Seasonal variation in the endocrine–testicular function of captive jaguars ( Panthera onca)

Abstract

Captive adult male jaguars ( Panthera onca) from two locations in southeast Brazil were studied to evaluate the effects of season on endocrine and testicular function. For assessment of testicular steroidogenic activity, androgen metabolite concentrations were measured in fecal samples collected one to three times per week over 14 ( n=4), 9 ( n=1) or 7 months ( n=1). To assess seasonality, data were grouped by season (summer: December–February; autumn: March–May; winter: June–August; spring: September–November). Additionally, samples collected in the dry season (March–August) were compared with those collected in the wet season (September–February). There were no differences ( P>0.05) in fecal androgen concentrations in samples collected in spring, summer, autumn, and winter (480.8±50.4 ng/g, 486.4±42.0 ng/g, 335.4±37.7 ng/g, and 418.6±40.4 ng/g dry feces). However, there were differences ( P<0.05) in fecal androgen concentrations between the dry and wet seasons (380.5±28.0 ng/g versus 483.9±32.3 ng/g dry feces). Sperm samples, collected from all males twice (approximately 6 months apart) were similar; mean (±S.E.M.) motility, concentration and morphology were 57.0±4.5%, 6.3±2.4×10 6 ml −1, and 60.8±3.1%, respectively. In conclusion, androgen metabolite concentrations in the captive male jaguar were not affected by season, but there was a difference between the wet and dry periods. Further research is needed to verify these results.