The Agony and The Ecstasy of … Frozen Semen.

I really struggle every few years when it is time to re-stock the semen tank with frozen semen.
Owning horses is risky, breeding them even more so. But breeding them with frozen semen can be both extremely convenient AND extremely risky financially speaking in this case….

The ecstasy:

The choices

Frozen semen can truly be the candy store of the Sporthorse world.

The selection and variety are just incredible. You can breed to old favorite stallions as well as the up-and-comers. Olympic caliber stallion, or their sire. You can breed to stallion stationed in Europe or in Australia. Rare breed or rare colors not available anywhere near you.

A candy store of choices… many brokers offer access to the frozen semen of a multitude of stallions from around the world. This selection above is offered by Yancey farm.

You can even breed to dead stallions. (Ferro, Darco, Weltmeyer, Galoubet)

The convenience.

Once frozen and stored at -180 degrees Celcius (-300 degree Fahrenheit) the semen can be kept indefinitely. It can therefore arrive at your breeding center weeks or even years ahead of your mare and be thawed just in time to inseminate her at the perfect moment.

Once in your possession or that of your vet, bad weather, the competition schedule of the stallion, airline strike, border crossing delays, or even pandemics will have no impact on your plans: your mare can be bred to the stallion of your choice with no issues.

For the stallion, it also offers quite a bit of an advantage.

Since frozen semen is concentrated in order to freeze it adequately one collection can yield many breeding doses. That is less wear and tear on the stallion and it frees up its time for competition and reduces the number of trips to the vet to be collected. No longer is there a need for being at the whim of the call for a collection.

When the stallion’s semen is offered frozen with the same guarantees as fresh, this can truly be an excellent option to take.

The Agony:

There is, however,  a long list of reasons why frozen can be more problematic.

Some stallions just don’t freeze very well.

Despite playing with different kinds of extender, freezing protocol, concentration some stallions just don’t have the kind of sperm that tolerate the freezing process. Some estimate that about 30% of stallion freeze very well, 30-40% freeze adequately as long as some time is taken to find the right combination of conditions, and 20-30% don’t freeze well at all.  Some of those problems can even run in bloodlines. Notably, the Heartbreaker stallion and his sons have very poor quality frozen semen. It is a real shame because he was a producer of outstanding jumping horses in Europe where his fresh semen was available. Conversely, the stallion Sandro Hit and his sons have had outstanding frozen semen over the years.

The stallion Heartbreaker (Nimmerdor/Sylvano) was truly a heartbreaker for breeders outside of Europe- his semen never did freeze well.

Breeding with frozen can be more expensive.

The thawed frozen semen is usually not as “lively” as its fresh counterpart and requires that the insemination be done closer to ovulation. That means more ultrasounds and monitoring and that means more efforts on the part of vet and insemination technicians.

Some mares, particularly those that have problems clearing the inflammation that normally comes with breeding but that is exacerbated with frozen semen, do not conceive reliably (or at all) with frozen semen or required more management.

Shipping costs.

Shipping frozen semen is also more expensive. It needs to travel in what is called a vapor shipper and without going into details it’s a large thermos-like container that weighs about 15 lbs so while there is no rush to get the container around since most hold their temperature for a week to 10 days the shipping can be a bit expensive compared to fresh semen shipped in disposable containers.

If you are in Canada and happen to buy from a US broker ( there is very few brokers in Canada) you will need to pay for the shipment in two installements. The first shipment from the broker to a Canadian distribution ( thankfully that cost is generally spread over a few buyers) and then from that location to your vets.

No guarantees. At all.

The rest of the reasons why frozen is more troublesome than fresh are related to frozen semen being offered with absolutely no guarantees whatsoever in the warmblood world.

A dose of frozen semen, what you actually buy,  is an insemination unit of “x” number of straws. The straws contain a specified concentration and volume of semen such that when thawed and combined, the “dose” of semen constitutes one breeding insemination for a mare.

Frozen straws of semen are processed with no widely used international standards. Don’t get me wrong the standards exist: it is generally accepted that a dose of frozen semen should contain a minimum of 200 million progressively motile sperm.  But those standards are not enforced or adhere to very widely because there is NO INCENTIVEs (or deterrents) to do so since the semen is sold with no guarantee!

Frozen semen is most commonly packaged in 0.5 ml straws such as these.

This absence of any guarantee means that the quality of the semen is extremely variable. Between stallion stations, between stallions, and even between the same stallion but between different collection dates.

Young stallions are usually quite fertile, and their semen can very often be frozen with good results, but once they enter competitions, it can have an impact on the quality of the sperm. Since the semen is sold without a guarantee that it will yield a pregnancy there is no incentive for the stud owners to monitor this or to make any efforts really to collect the stallion for freezing at the best time for the best quality. For some, it is simply not a priority.

There is no way to determine just by looking at the thawed semen if the stuff is fertile or not. The only thing to go is the motility (what proportion (in %) are moving forward and actively swimming)  While motility is an indicator of relative cell health, fertility is a whole other story.

Some poorly motile sperm get mares pregnant and some others with very active swimmers can’t seem to get the job done. The only way to assess fertility is with pregnancies achieved. That number is hard to get other than anecdotally, however. The stallion stations certainly don’t keep track of those numbers, why would they? Once the semen has been sold they have no longer have any accountability.

Why no guarantees?

For many years this was because breeding with frozen semen was new and delicate and if not carried out correctly even with good sperm it could yield poor results. To protect themselves the stallion owners decided to offer their stallions without any guarantees. However, this is no longer an excuse: breeding with frozen is commonplace and there really is no longer the need to protect the stud owner any more than with fresh semen. In the QH and Standardbred world, frozen semen is backed by a form of pregnancy guarantee and not surprisingly is used quite commonly with very good results.

A further word about shipping.

Finally, shipping, via vapor shipper as seen above, is not only expensive but it is also risky. There is no insurance on the shipment of the frozen semen.

Frozen semen needs to travel in a vapor shipper such as this one in its protective casing.

If the frozen container gets damaged, shipped to the wrong destination, or allowed to thaw before reaching the buyers there is next to no recourse. (And since there is no guarantee from the stallion owner the mare owner is often left with a hefty bill and no goods.) FedEx and UPS are notoriously slow and reluctant to pay out any claims and third parties don’t generally ensure perishable goods.

Poorly handling  (at any point from the stallion station to your vet hands) can damage them and make them explode upon thawing and again: there is no recourse.


It used to be that breeding warmbloods via frozen semen was an acceptable gamble: the stud fees were not as high since they did not come with any guarantees, the frozen semen shipped was generous in its numbers and if you were careful with the insemination of your mare you could get good results.

The last few years have seen the average price of frozen increase, the dose size drop, and the quality of the semen become very inconsistent.

As a result, a recent survey done of breeders that are using frozen semen found that the success rate (pregnancy achieved) was around 65%. Achieving pregnancy is not a guarantee of a live foal, so sadly the ultimate outcome is an even lower % of success.

Perhaps not surprisingly foals by stallion only available from frozen fetch a higher price, not only because they might be from the best and most popular sires available but because it also reflects how expensive and difficult it can be to get them on the ground.


Some references:


Owner and worrier in chief at Formosus Sporthorses in Alberta she's been breeding horses for over 18 years. Warmblood, warmblood crosses, and a few saddlebreds. She loves handling mare and foals and is passionate about giving foals the best start possible.

1 Comment

  1. […] we saw in our previous blog on frozen semen (The agony and ecstasy of frozen semen.) there are definite advantages and disadvantages to using frozen semen. One of the main challenges […]


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