Effect of L-glutamine for freezing equine embryos: evaluation by DAPI staining and transfer of multiple embryos to recipient mares.

This study examines the impact of L-glutamine on the freezing and successful transplantation of equine embryos, finding that higher concentrations of this amino acid seem to enhance the survival rate of these embryos during the freezing process.

Research Context

• The research is focused on the preservation and transplantation of equine embryos – often a critical aspect of horse breeding and conservation.
• The success of these processes often depends on the survival of embryos during freezing, and the study explores different concentrations of L-glutamine in the freezing medium and how it may impact this survival rate.

Methodology

• Experiments were performed on equine embryos (n=30) that were frozen in a medium containing glycerol and supplemented with varying levels of L-glutamine: 0, 20, or 100 mmol L-glutamine 1(-1).
• After defrosting, the embryos were individually assessed for cell death using 4′,6′-diamidino-2-phenylindole (DAPI) staining, a procedure typically used to detect DNA in cells.
• Furthermore, three embryos, each frozen at one of the three L-glutamine concentration levels, were grouped collectively and implanted into recipient mares. Pregnancy was determined on the 12th day after transfer, and the embryos were gathered back two days later for identification through PCR-amplified microsatellite analysis.

Findings

• Nine out of ten recipient mares ended up pregnant, with one mare carrying two embryos and the others each carrying a single embryo.
• Notably, the success rate of the pregnancies was significantly higher (6 out of 10 pregnancies) when the embryos had been frozen in a medium with 100 mmol L-glutamine l(-1).
• Lower successful pregnancy rates were observed for embryos frozen in medium with 20 or 0 mmol L-glutamine l(-1) (1 of 10 and 3 of 10 pregnancies, respectively).
• The DAPI staining findings indicated lower fluorescence – and thus, lower cell death – among embryos frozen in medium containing 100 mmol L-glutamine l(-1), revealing greater survival rates than those observed with lesser concentrations of L-glutamine.

Takeaway

• In summary, the study finds that higher concentrations of L-glutamine in the freezing process can improve the survival of equine embryos, potentially enhancing the success rates of equine embryo transfers. This understanding could offer better practices in equine breeding and conservation programs.