Examination of the Stallion for Breeding Soundness - What a Five Stage Vetting Doesn't Tell You

Semen collection techniques
Semen samples can be obtained from intact stallions by manual stimulation, chemical ejaculation, condom or artificial vagina. For decades stallion semen has been collected using artificial vaginas (AVs) for the purpose of evaluating semen production and quality and for procurement of sperm for artificial insemination or preservation. A variety of models of AVs have been developed and many will work well to reliably obtain semen samples provided they meet certain basic requirements. These requirements include; the ability to provide sufficient stimulation to the stallion’s penis through pressure and elevated temperature (typically 45–50°C), the ability to adjust size and temperature for requirements of individual stallions, a nonspermicidal receptacle to recover the ejaculated semen and protect sperm from changes in temperature and the ability to be positioned or held in place alongside an oestrous jump mare or phantom. The inner liners used for the AV must be lubricated, nonspermicidal and soft enough to promote ejaculation. The AVs most commonly used in the United States are the Colorado model and the Missouri model. In both of these models, elevated internal pressure and temperature is achieved by filling the space between 2 rubber or latex liners with warm water. Many AVs have liners or collection receptacles that include an in-line filter to prevent the mixing of sperm rich fractions of the ejaculate with the gel-fraction (contributed by the seminal vesicles) and any debris that may be introduced during collection. Nylon mesh filters are preferred over cotton or polyester ‘milk-line’ filters as they do not absorb significant numbers of spermatozoa when the semen is filtered as is the case with the milk-line filters. [...]