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Comparison of pregnancy in cattle when non-vitrified and vitrified in vitro-derived embryos are transferred into recipients

journal contribution
posted on 2018-10-05, 00:00 authored by Van Huong Do, S Catt, G Amaya, M Batsiokis, S Walton, Andrew Taylor-Robinson
The present study was conducted in cattle to test the null hypothesis that the pregnancy rate of recipient females is similar when in vitro-derived embryos are transferred either fresh (non-vitrified) or after being subjected to vitrification. Cumulus-oocyte complexes, collected twice (6 weeks apart) from 10 donor cows were matured in vitro and inseminated with frozen-thawed sperm from a single proven bull per donor collection. Cleaved embryos were cultured in vitro until day 7 and any resulting blastocysts were graded for stage [early (unexpanded), advanced (expanded, hatching, hatched)] and/or quality and either discarded (poor quality), or, if deemed suitable, transferred fresh or vitrified for later warming and transfer. All blastocysts were transferred singly to oestrus-synchronized cows and pregnancy monitored by transrectal palpation on days 35, 60 and 90. From 20 collections, 818 cumulus-oocyte complexes were aspirated; however, after grading, only 462 (56.5%) were ranked as suitable quality for maturation and insemination. From those 462 complexes inseminated, 363 (78.6%) cleaved during the process and 243 (52.6%) developed to the blastocyst stage with 194 (42.0%) deemed utilizable, of which 85 were vitrified and 109 were transferred fresh. There was a median of 13 (range 0e24) utilizable blastocysts per cow. Of the 109 non-vitrified blastocysts transferred, there were 45 (41.3%) and 41 (37.6%) recipients that were detected to be pregnant on day 35 and day 90, respectively, subsequent to transfer. Thus, an 8.9% abortion rate was observed (4/45). Of the 85 transferred vitrified-warmed blastocysts, 34 were detected to be pregnant (40.0%) on day 35 following transfer, and all pregnancies were maintained at day 90 (0% abortion rate), which was similar to non- vitrified transfers (P > 0.05, Chi-square test). There was no significant difference in pregnancy rate on day 90 in advanced compared to early blastocysts for either the non-vitrified transfers (9/23, 39.1% vs 33/86, 38.3%) or the vitrified transfers (30/72, 41.6% vs 4/13, 30.8%) (P > 0.05 in each case). In summary, these data show that vitrification of in vitro-derived early and advanced blastocysts is a suitable method of cryopreservation of bovine embryos, and, furthermore, that subsequent transfer of all vitrified/warmed blastocysts into recipient females results in pregnancy rates no different to those attained by non-vitrified transfers into recipient females.

Funding

Category 3 - Industry and Other Research Income

History

Volume

120

Start Page

105

End Page

110

Number of Pages

6

ISSN

0093-691X

Publisher

Elsevier, USA

Peer Reviewed

  • Yes

Open Access

  • No

Acceptance Date

2018-07-23

External Author Affiliations

National Institute of Animal Sciences, Hanoi, Vietnam; Department of Obstetrics & Gynaecology, Monash University, Clayton, VIC, 3168, Australia; Australian Reproductive Technologies, Mt Chalmers, QLD, 4702, Australia

Era Eligible

  • Yes

Journal

Theriogenology

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