The methods for collecting and freezing deer semen have been, for the most part, limited to two species; red deer ( Cervus elaphus) and fallow deer ( Dama dama) (Asher et al., 2000 Anim. Reprod. Sci. 62, 195–211). The object of this study was to evaluate the progressive motility and effects of a thermal stress test on white-tailed deer (WTD) semen frozen in Biladyl extender (Mini Tube, Verona, WI, USA). Semen was collected by electroejaculation from WTD bucks (n=7, ages 1.5–2.5 years) during the breeding season. This trial was the second collection for one buck (#0025) and the third collection for the other 6 bucks. The bucks were immobilized with a xylazine/ketamine mixture i.m. (2mgkg−1 Vedco, Inc., St. Joseph, MO, 2.2mgkg−1 ketamine HCl, Fort Dodge Animal Health, Fort Dodge, IA, USA) and electroejaculated with a Pulsator IV unit (Lane Manufacturing, Denver, Co). Semen was extended 1:1 with Biladyl A, and then slowly cooled to 4°C. Once cooled, semen was extended with equal amounts of Biladyl part A, then part B, to a final concentration of 160×106cells/mL. The extended semen was then loaded into 0.25-cc straws, placed over liquid nitrogen (LN2) in vapors (−80°C) for 10min, and then plunged into LN2. Straws were stored in a LN2 tank for 3 months. Semen was thawed in a 38.5°C water bath for 45s, then placed in a warm test tube and incubated at 38.5°C for 5min before progressive motility was evaluated using a computer program (Sperm Vision, Mini Tube). A thermal stress test was performed by incubating thawed samples at 38.5°C for 1h. Results of the stress test were graded as either passed (progressive motility ≥50%) or failed (progressive motility<50%). Results are shown in the table below. Our results show that the protocol described above is suitable for the cryopreservation of white-tailed deer semen. These data suggest that the initial post-thaw progressive motility may not accurately represent the potential progressive motility of the spermatozoa (e.g. WTD s 0038 & 0103).
Table 1
Volume collected and post thaw evaluation of white-tailed deer semen
124CRYOPRESERVATION OF WHITE-TAILED DEER (ODOCOILEUS VIRGINIANUS) SEMEN
