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Control pf Repro= SHEEP (Synchronization of Oestrus (General (When= at end…
Control pf Repro= SHEEP
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One preg/yr (150d), single/twin
Mx of preg, lambing, lactation so NOT interfere with wool quality
A. Ram Effect
What= Isolate ewes, introduce rams/ androgenised wethers
= Androgen-dependent pheromone induces LH surge
= Ovulation within 48hrs
= Silent oestrus (no Prog. priming)
= Second oestrus 17d later (18-20d after rams in)
May be early regression of first CL after 6d
= second silent ovulation
= third normal oestrus 17d later (25d after rams in)
B: eCG
stimulate follicular development= follicles produce oestrogen (positive feedback)= LH surge= ovulation
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- Synchronization of Oestrus
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A. Progesterone
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How= Intravaginal sponges (e.g. Repromap, Chronogest), Injections, Implants
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When give for 14d= A turned into C, B held at C, C also held at C
Stop prog= all come into oestrus in 2-3d
B. PG
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How= 2 injections, 9d apart (synchronise end of luteal phase)
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Applied
A farmer has 300 ewes and wishes to use artificial insemination with top quality frozen semen. Design a program of synchronisation for these ewes. The management of the sheep is intensive, and could successfully cope with twin lambs
- Progesterone intravaginal-14d
- Teasers and eCG in at sponge removal
- AI to detected oestrus 2-3d after sponges out
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- Increasing Ovulation Rate
- Induction of Parturition and abortion
PG= luteolytic, induce abortion/ parturition
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Control of Repro= GOATS
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Photoperiod Effect
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Artificially increase light hrs, abrupt decrease when natural winter lighting outside
Progestagen Sponges +/- eCG, PG 48hrs before sponge removal
- Synchronisation of oestrus
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- Induction of abortion, parturition
PG
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Abortion with PG= followed by short cycles, not good fertility
Control of Repro= SOWS
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Mx stimuli= mix gilts, transport
Hormonal
eCG/hCG: induce growth, then mature and ovulate follicles
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- Synchronisation of Oestrus
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PG
Day 11 onwards, farrow 24-30hrs later
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