing the Lameness Examination Local/Regional Anesthesia Back Injuries Advanced Diagnostics Laminitis Treatment of Solar Injuries Vertical Hoof Cracks Septic Arthritis of the Distal Interphalangeal Joint Corkscrew Claw Interdigital Dermatitis, Digital Dermatitis, and Interdigital Pododermatitis Interdigital Fibroma Distal Limb Proximal Limb Upward Fixation of the Patella Rupture of the Gastrocnemius Osteochondrosis Dissecans Bone Fractures Full Limb Casting Fractures of the Proximal Limb Fracture Recovery Hoof Trimming for Beef Cattle Summary References

13 Reproductive Surgery 17 Regional Anesthesia for Urogenital Procedures Introduction Local Anesthetics Anesthesia for Laparotomy Anesthesia of the Perineum Anesthesia of the Penis and Prepuce Anesthesia for Castration References 18 Surgery of the Scrotum and its Contents Introduction Physical Examination of the Scrotum and Testicles Ultrasound of the Testicles Thermography of the Scrotum Semen Evaluation Scrotal and Testicular Disease and Injury Unilateral Castration Inguinal Hernia Repair References 19 Restorative Surgery of the Prepuce and Penis Introduction Fibropapilloma Hair Ring Persistent Frenulum: Delayed Preputial–Penile Separation Preputial Injury Preputial Prolapse Surgical Management of Preputial Injury Phimosis Paraphimosis Hematoma Penile Deviations References 20 Management of Urolithiasis Introduction Clinical Signs Diagnosis Treatment Surgical Management Other Procedures Prevention References 21 Preparation of Teaser Bulls Introduction Vasectomy Epididymectomy Penile–Prepuce Translocation Penopexy Preputial Pouch Technique (Ventral Slot with Preputial Orifice Obliteration) Other Procedures Summary References

14 Section II: The Cow

15 Anatomy and Physiology 22 Anatomy of the Reproductive System of the Cow Introduction Production Transport and Gestation Blood Supply Placenta References 23 Initiation of Puberty in Heifers Introduction Endocrine Events Development of the Female Reproductive Tract Factors that Influence Age of Puberty Genetic Markers for Age at Puberty Correlation Between Sire Scrotal Circumference and Age at Puberty of Daughters Management Options to Influence Age at Puberty Photoperiod Growth‐Promoting Implants Use of Progestins to Advance Onset of Puberty Nutritional Optimization of Puberty Effect of Heifer Temperament on Age at Puberty Influence of Bull Exposure on Age at Puberty Influence of Age of Dam on Follicular Reserves Monitoring Heifers for Attainment of Puberty References 24 Neuroendocrine Control of Estrus and Ovulation Introduction Functional Anatomy of the Hypothalamic–Hypophyseal Unit Hierarchical Control of Gonadotropin Secretion: The GnRH Pulse Generator Role of Gonadal Steroids Differential Control of Gonadotropins: FSH Nutritional Influences on the Hypothalamic–Hypophyseal Axis Pubertal Development Neuroendocrinology of the Postpartum Period Novel Neuroendocrine Regulators of GnRH Neuronal Function References 25 Ovarian Follicular and Luteal Dynamics in Cattle Introduction Ovarian Development and Follicle Assembly Folliculogenesis and Oogenesis Ovulation and Oocyte Maturation References 26 Maternal Recognition and Physiology of Pregnancy Introduction Conceptus Elongation and Extraembryonic Membranes Uterine Histotroph Placental Vascularization Maternal Cardiovascular Function Maternal Nutrient Partitioning and Endocrinology Embryogenesis, Fetal Growth, and Organ Development Uterine Blood Flow References 27 Fetal Programming Introduction Adaptations During Pregnancy: Fetal and Placental Development Maternal Nutrient Restriction Offspring Performance Maternal Melatonin Supplementation Epigenetics and Fetal Programming References

16 Breeding and Health Management 28 Biosecurity for Beef and Dairy Herds Introduction Developing a Biosecurity and Biocontainment Plan Tools for Intervention: Reducing Effective Animal Contacts Movement Control Barriers Special Considerations Summary References 29 Beef Heifer Development Introduction Replacement Heifer Economics Selection at Weaning Prebreeding Nutritional Management Prebreeding Selection and Management Breeding Season Management Postbreeding Through Calving Summary References 30 Dairy Heifer Development from Weaning to Calving Introduction The Weaned Heifer Summary References 31 Nutrition and Reproduction in the Beef Cow Introduction The 12‐Month Cow‐Calf Production Cycle – The Driver of Nutrient Requirements Body Condition Scoring