Effect of mare status on fertility of inseminated mares with jackass semen diluted and cooled at 5 °C for 12 hours

The effect of the mare status on fertility of mares inseminated with diluted, cooled and stored jackass semen, was studied. The cycles were controlled by transrectal palpation and teasing, and mares were inseminated every Tuesday, Thursday and Saturday, from the detection of a follicle with 3.0 to 3.5cm diameter in one of the ovaries until ovulation. The semen of five Pega jackasses was diluted in skim milk-glucose or in egg yolk-glycine extender and cooled at 5 degrees C for 12 hours, with the inseminate dose of 400 x 106 motile spermatozoa (at the moment of the final dilution, before cooling). The inseminations were carried out in the uterine body. Pregnancy was detected using transrectal palpation, teasing and ultrasound exams every 14 days. The results of 195 cycles of 141 mares were grouped according to the mare status: maiden, barren, lactation or in foal heat. Pregnancy rates for the first cycle were 60.00%, 48.28%, 75.00% and 47.17%, and after four cycles, the pregnancy rates/cycle were 61.54%, 47.13%, 54.76% and 47.17%, respectively for maiden, barren, lactation and in foal heat mares (P>0,05). The mare status did not affect pregnancy rates of mares inseminated with diluted and cooled jackass semen and were efficient to use on reproduction.