Estrous synchronization

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Estrous synchronization ovulation induction

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References

• Hafez, E.S.E. and Hafez, B. Reproduction in farm
  animals
• seven edition
• Gasser, C.L. and Day, M. L. Current and Future
  Estrous Synchronization Systems.
• WAAESD Handbook of estrous synchronization

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Estrous synchronization

• Estrous cycle 21 days (17-24 days)
• Synchronize or induce
• Normal estrous cycle

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Synchronization in Farm animals

• Days to first breeding (DFB)
• voluntary waiting period (VWP)
• TAI or Fixed Time AI

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Synchronization

• Shortening the luteal phase
• Luteolysis
• PGF2?
• Estrogen
• Extending the luteal phase
• Long term of progestogen 14-21 days
• Negative feedback on LH

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Advantages of synchronized ovulation

• Can synchronize large group to ovulate
• at same time
• Shorten calving season
• Reduce labor required for AI breeding
• Reduces overall management problems
• with AI
• Market uniform calf crop (same age)
• Improves management practices (cattle
  grouped-closer observation, better feeding
  practices, etc.)

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Disadvantages of synchronized ovulation

• Low conception rates
• Cost
• Concentrated labor required during
• breeding and calving season
• Cows all calving at once (especially
• bad if have many calving problems)

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Compounds used in ovulation synchronization

• Progestogens or progestagens
• 1. Progesterone
• Neutralizes the corpus luteum and its natural
  production of progesterone to rearrange cycle
• Used in cattle
• CIDR, PRID

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Progestogens

• 2. Synthetic progestogens
• - Norgestomet Crestar (implant)
• - Medroxyacetate progesterone (MAP) Inject
• - Melengestrol acetate (MGA) (oral)

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Prostaglandins

• Prostaglandins
• - Ceases function of the corpus luteum
• - Must have functional corpus luteum
• - No effect on developing CL before
• 5 days of age
• - No effect on waning CL after
• about 16 days of age

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PGF2?

• Natural PGF2?
• Dinoprost tromethamine (Lutalyse)
• Synthetic analogue
• Cloprostenol sodium Estrumate
• Luprostinal Prosolvin
• Etiproston tromethamine Prostavet

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PGF2?

• Prostaglandin analogue
• a. Very similar to prostaglandin compounds
• b. Can separate the effects of the prostaglandins
  (e.g. analogues produce less sweating in mares
  than prostaglandins)

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PGF2?

• Intramuscular injection requires higher dosage
  than intrauterine injection because of the short
  half-life of the substance
• a. Metabolizes quickly once in circulation
• b. Half-life about 2-3 minutes approximately
  90 deactivated in single passage through body
• Used in cows, ewes, sows and mares
• IVSM (intravulvosubmucosal)
• Warninggtgtgt Causes of abortion

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GnRH agonists

• Hypothalamus hormone
• Release of FSH, LH
• Buselerin (Cystorelin, Factrel, Fertagyl,
  OvaCyst)

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Estrogens

• Estradiol conjugates
• Estradiol valerate
• Estradiol bazoate
• Estradiol cypionate

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Gonadotropins

• eCG or PMSG (equine chorionic gonadotropin or
  pregnant mare serum gonadotropin)
• FSH ( follicle stimulating hormone)
• hCG (human chorionic gonadotropin)

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Swine synchronization

• 1. Progestogen (Altrenogest) (Regumate)
• Fed 14-18 days
• Normal estrus begins on 4-5 days after withdrawal
  
• Estrus 2-4 days
• Fixed-time 6-7 days after progestogen withdrawal
• Side effects in swine
• - Development of cystic follicles
• - Lowered fertility

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Swine synchronization

• 2. Inject 500-1000 IU of hCG
• On days 12
• Then Inject PGF2? about 3 weeks later

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Horses synchronization

• Altrenogest (Regumate)
• Fed 15 days
• Estrus 3 days after withdrawal
• PGF2?
• Diestrous
• Single injection ? estrous 3-5 days
• hCG and PGF2?

PGF2? hCG PGF2? hCG estrus
1 7-8 15 21-22 2-4
days
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Sheep and Goats Synchronization

• Ewes estrus (16 days) Does estrus (21 days)
• Progestogen (implant or pessary)
• Implant 12-14 days sheep
• Implant 18-21 days goats
• Inject eCG 400-800 IU at withdrawal
• TAI ewe at 48-60 hrs and does 30- 48 hrs after
  progestogen withdrawal

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Sheep and Goats Synchronization

• PGF2?
• Ewes 2 injection 9 days apart double AI at 2-3
  days
• Does 2 injection 11-12 days apart AI or natural
  mating at 2-3 days

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Cattle synchronization

• PGF2?
• Two PGF2? 11-14 days apart
• Estrus 72-96 hrs

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Cattle synchronization

• Progestogen and PGF2?
• Vaginal pessary CIDR or PRID 7 days
• PGF2? inject at 6 days
• AI at Estrus (48-72 hrs)

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Cattle synchronization

• MGA and PGF2?

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Cattle synchronization

• Progestogen and estrogen
• 3 mg Norgestomet implant
• 5 mg estradiol valerate inject
• removal implant 9 days
• AI when esturs or TAI 54 hrs after removal

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GnRH and PGF2?

• Novel protocols
• GnRH agonist
• PGF2?
• CIDR
• MGA

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Heat-Synch ECP at 48hrs
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