All AV components that come in contact with ejaculated semen must be nonspermicidal. Reusable items must be cleansed properly to render them chemically clean, then dried, and, if possible, sterilized between uses. Soaps or disinfectants should not be used to clean AV liners because the residue can be toxic to sperm during subsequent semen collections. The rubber AV liners should be cleaned with hot running water soon after use. If smegma within an AV is allowed to dry before cleaning, the chore becomes more difficult. Cleaned rubber liners can be submerged in ethyl or isopropyl alcohol for 0.5 to 24 hours for disinfection followed by air-drying in a dust-free cabinet. Any of the latex rubber liners can be gas sterilized with ethylene oxide as long as an adequate “air-out” period is allowed (i.e., 48 to 72 hours). Sterile, nontoxic disposable equipment should be used when possible to avoid chemical contamination of ejaculates or horizontal transmission of disease. Plastic disposable AV liners, with or without attached semen receptacles, are commercially available for most AVs. This equipment helps ensure a clean, nontoxic method of semen collection. Unfortunately, some stallions do not readily accept AVs fitted with a disposable plastic liner and seem to prefer the feel of the rubber liner.

Immediately before semen collection is attempted, the water jacket of the AV is usually filled with 45°C to 50°C water to provide an internal AV temperature of 44°C to 48°C (Figure 12-6). Providing an AV temperature above that of the body seems to aid in penile stimulation and facilitates ejaculation. Occasionally, some stallions may respond more favorably to semen collection with an AV if its luminal temperature is 50°C to 55°C. Sperm can be permanently damaged, however, by contact with surfaces above 45°C. As mentioned previously, the luminal temperature of a Missouri model AV can exceed 45°C without damaging sperm, provided that the glans penis protrudes beyond the water jacket when ejaculation occurs.

The inner surface of the AV should be lubricated with a sterile, nonspermicidal lubricant before penile insertion. The collection receptacle (Figure 12-7) should be maintained at body temperature during semen collection and transport to the laboratory to prevent cold shock to the sperm before they are placed in a protective extender. Semen should also be protected from light.

To maximize the number of sperm available from each semen collection, an appropriate filter should be incorporated into the collection receptacle. The filter allows most of the gel-free fractions to pass into the seminal receptacle but traps the gel (which is presented in the final fractions of an ejaculate). Although some sperm inevitably are trapped in the gel and filter, more would be lost if the semen were filtered after collection of the combined gel and gel-free portions or if the gel were aspirated from the gel-free portion with a syringe. Nylon micromesh filters (see Figure 12-7) are superior to polyester matte filters for separating gel from gel-free fractions because they are nonabsorptive and do not trap as many sperm. The filter with its contained gel should be removed immediately on collection of the semen to prevent seepage of gel into the gel-free portion of the ejaculate.

A condom (Figure 12-8) is a poor alternative to an AV for semen collection but may be the only viable option if the stallion will not breed an AV or if an AV is unavailable. Stallions most reluctant to breed an AV are those accustomed to breeding mares by natural service and occasionally, those that have never bred before. The quality of semen collected in a condom is inferior to that obtained with an AV because of the marked contamination of the sample with bacteria and debris from the exterior of the penis.

Semen collection with an AV ordinarily is performed by allowing the stallion to mount a mare or breeding phantom. In certain situations, however, stallions have been trained to ejaculate with an AV or manual stimulation while standing on the ground (Figure 12-9). To train a stallion for ground collection, the stallion is teased to erection, and the penis is washed and dried. The stallion is approached by the collector from the left shoulder, and the AV is placed on the stallion’s penis. The AV is pushed toward the base of the penis to encourage thrusting. Stallions usually ejaculate after 5 to 10 pelvic thrusts. If the stallion does not ejaculate after the first attempt, the procedure is repeated until successful. As an alternative to ground collection, some practitioners prefer to use thin plastic mitts or rectal sleeves instead of an AV. The mitt is loosely placed on the penile shaft with 6 to 8 inches hanging beyond the end of the glans. Excess air is expelled from the mitt, and gentle pressure is applied to the glans penis to stimulate thrusting until ejaculation occurs. Application of hot compresses (6-inch squares of folded towels dipped in 50°C to 55°C water, squeezed to remove excess water from the compress), with one hand on the glans penis and one hand on the base of the penis, is often helpful in stimulating pelvic thrusting and ejaculation. A consistent, uniform method to which the individual stallion responds should be adopted. A modification of this technique can be used for chemical ejaculation (Figure 12-10). Chemical ejaculation is the method we use most often for stallions with ejaculatory problems associated with neurologic or musculoskeletal disorders that preclude mounting.