Infertile mares with chromosome abnormalities

Abstract

Chromosomal abnormalities have been detected in five mares identified by their poor reproductive performance. All had small gonads and absent or irregular oestrous cycles. One mare was 65, XXX, two were 64, XY sex-reversal females and two were sex chromosome mosaics with karyotypes of 63, XO/64, XX/64, XY and 63, XO/64, XX respectively. This report supports the suggestion made in earlier studies that sex chromosome abnormalities may be a significant cause of sterility in the mare.