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The Great Mare Synch Up. By: Bill Sattler Brandon Kurth Ariana Radke. Equine Dilemma. Breed 10 mares in 2 weeks Natural breeding only (no A.I.) 1 stallion able to do 1 mating per day. / 2weeks = A Lot of work. X 10 +. Case Specifics. Mares arrive Jan. 15
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The Great Mare Synch Up By: Bill Sattler Brandon Kurth Ariana Radke
Equine Dilemma • Breed 10 mares in 2 weeks • Natural breeding only (no A.I.) • 1 stallion able to do 1 mating per day / 2weeks = A Lot of work X 10 +
Case Specifics • Mares arrive Jan. 15 • Finish breeding w/in 1 week of Feb. 15 (Feb. 8th – 22nd) • Mares under lights since Dec. 1, should ovulate within 60 days ( by Jan. 29th)
Options for Treatment • HCG stimulates ovulation • PGF2a induces luteolysis • Progestin negative feedback prevents estrus and ovulation
Equine Family Planning Upon arrival (mid January), begin exposing mares to a stallion daily to hasten the start of cyclicity On Feb 26, palpate or ultrasound all mares to determine if the mare has begun to cycle as determined by the presence of a CL or large follicles Mares which are cycling are assigned to start oral progestin treatment (Regumate), start one mare on Jan 26, another mare on Jan 27 and so on until all mares have been started on regumate. Start only 1 mare/day. Administer progestin for 9 days. After all cycling mares are started on progestin, check mares originally determined to be non-cycling and if now cycling, start them on progestin following a similar design.
Equine Family Planning cont. On the last day of progestin treatment, give PGF2alpha to regress any CL that may be present Detect estrus of mares with a stallion after stopping progestin treatment. Mares will likely come into estrus 2 - 3 days after stopping progestin treatment. Breed on the 3rd day of estrus and give HCG following breeding to ensure ovulation occurs. An alternative is to give HCG on day 3 of estrus, breed on day 4 Check mares 48 hr after breeding to ensure ovulation has occurred. Rebreed if ovulation has yet to occur.
Drug Use • Progestin - binds to steroid hormone receptor in nucleus of hypothalamic cell, negative feedback to prevent further ovulation, also sensitizes hypothalamus such that upon removal hypothalamus can have positive feedback to estrogen from follicles. • PGF2a-targets cells of corpus luteum to cause luteolysis, response by Ca2+ 2nd messenger w/ neg. feedback • HCG- targets follicular cells, response by cAMP 2nd messenger, triggers ovulation of large preovulatory follicles
Game Plan • Treatment regime • Determine if mares are cycling • Give progestin (regumate) orally for 7 days, • PGF2a given on day 7 to ensure no CL remains • Tease/detect estrus (estrus starts 2 days after progestin is stopped) • Breed day 3 of estrus • HCG given same day as breeding • Alternative is to give HCG on day 3 of estrus • Breed on day 4 of estrus • Confirm ovulation on day 5 of estrus Stagger pattern start, 1 day apart for each of 10 mares.
Requirements for Plan to Work • Non pregnant • Mare must be detected as cycling prior to progestin administration • Needs to under go light treatment on Dec. 1 • Recognise that only 60 - 70% of mares will become pregnant under best of circumstances from a single breeding
How Do You Know It Worked? • Post breeding teasing (estrus continues for 1 -2 days after ovulation) • Rectal palpation (detect ovulation) • Ultrasound (detect ovulation)
Labor Needs • Veterinarian to palpate or ultrasound mares before giving progestin and after breeding to check for ovulation • People for teasing • At least one other stallion for teasing • Extra staff for extra mares • Good record keeping