Impact of reproductive biotechnologies on genetic variability of Argentine Polo horses

•More than 60% of Argentine Polo horses are produced by embryo transfer (ET).•Inbreeding, average relatedness and coancestry coefficient were higher in horses born by ET than by natural pregnancy, while the effective number of founders and ancestors was lower in ET-horses.•Genetic variability was highly reduced by ET.•ET increased genetic flow and reduced the generation interval, contributing to the possibility of higher rates of genetic progress in Argentine Polo horses.