Attempts to isolate highly viable, morphologically normal, Y- chromosome-bearing bovine spermatozoa

Five experiments were conducted to characterize a discontinuous bovine serum albumin (BSA) gradient and to determine its ability to isolate highly viable, morphologically normal, Y-chromosome-bearing bovine spermatozoa. The column consisted of a 500 ml separatory funnel in which 26 ml of extended semen was layered on top of a discontinuous gradient of 4% BSA (60 ml) over 10% BSA (60 ml). Results indicated that the greatest percentage of the applied semen was recovered from the bottom 20 ml of the gradient (fraction 6) when 1 x 10⁹ sperm cells were applied to the column. The column was able to exclude spermatozoa with midpiece and tail abnormalities but sperm cells with head abnormalities were similar in frequency in separated and unseparated semen. Semen isolated from fraction 6 was more viable and more resistant to damage by freezing and aging than semen from the top fractions of the column. The proportion of Y-chromosome-bearing spermatozoa isolated form fraction 6 did not differ from the proportion in unseparated semen. Cows inseminated with separated semen and unseparated semen gave birth to similar proportions of male and female calves.