Semen collection from stallions is a fundamental procedure in modern equine breeding, serving the twin purposes of artificial insemination (AI) programs and comprehensive breeding soundness examinations. This practice allows for the safe, controlled assessment of a stallion’s reproductive potential and facilitates the breeding of numerous mares from a single ejaculate, often across great distances. Successful collection relies on specialized equipment and a controlled environment to safely obtain a high-quality sample that accurately reflects the stallion’s fertility. The technique must be precise because equine sperm is highly susceptible to damage from light, agitation, and sudden temperature changes, making meticulous handling paramount.
Preparing the Stallion and Equipment
Before the actual collection can begin, a strict protocol of hygiene and equipment preparation must be followed to ensure the safety of the stallion and the viability of the sperm. The collection area, often a dedicated breeding shed, must be safe, clean, and large enough to prevent injury to the horse and handlers. The primary piece of equipment, the artificial vagina (AV), must be prepared to mimic the natural conditions of the mare’s reproductive tract.
The AV consists of a rigid outer casing and a flexible inner liner filled with water to create the necessary temperature and pressure stimulation. Water is typically heated to about 50 to 55 degrees Celsius before being added to the AV jacket, achieving a final internal temperature of 42 to 48 degrees Celsius at the time of collection. This temperature range provides the necessary thermal stimulation for ejaculation, but temperatures above 45 degrees Celsius risk damaging the sperm cells.
A sterile, non-spermicidal, water-soluble lubricant is applied to the inner liner, covering about two-thirds of its length to ensure smooth penetration without contaminating the collected sample. The pressure inside the AV is then adjusted by releasing or adding small amounts of water or air, tailoring the tension to the stallion’s individual preference for optimal stimulation. Preparing the stallion involves stimulating an erection, often with the sight and scent of a mare in heat. The penis is then washed with clean, warm water using a gloved hand to remove dirt, debris, and smegma, ensuring that no soap or disinfectant is used, as their residue can be toxic to sperm.
The Procedure Using an Artificial Vagina
The physical collection process typically involves the stallion mounting either a breeding phantom, which is a padded, stationary dummy, or a quiet, non-kicking mare, often referred to as a jump mare. Using a phantom is often preferred in commercial settings as it is safer for personnel and can be adjusted for the stallion’s comfort, while a teaser mare is used to encourage the initial sexual arousal. Once the stallion achieves a full erection and mounts, the handler guides the penis away from the phantom or mare and directs it into the prepared artificial vagina.
The collector must brace the AV firmly against the side of the mount, ensuring the device is held at an angle that simulates the natural position within a mare. The AV’s temperature and pressure provide the tactile stimulation needed to initiate the powerful pelvic thrusts that precede ejaculation. During the collection, the collector will feel a series of distinct pulses at the base of the stallion’s penis, indicating the rhythmic contractions of the urethra.
A clear visual sign of successful ejaculation is the phenomenon known as “tail flagging,” where the stallion’s tail moves up and down rapidly with each pulse of semen. Ejaculation typically occurs in a series of five to seven jets, which contain varying concentrations of sperm. As the stallion completes the process, his penis softens, and he naturally begins to back off the mount. At this point, the collector carefully lowers the end of the AV to allow the collected semen to flow by gravity into the attached collection receptacle, which is often a sterile, pre-warmed bottle or bag.
Initial Handling and Evaluation of the Sample
Immediately following collection, the sample must be protected from environmental factors, as equine sperm is extremely sensitive to light, rapid temperature change, and agitation. The collection receptacle is quickly transported to a processing area, where initial handling and evaluation begin. The first step involves filtering the sample to remove the gelatinous portion of the ejaculate, known as the gel fraction, which is composed of secretions from the seminal vesicles.
The gel-free semen is then placed in a pre-warmed incubator or water bath to maintain a temperature between 32 and 38 degrees Celsius, preventing cold shock. This initial assessment involves measuring the sample’s total volume and evaluating several parameters to determine its viability for breeding. Concentration, the total number of sperm per milliliter, is measured using a specialized instrument like a spectrophotometer.
Motility is assessed microscopically, looking for the percentage of sperm that are moving (total motility) and those moving forward in a straight line (progressive motility). A goal of at least 50% progressive motility is desired. The Morphology, the physical structure of the sperm, is also examined to ensure at least 50% of the cells are structurally normal. To preserve the sperm cells and provide them with energy for storage and transport, the sample is quickly diluted with a specialized solution called an extender. This immediate assessment and dilution determine whether the semen is suitable for fresh use, cooling, or cryopreservation.