Sperm storage of wild cervid species: comparison of available cryoprotectants

Abstract

We compared four diluents (Andromed, dimethylacetamide, dimethyl sulphoxide, Triladyl) used for semen cryopreservation in wild ungulates from the family Cervidae, i.e. roe deer (Capreolus capreolus), red deer (Cervus elaphus), and fallow deer (Dama dama). Epididymal sperm samples were collected and analysed immediately using Computer Assisted Sperm Analysis with the module for concentration and motility determination and, after equilibration, frozen and placed in liquid nitrogen for one month. After thawing, the samples were again subjected to the same examination procedure. Influence of cryopreservation and choice of the cryoprotectant was assessed by monitoring sperm concentration, average head area (HA), average velocity and progressivity (VAP), beat frequency (BF), total motility (MO), total progressive motility (PR), circular tracks (CT) and mucous penetration (MP). We observed no significant differences in sperm concentration between cryoprotective diluents or fresh and post-thaw samples in all species. All motility indicators (MO, PR, VAP, BF, CT) were influenced by the treatment but did not differ significantly between diluents used in red and roe deer. In fallow deer, commercial diluents (Andromed, Triladyl) resulted in better sperm survival than the alternatives (dimethyl sulphoxide, dimethylacetamide). Only HA showed significant differences (P < 0.001) in all species based on the diluent, with no effect of treatment. In contrast, MP was influenced by both the diluent and the cryopreservation process in roe deer and, partly, fallow deer. In future studies, we suggest expanding both the members of the Cervidae family examined and the sample size. Knowledge how to optimise cryopreservation protocols for different mammalian species has implications for conservation reproductive medicine of endangered wildlife.