Application of embryo biopsy and sex determination via polymerase chain reaction in a commercial equine embryo transfer program in Argentina.

This study examines the use of embryo biopsy and sex determination through polymerase chain reactions in a commercial horse embryo transfer program in Argentina. The researchers conducted biopsies on embryos and determined their sex, finding that the technique did not significantly reduce pregnancy rates and that the efficacy varied based on the size of the embryo and the time between collection and biopsy.

Objective of the Research

• The research was carried out to establish the success rate and practicality of embryo biopsy and fetal sexing through polymerase chain reaction (PCR) in a commercial equine embryo transfer program across one breeding season.

Methodology Used

• A number of 459 embryos were biopsied, and the researchers assessed the differences in pregnancy rates between biopsied and non-biopsied embryos as well as embryos recovered at the centre and those shipped overnight.
• A decrease was noticed in the pregnancy rate in embryos shipped for biopsy ≥20h after collection.
• The size of the embryo was considered, with the genomic (g) DNA result likelihood being considerably higher in larger blastocysts.

Results Obtained

• No significant difference observed in pregnancy rates between biopsied and non-biopsied embryos. The tally stood at 72% vs 73% with a slight edge to the latter.
• 86% of biopsies successfully provided a sex diagnosis.
• The rate for a positive gDNA result was significantly higher when sourced from larger blastocysts (96%) compared to smaller embryos (70-85%).
• Out of the total biopsies, 38% tested positive for Y chromosome DNA (Y-DNA) and were diagnosed as male.
• The study confirmed 95% of Y-DNA-positive embryos as male and 78% of Y-DNA-negative embryos as female.

Conclusions

• The likelihood of predicting a female embryo (Y-DNA negative) significantly increased when the biopsy sample was only probed for Y-DNA compared to probing for both gDNA and Y-DNA.
• The researchers estimated that by only transferring Y-DNA-negative embryos, a 3% reduction could have been witnessed in potential female pregnancies, with male pregnancies being reduced by 72%.