Artificial Vagina for Rabbits
To the Editor:
We read with interest “Development of an Inexpensive Artificial Vagina for Semen Collection From Rabbits” by Naughton et al (J Androl. 2003;24:712–715) and consider the underlying premise flawed. The abstract incorrectly states that “no easily reproducible or inexpensive device for semen collection (from rabbits) has been reported.”
Prior to the mid 1960s, a “Walton-type” artificial vagina (AV) was used to collect rabbit semen. Amann and Lambiase (1967) and others provided a citation path leading to Macirone and Walton (1938). Each user had his or her own homemade version of this AV. For many years, IMV Technologies (www.imv-technologies.com) has sold a Walton-type AV; currently it costs $42.
The rabbit AV illustrated with instructions for fabrication by Bredderman et al (1964) rapidly gained wide acceptance because of convenient usage, minimal sperm loss, and low cost. It remains in use. A technician could fabricate a Bredderman-style AV from materials costing <$3.00 (including latex liner) plus $2.50 or $9.00 for a cutoff, 15-mL graduated centrifuge tube (polycarbonate or glass). This AV is easily washed and sanitized, so cost per ejaculate is very low.
Consistent quantitative recovery of ejaculated sperm is essential for most studies, yet Naughton et al did not estimate sperm loss in their AV. They implied that sperm loss in the collection condom might be substantial. Sperm loss within a Walton-type AV averaged 10% of the total number ejaculated (Amann and Lambiase, 1967), and loss averaged <4% within a ≤6-cm long Bredderman-style AV (Bredderman et al, 1964).
Considering semen collection, we never sedated a “teaser doe”; <1 in 10 are/become obstinate and should not be used. A selection of female and male teasers is essential. The teaser should be placed into the male's cage rather than vice versa. Sexual preparation (ie, 3 false mounts; Macmillan and Hafs, 1967) is essential to maximize “harvest” of available sperm. False mounts are accomplished by “brushing” the male off the teaser several times before allowing ejaculation into the AV. Lack of sexual preparation likely contributed to low values for total sperm per ejaculate noted by Naughton et al. In our experiences (hundreds of males), urination concomitant with ejaculation is rare and usually results from too warm an AV. Even with proper temperature (43°C to 49°C), an occasional male urinates frequently; if feasible, he might be excluded from a study. Proper evaluation of a male requires multiple collections every 2 or 3 days, using false mounts, over a period of weeks or months (Amann and Lambiase, 1967; Foote et al, 1986).