Semen collection in horses is crucial for modern equine breeding, facilitating artificial insemination, genetic preservation, and fertility evaluations. It allows breeders to manage genetics precisely and safely, reducing natural breeding risks. Collected semen can be used fresh, cooled for transport, or frozen for long-term storage, providing flexibility in breeding programs.
Primary Collection Methods
The most common method uses an artificial vagina (AV). This device is designed to mimic the natural conditions of a mare’s reproductive tract, providing the necessary temperature, pressure, and lubrication to stimulate ejaculation. The AV typically consists of a rigid outer casing, a flexible inner liner, and a water or air-filled jacket that maintains the internal environment. A collection receptacle, often with a filter to separate the gel portion of the ejaculate, attaches to the end of the AV to capture the semen. Stallions are commonly trained to mount a “phantom” mare or a live mare in heat, with the penis then diverted into the artificial vagina.
Other methods are available for stallions that cannot or will not use an artificial vagina due to physical limitations or behavioral issues. Pharmacological induction of ejaculation involves administering specific medications to stimulate the process. This approach is particularly useful for stallions with musculoskeletal, neurological, or behavioral abnormalities preventing natural mounting or erection. Ground collection is another alternative where the stallion remains standing, and the artificial vagina is applied manually, sometimes with additional stimulation.
Preparing the Stallion and Equipment
Before semen collection, preparation of both the stallion and the equipment ensures a successful and hygienic process. The stallion needs to be properly handled and sexually aroused, often achieved by parading a “teaser” mare nearby or allowing interaction with a phantom mare. This stimulation helps the stallion achieve full erection and readiness for collection. The stallion’s penis is typically washed with clean, warm water to remove dirt and debris, preventing bacterial contamination of the semen sample.
Preparing the artificial vagina involves temperature and lubrication adjustments. The water jacket of the AV is filled with hot water to achieve an internal temperature of 42 to 48°C, mimicking a mare’s body temperature for optimal stimulation. A sterile, non-spermicidal, water-soluble lubricant is applied to the inner liner for smooth penetration and to protect sperm. All equipment that will contact the semen, including the collection bottle, is warmed to approximately 38°C to prevent cold shock to the spermatozoa.
Post-Collection Handling and Assessment
After collection, the semen sample requires careful handling to preserve viability and integrity. The collected ejaculate is typically filtered to remove the gel fraction, which contains no sperm. The sample must be protected from environmental factors that can damage sperm, such as extreme temperatures, direct sunlight, and agitation. Prompt transport of the sample to a processing area is important for immediate evaluation and further processing.
Initial assessment of the semen involves a gross evaluation, noting the total volume, color, and consistency (opacity) of the ejaculate. Following this, a more detailed laboratory evaluation is performed to determine the quality of the semen. Key parameters assessed include sperm motility, which measures the percentage of actively moving sperm, particularly those with progressive, forward movement. Sperm concentration, or the number of sperm per unit volume, is also determined, along with morphology, which identifies the percentage of normally shaped sperm and any abnormalities. Semen extenders are often added to dilute the sample, providing nutrients and protecting the sperm during storage and transport.