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Reproductive Management of Herd Sires

Reproductive Management of Herd Sires. By Paul Coe, DVM Michigan State University. Basic Needs. Nutrition Shelter Exercise Medical Care Breeding Management. Nutrition. NRC recommendations provide a guideline Modify diet based on BCS Bulls have two nutritional seasons

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Reproductive Management of Herd Sires

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  1. Reproductive Management of Herd Sires By Paul Coe, DVM Michigan State University

  2. Basic Needs • Nutrition • Shelter • Exercise • Medical Care • Breeding Management

  3. Nutrition • NRC recommendations provide a guideline • Modify diet based on BCS • Bulls have two nutritional seasons • Breeding season: maintenance + increased activity • Post-breeding: maintenance + reconditioning • Need to start the breeding season at BCS 5 to 6 • Variation either way reduces libido and fertility (% normal sperm)

  4. Condition Score >6 6 5 4 <4 Barling,Wilkes et.al1995 % Passing 62 67 72 70 55 Body Condition Score and BSE Pass Rate

  5. Diet During Breeding Season • Grass • Limiting Nutrients • Fiber (based on 30% dry matter in pasture) • Crude Protein • Phosphorous

  6. How Much Grass Does A Bull Need? TypeWt.ADGMaintenance Diet Large Frame 2400 0 132 lb.early vegetative grass Continental Moderate Frame 2000 0 110 lb.early vegetative grass English Large Frame 1500 2 lb./day 56 lb. Grass + 12 lb. Corn Yearling Moderate Frame 1500 2 lb./day 67 lb. Grass + 10 lb. Corn Yearling

  7. How Much Grass Will A Bull Eat? • Varies with availability and quality • 75% variation due to availability • 25% variation due to quality • 2% of body wt. in dm.needed for maint. • 2400 lb. Large frame bull • 2400x.02=48 lb./.3(dm in grass)=160 lb. of pasture • 3% of body wt. In dm.needed for av.growth • 1500 lb. Yearling bull gaining 2 lb./day • 1500x.03=45 lb./.3(dm in grass)=150 lb. of pasture

  8. The Question • Does a good bull take the time to eat that much grass when he is checking for heat and breeding cows?

  9. The Answer • Bulls often lose 1 to 2 body condition scores (160 to 200 lbs) during a breeding season • Under extensive or rotational grazing management, grass does not stay in the early vegetative state over the breeding season (so consumption goes down). • The answer is NO.

  10. Diet During the Off Season • Mature Bulls • Regain lost weight • Regain BCS 5 to 6 through the winter • Yearling Bulls • Additional growth • Typical Feeds • Hay and/or silage, grain, mineral.

  11. How much feed does a bull need when he is not breeding cows? • 270 day feeding period, some cold stress, BCS 4 • Large frame mature bull (2400 lb.BCS 5-6) • 30 lb.grass hay + 9 lb. sh.corn to gain 1 lb./day • Moderate frame mature bull (2000 lb.BCS 5-6) • 23 lb.grass hay + 9 lb. sh.corn to gain 1 lb./day • Large frame yearling (from 1400 lb.to 2000 lb.) • 9 lb.grass hay + 19 lb. sh.corn to gain 2.1 lb./day • Moderate frame yearling bull (1400 lb.to 1800 lb.) • 16 lb.grass hay + 12.5 lb sh.corn to gain 1.5 lb./day

  12. Feeding Bulls • Assess BCS following breeding season • Analyze available feeds • Plan a ration that should have bulls at BCS 6 for breeding season • Monitor body condition and adjust ration • Hand feeding during breeding season • Allows daily observation and makes bulls easier to manage

  13. Whole Cottonseed • Contains gossypol, a toxin that impairs sperm production • Limit cottonseed to 4 lb./head/day • Add 4000 IU of vitamin E/head/day to neutralize the effects of gossypol.

  14. Shelter • Well fed bulls do not need much shelter • Windbreak • Access to sod/dirt lot improves foot health • Mud and concrete = feet and leg problems

  15. Exercise • Maintains physical conditioning for breeding season. • 2 acres per bull. • Feed and water spaced apart so that bulls have to walk daily.

  16. Routine Health Care • Observe frequently during breeding season • Mating ability • Injuries – diagnose and correct promptly • Close exam at end of each breeding season • Injuries • Body Condition Score • Culture for Trichmoniasis

  17. Breeding Soundness Exam • Rigorous exam at purchase • Annual examinations • Aid culling decisions • Prognosis based on evidence of testicle damage seen in sperm morphology

  18. Disease Control • Vaccination program same as cows • IBR, BVD, Leptospirosis • Local diseases (Clostridia) • Herd problems (Campylobacter, H. somnus) • Avoid MLV in bulls collected for A.I. Or within 30 days of breeding season • Parasite control • Deworm with cows • Control liver flukes, if problem exists in herd • External parasites in the fall

  19. Breeding Season Management • Start with bulls that pass a BSE • Large testicles increase serving capacity • Libido and ability to mate • Serving capacity test • Observation • % calf crop attributable to each bull

  20. Breeding Plan Yearling bull,Conventional Mating Estrus Synch. with natural service Cleanup following A.I. ** Rugged terrain, low stocking rate Mature bull, conventional mating **Assumes AI conception >60% Ratio* 1:25 1:25 1:60 1:35 1:40 *Using bulls that passed BSE Bull to Cow Ratio Guidelines

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