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RESEARCH ARTICLE

Supplementation of culture medium with L-carnitine improves the development and cryotolerance of in vitro-produced porcine embryos

J. L. Lowe A , L. K. Bartolac A , R. Bathgate B and C. G. Grupen A C
+ Author Affiliations
- Author Affiliations

A Faculty of Veterinary Science, The University of Sydney, 425 Werombi Road, Camden, NSW 2570, Australia.

B Faculty of Veterinary Science, The University of Sydney, Regimental Drive, NSW 2006, Australia.

C Corresponding author. Email: christopher.grupen@sydney.edu.au

Reproduction, Fertility and Development 29(12) 2357-2366 https://doi.org/10.1071/RD16442
Submitted: 4 November 2016  Accepted: 14 March 2017   Published: 10 April 2017

Abstract

Porcine oocytes and embryos contain substantial amounts of lipid, with little known regarding its metabolic role during development. This study investigated the role of lipid metabolism and the interaction between carbohydrate and lipid substrates in porcine embryos. Following in vitro fertilisation, presumptive zygotes were transferred to culture medium supplemented with L-carnitine, a co-factor required for the metabolism of fatty acids. In porcine zygote medium-3 (PZM-3), which contains pyruvate and lactate, 3 mM L-carnitine was the only dose that improved cleavage rates compared with the control. In the absence of carbohydrates, all doses of L-carnitine from 1.5 to 12 mM increased cleavage rates compared with the control. Culture in a PZM-3-based sequential media system (Days 0–3: pyruvate and lactate; Days 4–7: glucose) significantly increased blastocyst cell numbers compared with culture in standard PZM-3. Supplementing PZM-3 with 3 mM L-carnitine produced blastocysts with cell numbers equivalent to those obtained in the sequential media system. After vitrification, the post-warming survival rates of blastocysts obtained in media supplemented with 3 mM L-carnitine were significantly greater than those of blastocysts obtained in standard PZM-3. In conclusion, L-carnitine supplementation improved embryo development when the medium contained pyruvate and lactate or was lacking carbohydrates completely, indicating a role for fatty-acid metabolism when the embryo’s requirements for carbohydrates are not adequately met.

Additional keywords: blastocyst, carbohydrate, lipid, vitrification.


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