54 CRYOPRESERVATION OF BOVINE IN VITRO-PRODUCED EMBRYOS: INTRINSIC FACTORS DETERMINING VITRIFICATION OUTCOMES
M. N. Saucedo A , M. Kurome A , M. Reichenbach B , E. Wolf A and H.-D. Reichenbach CA Chair for Molecular Animal Breeding and Biotechnology, LMU, Munich, Oberschleissheim, Germany;
B Bayern Genetik GmbH, Grub, Germany;
C Institute for Animal Breeding, Bavarian State Research Center for Agriculture, Grub, Germany
Reproduction, Fertility and Development 27(1) 120-120 https://doi.org/10.1071/RDv27n1Ab54
Published: 4 December 2014
Abstract
As a part of a study on bovine embryo genomic evaluation, effects of an intact (iZP) or opened zonae pellucidae (oZP) of in vitro-produced embryos on vitrification outcomes were assessed. In the first experiment, only iZP embryos were subjected to vitrification, using either the hollow fibre vitrification method (HFV; Matsunari et al. 2012 J. Reprod. Dev.) or the cryologic vitrification method (CVM; CryoLogic®, Blackburn, Victoria, Australia). Developmental stage (morula = M; early blastocyst = EaB; blastocyst = B) and quality (good = 1; fair = 2) before vitrification were evaluated. In a first set of experiments, quality 1 and 2 iZP embryos were vitrified either by the HFV or the CVM method. A significant difference between the 2 methods was found when comparing overall survival rates (24–48 h post-thaw; HFV 59.32% v. CVM 78.9%; P < 0.001; unpaired t-test, GraphPad Prism, GraphPad Software Inc., La Jolla, CA, USA). Concerning hatching rates, no significant difference was found (HFV 48.7% v. CVM 57.8%; P > 0.1). In order to evaluate influence of embryo stage and quality on HFV or CVM outcomes, iZP embryos vitrified by the HFV method were classified regarding quality (1: n = 207; 2: n = 66; total n = 273) and embryo stage (M: n = 78; EaB: n = 74; B: n = 121). Concerning survival rates, no significant difference was found between M 1 (57.4%) and M 2 (44.6%), or EaB 1 (80%) and EaB 2 (68%). However, a significant difference was found when comparing B 1 (77%) and B 2 (29%; P < 0.05). With regard to hatching rate, no significant difference was found between M 1 (39.9%) and M 2 (30%), or EaB 1 (66.6%) and EaB 2 (57%). However, significant difference was found between B 1 (60.9%) and B 2 (22%; P < 0.05). With regard to the CVM (1: n = 172; 2: n = 82; total n = 254), no significant difference was found when analysing survival rates of EaB 1 (82%) and EaB 2 (80%), or B 1 (87%) and B 2 (74%), whereas the survival rates were significantly different between M 1 (80%) and M 2 (53%; P < 0.05). Significant differences regarding hatching rates were not found between M 1 (51%) and M 2 (28%) or EaB 1 (55%) and EaB 2 (65%), whereas the hatching rate of B 1 (76%) was not significantly higher than that of B 2 (48.8%; P < 0.05). In a second set of experiments, oZP EaB (1: n = 14) and oZP B (1: n = 30) were vitrified by the CVM method. No significant difference regarding survival rates concerning stage (95 and 72%, EaB and B, respectively), or between treatments (EaB iZP v. oZP, and B iZP v. oZP; P > 0.1) was found. Effect of ZP, either intact or opened, does not seem to affect survival rates (judged by their re-expansion 24–48 h post-thaw) of good-quality embryos.
The authors thank the Bavarian Research Foundation for the financial support (AZ-1031-1; DOK-153-12).
