Stallion Semen Collection

Semen collection and evaluation is an integral part of any breeding program. It allows stallion owners to assess the breeding soundness of their stallion. The fertility is evaluated by calculating the concentration, motility and morphology of the sperm within the sample. This process also allows the opportunity for stallion owners to offer fresh, chilled and frozen semen for artificial insemination. 

How is semen collected?

The most common method of collecting semen involves using an Artifical Vagina (AV). The stallion will have been trained to mount a breeding dummy/phantom or a very quiet experienced “jump” mare to allow the vet access. The dummy is set to the preferred height and angle specific to the stallion. The AV is also set up to the correct temperature, pressure and lubrication specific to each stallion. The stallion is either teased using an in-season mare or urine from an in-season mare. Once fully erect, the stallion mounts the dummy/phantom and the AV is placed over the penis for collection of the semen. The semen runs through a filter to catch the gel portion of the ejaculate and the sperm-rich part is collected into a pre-warmed bottle. The semen is then immediately taken to the laboratory equipment in order to analyse and process to prevent degradation of the sample.

Over time, stallions may not require specific teasing and just be presented to the dummy/phantom for collection.

This collection process requires at least two members of staff to ensure the stallion mounts the dummy correctly and it is safe for the vet to collect. Dummy training is essential for the stallion prior to collecting in the season. This may only take a few attempts or can take several weeks with multiple people to assist.

Alternative methods include ground collection with the AV, drug-induced ejaculation and epididymal sperm harvesting. The stallion owner will work closely with their vet to identify the best method of collection for their stallion.

What are you looking for when evaluating semen?

1. Volume of the sample - the total amount that has been collected 
2. Concentration - Equipment such as a spectrophotometer or haemocytometer enables a count of the total number of sperm in the sample. The concentration estimate is then calculated by dividing the total number of the sperm by the total volume. Approximately most stallions produce 100 to 500 x 106 spermatozoa/mL.
3. Extender - Protein based extenders are added to ensure the longevity of the sample. This is initially put in as a 1:1 ratio to prevent degradation of the sample. The specific amount required is then calculated based on the concentration of the sample.
4. Motility - There are two motility factors to quantify from each sample; total motility and progressive motility. Total motility highlights how much of the sample is moving. Whereas progressive motility highlights how many of the moving sperm are actually moving forwards and progressing (not circling). This is important to their function as the sperm need to reach the egg and penetrate its wall in order to fertilise and form an embryo. A good quality semen sample should have a progressive motility of at least 60%. 
5. Morphology - This describes the shape/structure of each sperm and looks for any abnormalities that might affect its function (e.g. bent heads, detached head/tail etc.)
6. Sperm longevity - Different extenders are used to evaluate which gives the sperm the best longevity. Each dose is extended appropriately then the samples are evaluated at 12h, 24h, 48h.

Using the information collected by a thorough evaluation, the vet can determine how many breeding doses can be made from the one collection.

It is beneficial to evaluate stallion semen at the beginning of each breeding season for the purpose of age related changes or any lifestyle changes the stallion has experienced that may affect semen quality.

What are the benefits of collecting semen for artificial insemination?

• The biggest benefit is safety for all parties involved:
  • For the stallion - reduce the risk of mares that may kick or the risks associated with live cover and animals in the “heat of the moment”
  • For the mare - from stallions that may bite or be overly rough through live cover 
  • For the handlers - decreased injury risk having to manage both mare and stallion
• Disease control is also a big factor so that semen can be tested and treated for any infectious diseases before insemination and even limits infections sexually transmitted with live cover
• Genetic diversity and access to a greater number of stallions to improve worldwide genetics (semen can be frozen to allow the use of deceased stallions and this can be stored indefinitely)
• Advanced technologies in reproduction has allowed increased conception rates- a controlled breeding program can be achieved
• Greater efficiency where one collection can be used to inseminate multiple mares