Objective To examine seasonal variation in progressive motility recovery rate of frozen spermatozoa of semen samples from donors registered in Guangdong province and to provide evidences for determining the best season for semen cryopreservation.
Methods We extracted the data on semen parameters and progressive motility recovery rate of frozen spermatozoa before and after freezing for 10 919 semen samples collected from donors registered in Guangdong Province Sperm Bank between January 2016 and December 2018 and analyzed the data retrospectively.
Results There were seasonal disparities in the rate of progressive motility recovery of sperm for the semen samples. The progressive motility recovery rates (72.16 ± 14.24% and 72.43 ± 13.76%) were significantly higher for semen samples collected in autumn and winter than those (70.46 ± 14.03% and 70.72 ± 14.55%) for the samples collected in spring and summer (all P < 0.05), but there was no significant difference in the rate of the semen samples collected in spring and summer (P > 0.05); in addition, the percentages (54.95 ± 8.38% and 38.76 ± 9.41%) of sperms with progressive motility before and after freezing and the number (25.18 ± 11.74/mL) of sperms with progressive motility after cryopreservation for semen samples collected in summer were significantly lower than those for semen samples collected in winter and spring (all P < 0.05).
Conclusion Seasonal factors have effects on the progressive motility recovery rate of frozen spermatozoa and the number of sperms with progressive motility after cryopreservation for semen samples from donors in Guangdong province. The results suggest that semen sampling for sperm cryopreservation should be conducted in winter and spring season.
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