Hi, I just found this site. I had an 11 yr. old maiden mare bred, using AI on-site. I'm wondering about the timing of the use of Prostin and HCG. The mare is going to the vet for an ultrasound later today. I'm also curious about her showing heat so soon, if indeed she didn't stick. Any comments are appreciated. Thanks! Here is the chronology.
Saturday 4/30 – showing 30.5mm follicle at vet's. Taken directly to breeders
Sunday 5/1 – No large follicles showing, just a couple of small ones
Monday 5/2 – Prostin given SHOULD THIS HAVE BEEEN GIVEN SO SOON?
Wednesday 5/4 – Follicle check at 36mm, bred every other day, total of 3 times
Monday 5/23 – OPEN
Wednesday 5/25 – teasing/showing heat
Thursday 5/26 – given HCG SHOULD THIS HAVE BEEN GIVEN SO SOON?
Prostin can accelerate follicle growth on a 30 or better.
5/4 with a 36 she should be bred and given hCG. (HCG when the follicle is 35 or better)That would stimulate ovulation within 24 hours of the first cover.(sperm should be viable for 48-72 hours, she was covered 3 times)
5/25 showing heat- ultra sound her to determine what follicle size is. If follicle is at 30-32 she may be at 35 within 24 hours with a breedable follicle.
5/26 If follicle is now at 35 and she is covered, hCG should be given. Was she covered? hCG will not work if the follicle was not at 35. It would be too soon if she was at a 35, given the hCG and no semen was present when the ovulation occured.
Remember, if you are not following the follicle, then you must assume that she will ovulate within the 24-48 hours of her last cover. That is why the hCG must be given within 24 hrs of the final cover. There is a small window (6hrs)for insemination after ovulation has occured.
If you do follow the follicle, then you know that on a 35 you have a breedable follicle that will respond to the hCG.
Are you sure that she is showing a true heat, or could she be reacting in a submissive behavior to the teasing stallion?
Timing is everything, ultra sounds can save time and effort. I would also suggest the use of Oxytocin at the appropriate time post breeding.
Thanks for the reply. The breeder only uses ultrasound for determining the size of the follicle prior to breeding, then teasing the mare. They AI every other day for up to three times. From what you're saying, they used HcG too soon.
The vet's ultrasound showed she was not pregnant, yesterday, and she had one collapsing follicle, and two other follicles (30mm and 25mm). She was still showing standing heat to one of my geldings late yesterday afternoon, so the breeder had me bring her back last night. They'll ultrasound her today and breed if things look right. My vet thinks giving the prostin too soon the first time around might have messed her up.
Whether the Prostin (PGR2a) should have been given on 5/2 depends greatly upon whether that 30.5 follicle present on 4/30 regressed or ovulated. In order for PGF2a to work, there must be a functional Corpus luteum (CL) present, and that would not be so until about 6 days after an ovulation occurred, and then through until the natural release of PGF2a destroys it about 7 days later. There is more information about why PGF2a doesn't work in the articles section of this site (follow that link).
As TX Breeder notes, the follicle must be at 35 mm for a reliable response (ovulation stimulation) to hCG to occur. It is surprising if this farm is using ultrasound that they would not be confirming follicular diameter prior to giving the hCG.
Overall, I think a closer evaluation process needs to be carried out with the mare. There is evaluation happening, but from what you say it is a little "hit and miss".
Hi all, It is the beginning of the breeding season here in Australia starting next month, and I have had my mare under lights for the past 4weeks. She has just come into season, and is presenting herself to the stallion. I know these transition heats arent normally fertile, and i was wondering when the best time to start breeding her with my stallion would be? It is the stallions first year to breed a mare, and i put this mare under lights to increase the length of the season a little to give him the best chance to settle her. Would the second/third heat be more likely to be more fertile? Any help would be appreciated. Thanks
Hi Renee - I didn't try to breed my mare on her first cycle in March. Then, she didn't appear to cycle back until the end of April. Her next two cycles were a bit wacky and she didn't catch. Third time's a charm, though, as she was determined in foal after being bred in her later June heat. She was still carrying it at her 45 day u/s, so things are looking promising.
You can use this heat to culture her though and make sure when you breed her on her next heat she is clean.
Please note that opinions, product information, advice or suggestions posted on this bulletin board are not necessarily those of the management at Equine-Reproduction.com nor does the maintenance of the post position indicate an implicit or any endorsement of that information, opinion or product.
Further, although we have the greatest respect for the posters offering assistance here, you are advised to seek a consultation with your veterinarian prior to using information obtained from this board if it is of a veterinary nature.Proud to be sponsored and supported by: