Vitrification of White-tailed Deer (Odocoileus virginianus) oocytes with sucrose or trehalose for in vitro maturation and fertilization.

Objective: Evaluate the White-tailed Deer (WTD) in vitro embryo production (IVP) and oocytes vitrified with Trehalose (TH) or Sucrose (SC). Design/methodology/approach: Total vitrified oocytes were placed into two different groups: TH (n=60) and SC (n=61). Samples were selected and analyzed for viability evaluation TH (n=5) and SC (n=5), nuclear status (NS) TH (n=4) and SC (n=5), Germinal Vesicle (GV), Metaphase I, or not evaluable (NE) after warming. In vitro maturation (IVM) was conducted for 36 h in supplemented TCM-199 medium. Immediately afterwards, oocyte NS was evaluated (n=88) [(GV, MI=immature), (MII=mature)]. In vitro fertilization (IVF) was performed in supplemented TALP medium for 24 h using frozen WTD semen (3x106 sperm/mL), NS was classified [Fertilized (F), Not fertilized (NF), or NE]. Results: After warming, viability for the TH group (n=5) was 60% versus 40% for SC group (n=5), however, oocytes in both groups were immature (GV and MI stage). For IVM, NS evaluations of the TH group (n=38) revealed no maturation versus 2% in the SC group (n=50) (MII stage=matured). IVF evaluations for the TH group (n=10) revealed no fertilization compared to 20% in the SC group (n=5). A statistical difference (p>0.05) was not found between the TH and SC groups. Limitations on study/implications: White-tailed Deer in vitro embryo production is not well documented. Findings/conclusions: Future research with a larger number of WTD oocytes is needed for further evaluation of oocyte vitrification IVP techniques as a model for endangered cervids