Reproductive performance and disorders in mares

Reproductive performance and disorders were studied For thoroughbred mares from 1993 to 1996. The overall mean estrus cycle length (EL) and estrus per iod (EP) were 14.98+/-1.12 and 6.04+/-0.248 days. Both EL and EP did not va ry between the years, but differed significantly between the months (P<0.05 ). The overall mean coverings required per foal born were 9.87. Maximum foa lings occurred in April (19) followed by March (18), February (14), May (11 ) and June (2), 64.61% of the foalings occurring at night to mid-night, 21. 53% at early morning and only 6.15% during day hours. Mares evidenced foal heat with an interval of 7.78+/-0.72 days after foaling in 56.92% cases. Th e abortion per cent was 13.15, 40% of th, total abortions being due to twin ning. The sex ratio was 43.07% male births. Reproductive disorders were unc ommon, there were 4.61, 0.71, 4.28 and 3.57% cases of placental retention, vaginitis, pneumovagina and anestrus.