Characterization of basal seminal traits and semen cryopreservation in Canada lynx (Lynx canadensis)

Abstract

Little is known about the reproductive biology of the Canada lynx; virtually no data are available describing seminal parameters in this species and sperm cryopreservation studies have not been performed. Our aims were to 1) evaluate effectiveness of two semen collection methods: urethral catheterization (UC) and electroejaculation (EEJ); 2) characterize basal seminal traits throughout the breeding season; 3) compare effectiveness of semen cryopreservation using TEST egg yolk (TEY) or soy lecithin-based (SOY) media; and, 4) evaluate the ability of preserved Canada lynx sperm to fertilize domestic cat in vitro matured oocytes by heterologous in vitro fertilization. Testicular volume averaged 4.5±1.0 cm³. A significant relationship was found between animal body weight and testes volume (P<0.02), as well as for testicular volume and sperm counts per ejaculate (P<0.01). Fecal testosterone concentrations and sperm production were correlated (P<0.01). Electroejaculation was more reliable than UC for sperm collection (8.8 and 1.5 × 10⁶ sperm, respectively; P<0.01). The percentage of sperm with normal morphology was greater in EEJ (29 ± 11 %) than in UC (18 ± 9 %) (P<0.05) samples and primary sperm structural abnormalities were more frequent in UC than EEJ samples (P<0.01). Overall, sperm quality was low in most males throughout the breeding season, but consistent with previous findings in the Lynx genus. Sperm production averaged 10.8 × 10⁶ sperm/ejaculate with 45 % motility; 29 % normal morphology and 69 % acrosome integrity. Motility and acrosome integrity post-thaw declined over time, but were similar between spermatozoa cryopreserved in TEY and SOY media (P > 0.05). Cleavage rates did not differ between TEY (29 ± 17 %) and SOY (27 ± 14 %) and mean numbers of sperm bound to the zona pellucida was similar (20 sperm, TEY vs. 18 sperm, SOY), indicating that both extenders equally preserved the function of Canada lynx sperm for semen banking purposes. Our findings provide zoos and population managers with valuable information about normative reproductive traits in this species, establishing comparative benchmarks for assessing the reproductive potential of specific males recommended for breeding.