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Breeding Beef Cattle

Breeding Beef Cattle. Agriculture II. Objectives:. Recite the time of the average estrus cycle and gestation period Explain advantages and disadvantages of A.I. and natural service Explain tests for Breeding Soundness Exam State ideal stocking rate for bull:cow ratio

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Breeding Beef Cattle

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  1. Breeding Beef Cattle Agriculture II

  2. Objectives: • Recite the time of the average estrus cycle and gestation period • Explain advantages and disadvantages of A.I. and natural service • Explain tests for Breeding Soundness Exam • State ideal stocking rate for bull:cow ratio • Discuss the importance/advantages of a controlled breeding season • Explain nutritional requirements for proper fetal growth • Define and explain reasons for calving difficulty • Describe steps that occur during postpartum anestrus • Explain a typical breeding season cycle

  3. Facts and Terms • Gestation period: 283 days • Estrus period: 21 days • Dystocia – birthing difficulty • Replacement heifer – a heifer that is kept in the herd at puberty for the purpose of reproduction (replacing older/nonproductive cows) 283 day gestation 283 day gestation Reach puberty 10-14 months Replacement Female 1st calf @ age 2 Birth (70 lbs) Breed Breed

  4. Artificial Insemination vs. Natural Service • Advantages of A.I. • Genetic improvement (BIGGEST) • Reduce bull maintenance • Decrease venereal disease risk (minor) 2. Disadvantages of A.I. • More labor intensive (BIGGEST) – checking heat • Skill required – A.I. Technique • May be lower conception rate • 5-15% advantage in natural service

  5. Combining A.I. and Natural Service Breeding Season • Breed with A.I. the first time • With or without using estrus synchronization (drug to make cow come into heat) 2. Complete season with bulls Use A.I. May 1-5 synchronized Use “clean-up” bulls With synchronization Day 1 Day 23 Day 65 Day 44 Day 86 Use A.I. Without synchronization May 1-22 synchronized Use “clean-up” bulls Day 1 Day 22 Day 64 Day 43 Day 85

  6. Bull Management • Breeding Soundness Exam (BSE) – the best estimate of bull fertility • Physical Exam – overall health • Scrotal measurement – circumference (best estimate of daily sperm output; want greater than or equal to 32 cm at 1 year old • Semen quality – motility, morphology, concentration What’s the only thing you can’t test for?

  7. Stocking Rate(Bull to female ratio) • Common recommendation is 1:25-30 • 1 bull for every 25-30 females • This is typically an underestimate for an older/mature bull • For farms with multiple bulls – rotation every 21 days

  8. Controlled Breeding Season • REDUCES CALVING SEASON * • Produce a more homogeneous calf crop • more marketable • Easier to manage for replacement heifer • Can more efficiently manage herd – especially pregnant cows * Want calves born early because late calves are lighter and go for less at market

  9. Pregnancy • Pregnancy Check • Purpose is to avoid feeding cows with no economic return • Good time to check is 50 days into pregnancy which would be about the time the previous calf is weaned • Fetal growth – nutrition • Last 90 days gestation • Max fetal growth • Underfeeding = decrease in calf growth and decreased survival

  10. Calving(number 2 reduction in net calf crop) • Calving Difficulty = Dystocia • Deaths within the first 24 hours after birth • Fetopelvic Disproportion • Birth Weight - #1 cause • Selection of breed (ex. Angus) • Selection within a breed (EPD) • Age of Dam – 1st calf vs. later calves • Pelvic size (secondary cause) a. Large frame heifer = bigger pelvis; so we select the older bigger heifers as replacements

  11. Postpartum Anestrus & Rebreeding • Causes of anestrus • Uterine involution (take about 30 days) • The uterus has to go from huge to tiny again • Suckling (60 days) – BIG CAUSE • Cows – suckling keeps cow from cycling for 45 days • Heifers – suckling keeps her from cycling for 60 days • Suckling intensity decreases as calf gets older

  12. Postpartum Anestrus & Rebreeding (cont…) • Under nutrition – not receiving nutrients needed to cycle • Common belief that under nutrition prior to calving delays postpartum estrus • And under nutrition after calving reduces fertility

  13. ANY QUESTIONS???

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