Objective  To examine parameter changes in semen from donors in different seasons in Guangdong province and to provide evidences for determining the best time for sperm donation.

  Methods  We analyzed 15 341 semen specimens donated by 3 582 volunteers aged 22 – 45 years to Guangdong provincial human sperm bank in 2016.

  Results  The average semen volume was 3.70 ml for all the sperm donations and the average volume were 3.79 ml, 3.65 ml, 3.67 ml, and 3.73ml for the sperm donations collected in spring, summer, autumn, and winter season, respectively, with a slightly higher volume for the semen collected in spring season. The average sperm concentration was 91.5 × 10⁶/ml for all the semen donations and the average concentration were 93.3 × 10⁶/ml, 91.5 × 10⁶/ml, 89.7 × 10⁶/ml, and 92.7 × 10⁶/ml for the semen donations collected in spring, summer, autumn, and winter season; the average sperm concentration was significantly higher for the semen donations collected in spring season compared to that in autumn season (P < 0.05). The average sperm motility was 56.7% for all the semen donations and the average motility were 58.5%, 55.1%, 57.1%, and 57.0% for the semen donations collected in spring, summer, autumn, and winter season; the sperm motility was significantly higher for the semen donations collected in spring season compared to that of those collected in other seasons (P < 0.05).

  Conclusion  Seasonal factors have influence on parameters of semen donations from volunteers. The volume, sperm concentration and motility are higher for semen donations collected in spring season and spring is the best season for collecting semen donations.