32 The efficiency of an adapted bovine IVF protocol to produce in vitro-derived embryos from oocytes collected via surgical ovum pickup from live white-tailed deer (Odocoileus virginianus) donors under captivity in central Illinois

Critical studies on in vitro embryo production (IVEP) in white-tailed deer (WTD) (Odocoileus virginianus) have not been reported. However, the aim of this study was to determine the use and efficiency of an adapted, commercial bovine IVEP protocol to produce in vitro-derived embryos from oocytes collected via surgical ovum pickup from live WTD does under captivity in central Illinois. A total of 6 donor animals, over two replicates (replicate 1: n = 2 and replicate 2: n = 4), were used in this study. The oestrous cycles of the does were synchronized by placing a small ruminant controlled internal drug release (CIDR) device 14 days before the surgical ovum pickup, and upon removal of the CIDR, 0.05 mg FSH α+WT β protein were administered 2 days before the surgical ovum pickup. The oestrus synchronization and superstimulation were used to more precisely time the surgical ovum pickup and to increase the number of follicles that could be aspirated. Purchased, nongender selected buck semen from two males was used for IVF. Semen from buck 1 was used to fertilize oocytes in replicate 1 likewise, semen from buck 2 was used to fertilize replicate 2. Cleavage and blastocyst rates were evaluated on Days 3 and 7, respectively. A total of 45 immature oocytes (replicate 1: 27; replicate 2: 18) were recovered from the does. Total and viable oocytes per donor averaged 7.5 and 6.33 respectively. Viable oocytes were defined as oocytes with at least one layer of cumulus cells surrounding the oocyte. The total percentage of viable oocytes was 80% based on morphology (Table 1). We calculated chi squares for the data set resulting in a blastocyst rate that was higher for replicate 2 (61.11%) than replicate 1 (33.33%). Though the P-values for cleavage and blastocyst production showed no difference between replicates (cleavage, P = 0.26; blastocyst, P = 0.07). In conclusion, a cleavage rate of 62.22% and a blastocyst rate of 44.44% were achieved with 45 immature oocytes collected via surgical ovum pickup. Furthermore, 20 embryos were produced using a commercial bovine IVF protocol adapted to have 24 h of fertilization (as opposed to 18–22 h of fertilization). Overall, the adapted protocol produced blastocyst and cleavage rates for WTD similar to those achieved when using the protocol on cattle. With continued adjustments, the protocol could be optimized for IVF embryo production in WTD.