Long-term liquid storage of porcine spermatozoa separated using a discontinuous bovine serum albumin gradient.

Abstract

Two experiments were conducted to determine efficacy of a discontinuous bovine serum albumin (BSA) gradient for isolating viable porcine spermatozoa more tolerant to 5-d liquid storage in Beltsville Thawing Solution (BTS) at 15 degrees C. The gradient, contained in a 500-ml separatory funnel, consisted of 4% BSA (60 ml) over 10% BSA (60 ml). Spermatozoa were extended in 26 ml of BTS, layered on top of the gradient, and allowed to migrate through the BSA. The quality of spermatozoa separated by the gradient varied among boars. However, populations of spermatozoa isolated from the bottom 30 ml of the gradient (Fraction 4) consistently contained a high percentage of spermatozoa with acrosomes possessing normal apical ridges (NAR; 89.6%) and progressively motile spermatozoa (MOT; 84.0%), as well as spermatozoa with high velocity (VEL; 336.5 mu/s). Increasing sperm migration time, but not gradient temperature, increased the number of spermatozoa recovered in Fraction 4, but it did not reduce quality of the separated spermatozoa. Spermatozoa isolated in Fraction 4 had greater NAR, MOT and VEL after 5-d storage in BTS than did unseparated spermatozoa. Boar spermatozoa isolated on a discontinuous BSA gradient were more tolerant to storage at 15 degrees C than were unseparated spermatozoa. Such a population may be desirable for use in artificial insemination programs.