The objective of this study was to evaluate different osmolarities and incubation times during the hiposmotic test and its correlation with cryopreservation of semen of Zebu bulls. It was used 30 ejaculates from six mature Nelore bulls. It was performed physical and morphological evaluation, supravital staining classification and hiposmotic test in the fresh semen. In the hiposmotic test, solutions with osmolarities of 60, 100, 150 mOsm/kg and distilled water (19 mOsm/kg) were used at 15, 30 and 60 minutes of incubation at 37ºC. After cryopreservation, the samples were thawed and evaluated for hiposmotic test, supravital staining, slow termoresistance test and for fluorescent stain. No interactions were detected between incubation times and solution osmolarities. There were no differences in average values of reactive sperm incubated in different solutions with different osmolarities for frozen/thawed semen. Only the use of distilled water determined differences in the average values obtained in the hiposmotic test performed in fresh semen. There was no difference between the mean values of reactive spermatozoa incubated with different incubation time in both fresh and frozen/thawed semen. Hiposmotic test can be accomplished in 15 minutes of incubation time and with a solution which varies osmolarity from 60 to 150 mOsm/kg in both fresh and frozen/thawed semen.
Bos indicus; complementary tests; cryopreservation; spermatozoa
