Stallion Semen Freezing

Firstly, why would I want to freeze my stallion’s semen?

In a nutshell, there are basically 3 types of horse breeders.

There are those who choose to own mares only, and will get their mares bred every year to either local, national, or international stallions.

Then there are breeders who usually own mares only, but will get a great stud colt, manage him until he is sexually mature, and then collect and freeze a certain amount of his semen before gelding him. That way there is semen from that stallion available for future use in the breeding program.

Lastly, there are those that keep and market their stallion to promote his genetics and offspring. These stallion owners will sometimes “stand” their stallion at a breeding station so that he is ready for collection and shipping, and/or they will have frozen semen for sale that is ready to go any time of the year. If you are considering marketing your stallion, check out this article by Todd Martin, a trainer in Texas:

Something I would like to add to that article is the decision on what type of breeding you want to make your stallion available for. The 4 types are pasture, live cover, cooled/shipped, and frozen. Some stallion owners will offer all 4 types of breeding, but remember that stallions do reach a maximum daily sperm output, and stallion over-use leads to a sharp decline in fertility.

The advantages of freezing semen is that it prevents stallion overuse as semen can be collected after the breeding season is over, for use the following season and beyond. Stallions can then maintain an active showing schedule during the breeding season instead of being busy with collections. Once semen is frozen, the quality does not decline with time (as long as it is handled properly) and so frozen semen can be marketed long after the stallion is fertile, or even after he has passed away.

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Who are the best candidates for freezing semen?

We can start freezing a stallion’s semen as soon as he is sexually mature. For most horses this is any time after 4 years old, but some horses mature earlier or later than others. If your horse is not mature at the time of collection we will be able to see signs of immaturity when examining the sample under the microscope.

It is important to know that every stallion freezes differently, and freezes better in different agents. There are a variety to choose from, and so before performing a commercial freeze, a collection will be “test frozen” with a variety of different agents in order to determine the best agent for your stallion.

What can influence a stallion’s semen quality?

Semen quality will usually start to decline as the stallion reaches 15+ years. This, again, has quite a lot of individual variability, and some stallions are quite fertile even into their 20’s.

There is a seasonal influence on stallion fertility, which makes complete sense when you look at the mare. Fertility is at an optimum level during the breeding season, and declines in late fall to the lowest level in January-February. At no point in the year would a normal stallion be considered “infertile”, his daily numbers simply drop off a bit, along with a decline in normal sperm shapes. It is not unheard of to be collecting a stallion even into December.

Disease can also influence a stallion’s fertility. Diseases that directly affect the reproductive organs are the most serious, but other diseases that change the body temperature, or require treatment with steroids or antibiotics, can also impact semen quality. Think of things like frostbite, hypothermia, serious infections, heat stress, or even colic.

What is involved in the semen freezing process?

Firstly, the stallion is dropped off at the clinic and stays for the entirety of the freezing process. This process can be as short as a week or as long as a few months, completely depending on the number of doses the stallion owner wants.

The freezing process usually starts with a “clean-out” collection if it has been more than a month since the stallion has been collected. In the next 1-2 days the stallion is then collected and a test freeze and thaw is then conducted in order to determine the best method to optimize the quality of that particular stallion’s semen. In order to maximize the sperm output for freezing, the stallion is then collected every other day (Usually Mon-Wed-Fri schedule) for the remainder of his stay. Each collection is subject to a full evaluation and post-thaw examination to determine the quality of the freeze and help with calculating the optimum number of straws per dose.

How many doses should I freeze?

What a good question! This is completely dependent on many factors, including how many mares you would like to breed, how many doses you are getting per collection, and the price at which you will be marketing the semen. Many avid breeders will look at this from a business standpoint. I will usually recommend that owners have 3 doses prepared for every pregnancy – this allows for unforeseen circumstances such as sub-fertile mares or missed cycles. Frozen semen has a slightly lower fertility rate than cooled or fresh. On average, it is about 50%, but can reach 60-75% with a fertile mare in a well-managed breeding program.

The number of doses of frozen semen we obtain per collection is also another variable. An average fertility stallion in the fall will likely have 4-5 breeding doses per collection, but it can range from 2-8 and beyond.

How can Burwash Equine Services help my breeding operation?

We offer a complete range of services that can help you through the entire freezing process. We can train your stallion to the phantom, handle him for all collections, run a complete evaluation of all collections, and perform all semen freezing, post-thaw evaluations, and processing services (including cooled/shipped processing and shipping). We are always available for help and advice regarding fertility issues and also offer complete breeding soundness evaluations.

Also remember that we provide all your mare services as well, from breeding soundness evaluations to embryo transfer, including artificial insemination with fresh, cooled, or frozen semen.

I hope you enjoyed learning about this process! If you have further questions about this process or about any of our services, please feel free to call us at (403) 242-1913, or drop us an email at