183 IN VITRO EMBRYO PRODUCTION: A TOOL TO PRESERVE THE THREATENED WOOD BISON (BISON BISON ATHABASCAE)
M. P. Cervantes A , J. M. Palomino A , M. Anzar A B , R. J. Mapletoft A , G. Mastromonaco C and G. P. Adams AA University of Saskatchewan, Saskatoon, Saskatchewan, Canada;
B Agriculture and Agri Food Canada, Saskatoon, Saskatchewan, Canada;
C Toronto Zoo, Toronto, Ontario, Canada
Reproduction, Fertility and Development 28(2) 222-222 https://doi.org/10.1071/RDv28n2Ab183
Published: 3 December 2015
Abstract
In vitro embryo production is being developed as a tool to restore genetic diversity and eliminate endemic disease in wood bison. In a recent study in wood bison, we found that more oocytes reached maturity after 30 h v. 24 h of in vivo maturation following hCG treatment (Cervantes et al. 2014 Reprod. Fertil. Dev. 26, 199). An additional 4 h of in vitro maturation after an in vivo maturation period of 30 h also had a positive effect on developmental competence. The present study was designed to test the hypothesis that extending the in vivo maturation time (i.e. extending the interval between hCG treatment and cumulus-oocyte complex (COC) collection) from 30 to 34 h will improve in vitro embryo production in wood bison. Follicular wave development was synchronised among female wood bison (n = 28, 6 to 10 years old) by transvaginal follicular ablation. The study was done in 4 replicates (n = 7 bison per replicate). Bison were given FSH 1 day (300 mg) and 3 days (100 mg) after ablation for ovarian superstimulation, and hCG (2500 IU) 5 days after ablation to induce COC maturation in vivo. Bison were divided randomly into 2 groups (n = 14/group) in which COC were collected transvaginally at either 30 h or 34 h after hCG treatment. Expanded COC from the 30 h group were fertilised after 4 h of in vitro maturation, while expanded COC from the 34 h group were fertilised immediately. Oocytes and sperm were co-incubated (Day 0 = day of fertilization) for 18 h at 38.5°C in 5% CO2 in air and high humidity. Presumptive zygotes were cultured in 4-well dishes containing 500 μL well–1 of CR1aa medium at 38.5°C, 5% CO2, 5% O2, 90% N2 and high humidity, and assessed on Days 3, 7, and 8 (Day 0 = day of fertilization). Data were compared between groups by Chi-squared analysis. No effect of replicate was found. Compared to the 30 h group, the 34 h group had a greater cleavage rate [55/74 (74%) v. 49/86 (57%); (P < 0.05)], and a greater blastocyst rate on Day 7 [25/74 (34%) v. 9/86 (10%); (P < 0.05)] and Day 8 [(40/74 (54.1%) v. 32/86 (37.2%); (P < 0.05)]. We concluded that an extended period of in vivo maturation is beneficial for embryo production after in vitro fertilization in wood bison.
We thank Vetoquinol Canada for providing FSH (Folltropin-V) and hyaluronan (MAP-5) and thank Merck Animal Health for hCG (Chorulon).
