Semen quality in a Giant Panda (Ailuropoda melanoleuca) in relation to estrus of a nearby resident female panda

Semen quality was determined in a sexually mature male Giant Panda, electroejaculated 13 times during a 5-year interval, before, during and after estrus of a female Giant Panda housed nearby. Testis volume and plasma testosterone concentrations were also measured. Mean testis volumes were 1223.0 ± 64.7(S.E.M.) cm3 (before estrus), 1213.2 ± 218.2 cm3 (during estrus), and 1360.2 ± 160.4 cm3 (after estrus). Compared to before and during estrus in the female, testis volume decreased 70 days after estrus and there was no projectile ejaculation. The mean semen volume and sperm count were 2.2 ± 0.7 mL and 8.3 ± 3.1 × 108 before estrus, 2.4 ± 0.9 mL and 5.7 ± 0.9 × 108 during estrus, and 1.3 ± 0.3 mL and 8.1 ± 1.7 × 108 after estrus, respectively. The semen volume, sperm count, and testis volume markedly differed from 90 days before estrus until 66 days after estrus, whereas no marked differences in sperm motility, sperm viability, and proportion of morphologically abnormal spermatozoa were observed. Plasma testosterone concentrations were elevated both before and during estrus (0.62 ± 0.23 ng/mL and 0.95 ng/mL), but decreased substantially after estrus (0.20 ± 0.0 ng/mL). We inferred that spermatogenesis was active in this male panda from approximately 3 months before estrus to 2 months after estrus in the adjacent female.