Lecture 12b - Manipulating Ovulation and Estrous Synchronization
Reading
Lecture 12b:
Why cycle control?
- group females for parturition
- reduce or eliminate estrus detection
- needed for AI
Manipulating ovulation
- hormonal induction of ovulation
- superovulation
Cattle
Principle of PGF Use
- regress CL
- days 5 - 17
- not effective, days 1-4 and days 18-21, represents 1/3 of estrous cycle
Induction of ovulation with PGF
- when given and CL is present, the current or next folliclular wave will ovulate
- ovulation time dependent on status of the follicular wave
Principle of GnRH use
- luteinize or ovulate a dominant follicle
- terminates follicular wave
- no effect on old CL
- dominant follicle must be present
- follow with PGF to regress CL formed or old CL
- induce ovulation of a dominant follicle
- timed AI
- no CL present
- dominant follicle must be present
Ovsynch
Ovsych Problems
- Works best on animals near day 7 of the cycle at time of 1st GnRH
- Solutions are based on Presynch protocols
- PG, 14 days, PG, 10 days, Ovsynch
- G, 7 days, PG, 3 days, G, 7 days, Ovsynch (double Ovsynch)
- G, 7 days, PG, 11 days, Ovsynch
- G, 7 days, Ovsynch (GGPG)
- PG, 3 days, G, 7 days, Ovsynch (PG-3-G)
Progestogens
- principle
- provides progesterone
- simulate a CL
- prevent ovulation
- no effect on animal's Cl - DOES NOT REGRESS CL!!!
- remove when animal's CL regresses
- current or next follicular wave ovulates
- occurs 2 - 5 days latter
- PGF used to regress animal's own CL
- administration - injection, MGA, implant, CIDR
Co-Synch + CIDR
Superovulation
- recruits and selects more follicles
- eCG or FSH
- day 17
- day 10 -12 with PGF given 2 days latter
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Sheep
- progestin as CIDR
- PGF
- lights
- melatonin
Swine
- PGF
- progestin as Altrenogest (Matrix)
- wean piglets
- puberty induction - PG600
Equine
- PGF
- HCG - >35 mm follicle
- progestins as Altrenogest (regumate)
- lights - 16 hrs/day for 60 - 90 days