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

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Presentation on theme: "Reproductive Management of Herd Sires By Paul Coe, DVM Michigan State University."— Presentation transcript:

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

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 Frame2400 0132 lb.early vegetative grass Continental Moderate Frame2000 0110 lb.early vegetative grass English Large Frame1500 2 lb./day56 lb. Grass + 12 lb. Corn Yearling Moderate Frame1500 2 lb./day67 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 Bull to Cow Ratio Guidelines 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 1:60 1:35 1:40 *Using bulls that passed BSE


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