Summary. A study was conducted to determine an optimum technique for semen cryopreservation and the biological competence of frozen\p=n-\thawedferret spermatozoa. Fifty-two fresh electroejaculates from 4 males were evaluated for sperm percentage motility, forward progressive motility, motility index (SMI) and acrosomal integrity. To determine the optimum temperature for maintaining sperm motility in vitro and the influence of glycerol on sperm motility, seminal aliquants were diluted in TEST diluent (containing either 0 or 4% glycerol) and maintained at 25\s=deg\or 37\s=deg\C.For cryopreservation, semen was diluted in each of 3 cryodiluents (TEST, PDV, BF5F), cooled for 30 min at 5\s=deg\Cand pelleted on solid CO2 or frozen in 0\m=.\25ml straws (20\s=deg\C/min to \m=-\100\s=deg\C).Following thawing, SMI and acrosomal integrity were determined. Ten females with maximum vulval swelling were given 90 i.u. human chorionic gonadotrophin and laparoscopically inseminated in utero with spermatozoa previously frozen using the optimum diluent and freeze\p=n-\thawmethod. The maintenance temperature of 25\s=deg\Cwas superior (P < 0\m=.\05) to 37\s=deg\Cfor sustaining sperm motility, and glycerol did not influence (P > 0\m=.\05)motility for up to 11 h of culture. After thawing, motile spermatozoa were recovered in all treatment groups, but sperm motility and normal acrosomal ratings were highest using the PDV diluent, the pelleting method and thawing at 37\s=deg\C (P < 0\m=.\05). Seven of the 10 ferrets (70%) inseminated with spermatozoa frozen by this approach became pregnant and produced 31 kits (mean litter size 4\m=.\4;range 1\p=n-\9kits). These results illustrate the sensitivity of ferret sperm motility and acrosomal integrity to different cryopreservation conditions; and demonstrate the biological competence of frozen\p=n-\thawedferret spermatozoa.

Summary. Five domestic ferrets previously maintained for 12 weeks under a 16L:8D photoperiod were electroejaculated weekly for 15\p=n-\65weeks while continuing to be exposed to the prolonged light cycle. Two ferrets sustained spermatogenesis for 20 and 26 weeks, while sperm production in the remaining males either was sporadic or decreased, remained depressed and then increased to peak levels observed in other males. Regardless of the temporal spermatogenesis patterns within males, the number of electroejaculated spermatozoa with residual cytoplasmic droplets or abnormal acrosomes increased in all ferrets over time. Diluted ejaculates meeting artificial insemination criteria were deposited intravaginally or by transabdominal laparoscopy into the uterine horns of females treated 0 or 24 h earlier with 90 i.u. hCG. Vaginal insemination was ineffective (0 pregnancies in 10 attempts), but 17/24 ferrets (70\m=.\8%) inseminated laparoscopically became pregnant and delivered live young (mean litter size, 5\m=.\2kits). Number of motile spermatozoa deposited in utero (1\ m=. \ 6\ p=n-\ 10\ m=. \ 0 \m=x\ 106 cells), presence of glycerol in the sperm dilution medium (0 versus 4%) and time of hCG administration (0 versus 24 h before insemination) had no effect on pregnancy results or litter size.

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