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Conventional method of oestrus synchronization in sheep
The document outlines various methods and principles of oestrus synchronization in sheep, emphasizing the importance of artificial manipulation for improved breeding efficiency and profitability. It discusses the merits of synchronization, including reduced labor and improved accuracy, as well as different agents and administration methods such as progesterone and prostaglandins. Additionally, the document highlights natural methods like the 'male effect' and photoperiod manipulation, along with their respective advantages and disadvantages.
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Conventional method of oestrus synchronization in sheep
- 1. Conventional method ofOestrus synchronization in sheep Zeleke Mekuriaw EIAR-DBARC-ICARDA-ILRI (LIVES)-FAO Training on Reproduction in Sheep and Goat, Debre Berhan, Ethiopia, 13-15 October 2014
- 2. Outline Introduction Merits of oestrus synchronization Principles of oestrus synchronization Methods of oestrus synchronization • Exogenous Progesterones/progestagens o Routs of administration • Prostaglandins /analogues • Natural Method 2
- 3. Introduction • Naturally,mating occurs when female is receptive regardless of herdsman’s willingness. • Artificial manipulation is important to the advantage of increasing the efficiency and profitability of the farm. • One of the artificial manipulation techniques is oestrus synchronization. 3
- 4. Introduction… Oestrussynchronization: • Artificial induction of heat in females simultaneously • Labour and time management tool • A breeding tool 4
- 5. Merits of oestrussynchronization • Reduces time and labour for heat detection • Improves accuracy of heat detection • Facilitates application of fixed time AI • Facilitates MOET 5
- 6. Merits of oestrussynchronization… • Enables programed mating • Enables programed lambing (targeting feed availability, market, health) • Induces ovarian activity in anoestrus ewes & pre-pubertal ewe lambs • Age uniformity in lambs (fore selling, feeding & healthcare) • Physiological similarity of ewes (for feeding management) 6
- 7. Methods of oestroussynchronization in ewes Various synchronization agents available The choice depends on: – effectiveness in regulating ovarian activity – Precision of the control (compactness) – Fertility from induced oestrus – Ease of administration – Absence of undesirable side effects – Cost effectiveness 7
- 8. Principles of oestrussynchronization 1. Shortening life span of CL-PGF2ɚ/ analogue 2. Prolonging luteal phase- Progesterone/progestagen 8
- 9. Comparison of prostaglandin& progesterone based synchronization Progesterone/its analogue Prostaglandin/its analogue Advantage Induces cyclicity Cheaper More compact synchrony Easy to apply Does not induce abortion Treat luteal cyst Limitations Expensive Effective only in cycling cows Complicated application procedures Effective from 4 to 14 days of estrous cycle (matured CL) Induces abortion if pregnant ewe is injected by mistake Less compact synchrony 9
- 10. Use of ExogenousProgesterone/Progestagens – Exogenous progesterone/progestagens extend luteal phase – the CL regresses naturally during the period when exogenous source is applied. – The exogenous source continues to exert a negative feedback on FSH and LH secretion, even after CL regression. – When external source is later withdrawn, follicular growth starts simultaneously in all treated females. 10
- 11. Routes of administrationof progesterone/progestagens • Oral administration • skin implants • Intravaginal treatments 11
- 12. The oral administration – Melengestrol acetate (MGA), an orally active synthetic progestagen – twice daily feeding of 0.125 mg MGA for an 8-day period could induce an out-of-season synchronized oestrus in ewes. Drawbacks: – time and labour costs involved in oral dosing – difficulty to achieve a smooth and steady input of progestagen – Less practical due to lack of sharp and predictable result
- 13. Implant treatments –Subcutaneous implant of he potent progestagen, norgestmet used. – About 1cm implant contains 1.2 or 3mg of norgestmet is inserted for 12 days. – Mean time of onset of oestrus after removal of implant is 26 to 30 hrs
- 14. Intravaginal administration The treatment of choice for oestrus synchronization in sheep (in all seasons). • Progestagen impregnated sponges used • Inserted over periods of 12 to14 days • Used in conjunction with PMSG
- 15. Intravaginal administration … • FGA (Fluorogestone acetate) – marketed as Chronogest® or Cronolone®. (45 mg), – widely used either in conjunction with PMSG, FSH or PGF2ɚ
- 16. Intravaginal administration… •MAP (medroxyprogesterone acetate ) – 6-methyl-17-acetoxyprogesterone – marketed as Veramix (Pharmacia & Upjohn, Orangeville, Canada) – Contain 60 mg of the progesterone analogue – The same effect as FGA
- 17. Intravaginal administration… •CIDR (Controlled Internal Drug Releasing) – dispenser developed in New Zealand. – constructed from a natural progesterone impregnated medical silicone elastomer.
- 18. Intravaginal administration… Meritsand demerits of CIDR device Merits – natural progesterone – aesthetically more pleasant to handle Demerits – higher incidence of loss (13.5%) compared to sponges (6.7%) – more expensive than the progestagen sponges
- 19. Use of Prostaglandins/ their analogues • The administration of PGF2ɚ causes regression of the CL • Possible only from day 4 to 14 of the cycle • No response to PGF2 administration during the refractory period (0-4th & 14th- 16th day of oestrous cycle) • The technique only suitable during the breeding season • Onset of oestrus 36-48hrs after injection
- 20. Natural Method ofsynchronization Male effect: – sudden exposure to rams – The duration of exposure (6 days for goats, 15days for sheep) – isolation period (at east 3 wks) – distance of isolation (100-500m) Photoperiod: – manipulating the light environment combination of the two -photoperiod and male effect
- 21. Natural Method ofsynchronization… Merits : – relatively cheaper – More consumer preference/“hormone-free” animal products. Demerits: – variability in the onset of oestrus – requires insemination at the observed heat
- 22. www.lives-ethiopia.org The presentationhas a Creative Commons licence. You are free to re-use or distribute this work, provided credit is given to ILRI.
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