Influence of season on seminal characteristics, testis size and serum testosterone in the western spotted skunk (Spilogale gracilis)

in Reproduction

The western spotted skunk is a seasonally breeding mammal: most copulations occur in late September and early October. This study was performed to characterize the seasonal changes in concentrations of testosterone and in ejaculate quality. Captive males (n = 22) were maintained on a natural photoperiod for 15 months. Semen samples were collected by electroejaculation; testis size was measured; and blood samples were collected. Of 110 electroejaculation attempts, 104 (95%) resulted in successful fluid collection and 101 (97%) samples contained spermatozoa. Significant increases (P < 0.05) in serum testosterone concentration, testis size and ejaculate volume were observed from August to November. Mean concentration of testosterone in serum ranged from 0.15 ± 0.05 ng ml−1 in mid-January to 6.42 ± 1.79 ng ml−1 in early October. Mean testis size ranged from 1.22 ± 0.25 cm2 in February to 2.68 ± 0.08 cm2 in October. Mean ejaculate volume ranged from 11 ± 3 μl in March to 129 ± 22 μl in October. Seasonal changes in the number of spermatozoa per ejaculate or motility of spermatozoa were not observed. Mean number of spermatozoa per ejaculate was 8.14 ± 0.85 × 106 spermatozoa (n = 97); motility was 56 ± 2.4% (n = 93); semen pH was 7.76 ± 0.20 (n = 6); osmolarity was 394 ± 13 mmol kg−1 (n = 10); and 70.3 ± 1.5% of the spermatozoa were morphologically normal (n = 47). Concentration of testosterone in serum was highly correlated with testis size (r = 0.484, P < 0.001, n = 137), but none of the semen characteristics was found to be correlated with either concentration of testosterone in serum or testis size (P > 0.05). These data suggest that concentration of testosterone in serum, testis size and ejaculate volume increase seasonally as photoperiod decreases.

 

An official journal of

Society for Reproduction and Fertility

Index Card

PubMed

Google Scholar

Related Articles

Altmetrics

Metrics

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 64 64 26
PDF Downloads 55 55 8