Reproductive maturation in the male Eurasian lynx (Lynx lynx): a study on 55 reproductive organs collected from carcasses during 2002-2005.

Data on reproductive physiology from the Eurasian lynx (Lynx lynx) are still scarce. The lynx is protected under Swedish hunting legislation. All lynx that are found dead or that are culled at hunting are to be sent to the Swedish National Veterinary Institute. In this study, we examined reproductive organs from 55 male lynx collected during the years 2002-2005. Age, body weight, testicular weight and volume, production of spermatozoa, and sperm viability were evaluated. The majority of the animals (39) had been killed in February and March, which is during the hunting season. The ages varied between 6 months and 17 years, body weight between 3.6 and 25.5 kg, and mean testes weight between 0.16 and 3.16 g. The gonadosomatic index was low compared with other species (approximately 0.02% in mature males). Mean testes weight differed significantly between males <12 months of age and all other age groups but did not differ between males of 18-23 months and older males. Spermatozoa could be collected but had lost most of their viability. Seven of 10 males of 18-23 months were fertile, as defined by the production of spermatozoa while no males < or =15 months of age were fertile. Adherence of the prepuce to the penis and absence of penile spines were associated with immaturity. The results indicate that most males are fertile during the reproductive season of their second year.