Effect of Photoperiod Extension on the Testicular Sonographic Appearance andSexual Behavior of Captive Yangtze Finless porpoise (Neophocaena asiaeorientalisasiaeorientalis)

摘要

Photoperiod playsan important role in the seasonal regulation of reproduction in mammals. In the presentstudy, we examined the effect of an extended photoperiod (light/dark: 14 h/10 h) duringthe usual sexually inactive phase (Jan-Mar) on testicular sonographic appearance andsexual behaviors of two captive Yangtze finless porpoise ( , YFP). During the extended photoperiodtreatment, the parenchyma pixel intensity, cross- sectional area of testicular sonographicimages, as well as the frequency of sexual behaviors of the two male porpoises increasedsignificantly compared to the control treatment. Parenchyma pixel intensity, the cross-sectional area of testicular sonographic images and the frequency of sexual behaviors ofthe two captive males all increased in response to extended photoperiod. These results maysuggest that photoperiod is a potent factor regulating the reproductive seasonality inYFPs.