What's in your straw? Ask for the numbers!
- Laureen (Little) & Ian van Staalduinen
- May 16
- 3 min read
It's spring, I think, finally. And that means it's time to start watching our mares closely for signs that they are in 'heat' and may be ready to breed. We've selected our stallions and completed the contracts. We just need the right day to head to the reproduction vet for insemination.
What do you consider when you select a stallion for your mare? I look at their earning history and bloodlines. I check for those hereditary diseases that can plague quarter horses. I like to see previous offspring and their show results if possible. And the stud's conformation, personality, and athleticism. A cooperative owner can be very helpful for long weekend semen delivery.
When our local vet says the time is close, I'll head to Burwash - our equine reproduction vet of choice. They'll recheck the mare and when she's ready, they will order semen on the next collection day. A day of solater, they will inseminate and we are off to the races, expecting a beautiful baby in 11 months.
But it doesn't always work out as we had expected. Timing can be off - insemination has to occur within 48 hours of ovulation, the semen has to arrive on time and the semen has to be healthy.
It always surprises me that stallion owners do not routinely provide mare owners with their semen analysis results. In dog breeding, I would not use a stud without knowing their 'numbers'. Our horse world needs to catch up and become more transparent about what we are selling.
Semen evaluation should include a few measurements to provide you with an idea of the likely success of creating an embryo with your mare. Stallions do not always provide a semen sample - about 70 to 75% of the time, no semen is produced. Training of the stallion and the presence of a 'tease' mare, in heat, improves success.
Key Components of a Semen Analysis Report
Volume: The total amount of semen produced, (# mL).
The collection typically includes three fractions, with the sperm in the smallest of these.
Sperm Count (Concentration): The number of sperm per milliliter, (100-500 Million sperm / mL is typical).
Number of Sperm: usually expressed in millions (MM)
Volume of Sample | 2.5 mL |
Concentration | 200 MM / mL |
Number of Sperm | 500 MM |
Once collected, semen is fragile. It is susceptible to damage and loss of good quality sperm with exposure to light, agitation and temperature. Addition of a semen extender protects from environmental damage and improves survival of the sperm. The sample, with extender, is typically transported to the mare in a long narrow cannula or straw, packed carefully inside a thermally insulated box, with an ice pack.
Extender Selection: The sperm collected is mixed with a nutritve solution to both feed and preserve the sperm's quality until it is delivered to the mare. A few extenders are tested to see which one provides the best results for the specific stallion.
The stallion you select should provide enough semen on a single collection for two straws for later insemination. A single straw usually contains 500 Million sperm in extender (a nutritional preserving solution).
Progressive Motility:
The percentage of the moving sperm that are tracking forward, not spiralling in a circle or lying completely still. (60% progressive motility is normal)
Our 500 MM sperm are now down to 300 MM.
Morphology: The percentage of sperm with a normal shape and size. 50% normal morphology is average. Sperm can be abnormally formed in several ways; abnormal head shape, detached head, thickened tail, premature sperm.
Our 300 MM motile sperm are now down to 150 MM with good shape.
After evaluating for motility and morphology, our initial 500 MM sperm are reduced to 150 MM. Then we start the clock. Semen is generally evaluated for survival at 12, 24 and 48 hours.
Longevity: The solution is chilled and then rechecked at 12, 24 and 48 hours to give an idea of how quickly the insemination must occur for good results. Survival rates can quickly drop over time. I generally consider anything below 25% to be non-productive. If it's what you have and the mare is ready, you may give it a try anyway.
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