Frozen Semen and Friesians

I get really frustrated when I hear a lot of people say Friesians are not good with Frozen semen. So many people and steps are involved in getting a pregnancy from frozen semen. The stallion semen quality at ejaculation, the handler's ability to follow the freezing process properly, the right extender at collection and for freezing, the right concentration in the straw, the temperature used to thaw and time in the water bath, the proper instruments (no rubber), maintaining the freezing temperatures, post thaw protocol being followed, the timing of the mare's ovulation, the mare's reproductive health, mare's physical health, mare's follicle viability, mare uterine reaction vs deep horn for insemination, the mare clearing her uterus prior to the cervix closing, a good cervix, and ultimately the embryo retention.... and a few more things inbetween...... so is it the mare...the stallion... vet.... yes and no.... a lot can go wrong at any of the steps for the process to fail

The Stallion side

It's true not all stallion's semen recovers from the freezing process the same and some don't recover at all, but that is a man/semen thing not a breed thing. Currently Post Thaw Motility is the industry indicator for evaluating semen. Obviously if you can get ahold of fertility rate with frozen semen that is most ideal. But when dealing with frozen fertility there is also a lot of error on the side of the insemination.

So lets start with what is normal. Right now 30% + post thaw motility or better is considered acceptable. You can get conceptions with lower motility but this is the industry lower number for now. Each dose should have a minimum of  250 million sperm. The stallion collection site, on the day they do the freezing, will determine the number of straws for the dose. The person packaging the semen in the 1/2 cc straws will know how many million sperm are in each 1/2 cc
So if you need 250 million progressively motile sperm for a dose and the post thaw motility is only 30% you will need to start with 833 million sperm. If each 1/2 cc straw has 200 million sperm then you would need 8.3 straws (8 or 9) if the post thaw motility is 50% then you would need 500 million sperm to start or 5 straws for that dose.
The stallion side will also know what extender is used and would have tested a few to see which is best for that stallion and which freezing method is best for that stallion. And remember motility does not = fertility, it's just the current best indicator because if it can't swim it can't get there.

Mare side

You will get the semen frozen. It should be in liquid nitrogen from the time it is frozen till right before it's put into the mare. If the semen thawed out at any time during travel the semen will not survive and will likely infect your mare with a bacteria or fungus.

your mare may or may not respond properly to hormones so the ultimate best way to handle a frozen insemination is to ultrasound the mare every 4-6 hours to make sure you are getting the ovulation and insemination timed close together. Ideally just before ovulation is best, but post ovulation is ok.

when the vet is ready to do the insemination they need to follow the instructions provided by the stallion side. If there are no instructions the industry standard is 8 straws in uterine body, 37'c water bath for 30 seconds, use a NON-rubber syringe and inseminate just the contents of the straws after it's thawed. Testing for post thaw motility at 10 minutes post thaw.  The only time the vet should stray from these instructions is if the stallion side sent different instructions. For example Botucrio is optimal at 46'c for 20 seconds. Some stallions need 15 min post thaw to be evaluated because they are slow to wake. There is only one acceptable deviation to the norm and that is doing 1/2 dose insemination pre ovulation and 1/2 post ovulation. This is used incase the mare holds her follicle (I have seen some 55mm's held for 5 days before ovulating)
               
common mistakes -
             1. adding extender to the thawed semen. Do not do this unless instructed to by the stallion sender and only using their instructions. Different semen handles different antibiotics and proteins differently and mixing extenders or using the wrong one can cost the pregnancy. if antibiotics are needed for the mare's protection the vet should administer them 4 hours post insemination in the uterine body. If the vet is worried that high sperm concentration will irritate the mare's uterus or she has a history reactions to frozen semen then use deep horn.
              2. incorrectly doing a deep horn insemination a. not getting to the deepest part of the horn so essentially doing a deep body insemination. b. putting too much volume in a deep horn insemination - 1-3 straws deep horn is sufficient there is limited space. There are single straw insemination pipettes that can be used.
              3. using too many hormones with a Friesian to get them to work on the vets schedule. Friesian mares commonly have lower fertility on the cycle after leutalize is used. Friesians tend to have larger follicles so ovulation timing drugs (even combos) that say to use at 35mm+ actually for a Friesian would be 50mm+ follicle. BUT not all Friesians get oversized follicles so it can work from time to time, or have no effect on timing the ovulation, or worse, delay ovulation
              4 not confirming ovulation. as mentioned above if the vet gives a 24 or 36hr shot to a mare that tends to have a larger follicle it could actually ovulate 5 days after they see it as a 35mm. Some Friesian mares are not even in heat with a 35mm and we have seen follicles over 65mm.

There are many more points and tips to breeding Friesians but