101 Assessment of semen traits in servals (Leptailurus serval) and Canada lynx (Lynx canadensis)

Abstract

Servals and Canada lynx are managed by species survival plans in North American zoos, but current populations are not sustainable. Increased knowledge of their reproductive biology would benefit breeding management and development of assisted reproductive techniques. The aims of our study were to (1) evaluate effectiveness of urethral catheterization and electroejaculation (EEJ) for semen collection; (2) characterise basal seminal traits; and (3) compare effectiveness of semen cryopreservation methods. Semen was collected from 6 servals and 9 Canada lynx via a urinary catheter (3.5 Fr × 22 cm, inserted 15 cm into the urethra), followed by EEJ under dexmedetomidine-ketamine anaesthesia. To assess the effect of seasonality on lynx seminal traits, semen was collected before (late January), during (mid-February to mid-March), and after (early April) the peak breeding season. Serval and lynx semen were frozen by conventional slow freezing (i.e. in 0.25-mL straws cooled to 4°C for 2 h and frozen in LN vapor) in a soy lecithin-based (SOY) or egg yolk-based (TEY) extender with 4% glycerol and by ultra-rapid freezing (URF; direct pelleting into LN at ≈10⁴ °C/min) in SOY medium with 0.2 M sucrose. To evaluate post-thaw sperm function in servals, heterologous IVF of domestic cat oocytes was performed, with cleavage rate assessed at 48 h post-insemination. Data were analysed by one-way or repeated-measures ANOVA. Data are mean ± standard deviation. Sperm recovery by urethral catheterization was negligible in both species, but EEJ allowed sperm collection in all males. Lynx seminal traits were similar during breeding and nonbreeding seasons. Testicular volume (4.81 ± 1.17 cm³) and sperm quality (13 ± 11 × 10⁶ sperm/ejaculate; 49 ± 14% motility; 29 ± 12% normal morphology; 74 ± 13% acrosome integrity) were consistent with previous findings in the lynx genus. Post-thaw sperm quality in lynx has not yet been evaluated. In servals, testes volume was 6.56 ± 2.11 cm³ with good sperm quality for most males (46 ± 36 × 10⁶ sperm/ejaculate; 75 ± 20% motility; 56 ± 36% normal morphology; 84 ± 7% acrosome integrity). Post-thaw, serval sperm acrosome integrity (31 ± 15, 21 ± 13, 24 ± 13% at 0 h for TEY, SOY, and URF, respectively; P > 0.05) and motility (40 ± 21% at 0 h, 20 ± 11% at 6 h for TEY; 24 ± 19% at 0 h, 6 ± 4% at 6 h for SOY; 21 ± 16% at 0 h, 3 ± 2% at 6 h for URF; treatment: P > 0.05; time: P < 0.05; interaction: P > 0.05) declined substantially. However, thawed sperm could fertilize domestic cat oocytes with no difference among treatments in cleavage success (53 ± 6, 47 ± 4, or 49 ± 14%; TEY, SOY, and URF, respectively; P > 0.05), indicating that standard freezing methods are effective in servals. Our findings provide zoos with valuable information about normative reproductive traits in both species.

Supported by IMLS and the Roger & Kathy Gross Post-doctoral Fellowship.