Sixty two mares were randomly assigned to two experimental group, according to two intervals between the penultimate and the ultimate artificial insemination (48 or 72h). The mares were teased and inseminated on monday, wednesday and friday, when a follicle size was equal or greater than 3.0 cm in diameter, with semen from a stallion of proven fertility diluted with minimum contamination extender. The conception rates for the first cycle for the 48h and 72h intervals were 66.67% (24/36) and 65.22% (15/23) respectively, and the conception/cicle were 53.45% (31/58) and 56.76% (21/37), in the same order. Based on these results, one should consider recommending inseminations on monday, wednesday and friday, without fertility loss.
artificial insemination; interval of inseminations; mares
