Semen extenders for artificial insemination in the American alligator

Abstract Semen was collected post-mortem from 19 male alligators ( Alligator mississipiensis ) by dissection of the genitalia. In 12 of 13 wild alligators, two of two farmed alligators, and three of four zoo alligators adequate numbers of spermatozoa (>1 × 10 9 total cells) were collected for semen preservation and artificial insemination studies. Semen extended in solutions containing a combination of egg yolk and milk, rather than either of these constituents alone, was superior for long-term liquid storage. The addition of either penicillin with dihydrostreptomycin, or gentamycin, in combination with yolk and milk enhanced the longevity of sperm cells as compared to maintenance of motility in solutions without antibiotics. Both glycerol and DMSO were detrimental to sperm cell motility. Dimethyl sulfoxide (DMSO) was less detrimental than glycerol. Semen frozen by pelleting on dry ice resulted in loss of motility of all but 0–2% of spermatozoa in all extenders tested. Neither DMSO nor glycerol was beneficial in protecting sperm cells during freezethaw compared with extenders not containing these compounds.