This paper describes the frequency of multiple ovulations in 3631 mares, slaughtered in Pelotas - RS, predominantly from Crioulo breed. The higher frequency of multiple ovulation ocurred in February (19%), decreasing progressively up to September (0.4%). This result shows that the photoperiod has a positive influence on the ovarian activity, even on the number of ovulations per cycle. The overall mean of multiple ovulation was 7.1% (257/3631). Double ovulations ocurred in 6.5% (235/3631), triple in 0.5% (19/3631) and quadruple in 0.1% (3/3631). The months from December to April presented the highest frequencies over all multiple ovulations (65.5%). These observations may represent an importante support to reproductive management of the Crioulo breed in order to control the serious problem that represents twin pregnancies in equine.
multiple ovulations; mares; fertility; Crioulo breed
