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CHAPTER 1.2
The Nishikawa model AV and the Hannover Model AV (Fig. 9c) consist of an aluminum or
plastic outer casing, respectively, with a large proximal diameter and a small distal luminal diameter,
preventing the penetration of the glans penis beyond the heated portion. Although these types are
accepted well by most stallions, they are liable to cause heat damage to the spermatozoa.
The Krakow model (or adapted Cambridge model) (Fig. 9d) is a short version of the CSU AV
which allows the penis to thrust right through the length of the AV. The Krakow model is often used
as an open ended AV to allow the stallion to ejaculate into mid-air, which makes it possible to collect
individual pulses of semen and as such, allows for collection of the sperm rich fraction without the
excessive seminal plasma or gel fraction. Since contact with the glans penis is avoided, a clean
collection is performed using this AV (Allen, 2005).
Different modifications of the described AVs are being used worldwide combining the best
features of different models and avoiding the disadvantages associated with each specific type of AV.
Immediately before semen collection, the AV is prepared by filling the water jacket with hot
water providing an internal temperature of 44-48°C. Using an AV temperature above body
temperature seems to stimulate the penis and facilitates ejaculation. Some stallions require even
higher AV temperature (up to 55°C) for semen collection. In those cases, contact of the sperm during
collection with the warm water jacket must be avoided (Brinsko et al., 2011). The inner surface of the
AV is usually lubricated with a nonspermicidal lubricant. According to some authors, the use of
petroleum-based lubricants should be avoided due to sperm toxicity (Love, 1992) while others favor
vaseline to water soluble lubricant for its osmotic inactivity (Devireddy et al., 2002). The collection
receptacle should be warmed and kept at body temperature to prevent cold shock during and
immediately after collection. Usually, an isolating bag which also protects the sperm from light is
used. An inline filter can be fitted between the collection bottle and the AV to minimize trapping of
sperm in the gel fraction due to close contact after collection. This technique is superior to filtering
the whole ejaculate after collection or to aspirating the gel with a syringe. Nylon micromesh filters
are described to be superior to polyester matt filters because they are nonabsorptive, hence fewer
sperm cells are trapped. Following collection, the filter containing the gel should be removed
instantly to avoid leaking of gel into the gel-free sperm fraction.
Most often, sperm collection is performed on a dummy mare (phantom) or mount mare.
Alternatively, stallions can be trained for a ground collection, for example stallions which are unable
to mount or to maintain the mounting position. These ground collections can be accomplished by
using an AV or a plastic bag attached to the penis. In the latter case, ejaculation can be elicited either
by placement of warm (45-50°C) towel compress on the glans and base of the penis (Love, 1992) or
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