Efeito da concentração espermática e do número de inseminações artificiais sobre a fertilidade de éguas inseminadas com sêmen fresco diluído

This work aimed to study the effects of spermatic concentrations (200× 106 and 400×106 spermatozoa/inseminated dose) and number of inseminations (two, three and four or more) on the fertility of 62 mares (military type). Mares were teased and inseminated on Mondays, Wednesdays and Fridays with diluted semen from only one stallion of proven fertility. The conception rates during the first cycle for the two spermatic concentrations were, respectively, 66.7%(20/30) and 65.5%(19/29) and after four cycles they were, respectively, equals to 52.0%(26/50) and 57.8%(26/45) with no difference on conception rate according to the spermatic concentrations (P>0.05). The conception rates for the first cycle after two, three and four or more inseminations were, respectively, 72.0%(18/25), 65.2%(15/23) and 54.6%(6/11) and after four cycles they were, respectively, equals to 59.0%(23/39), 52.5%(21/40) and 50.0%(8/16) with no differences on conception rates according to the number of inseminations. The results suggested that mares could be inseminated using a spermatic concentration of 200×106/inseminated dose on Mondays, Wednesdays and Fridays without any loss of fertility independently of the number of inseminations/cycle.