Use of computer-assisted sperm analysis (CASA) to evaluate the quality of cryopreserved sperm in red seabream ( Pagrus major)

In the present study, the quality of post-thaw sperm of red seabream Pagrus major frozen with 6–24% DMSO was investigated. The motility, average path velocity and fertilizing capacity of fresh and their corresponding post-thaw sperm were examined for evaluation of the post-thaw sperm motion characteristics and its association with fertilizing capacity. An analysis of sperm motility before and after cryopreservation has been performed using computer-assisted sperm analysis (CASA). For post-thaw sperm frozen with 12–21% DMSO, the percentages of motile sperm were not significantly ( P > 0.05) changed 10 s after activation. Moreover, the main motility pattern and swimming velocity of the motile post-thaw sperm were not significantly ( P > 0.05) changed and the progressive linear motion was still the dominant pattern. However, the total motility of post-thaw sperm (72.3 ± 6.3%) 30 s after activation was ( P < 0.05) lower than the corresponding fresh sperm (82.7 ± 7.2%). Additionally, the fertilizing capacity of post-thaw sperm was investigated with a standardized sperm to egg ratio 500:1. There is a linear regression relationship between the percentage of motile post-thaw sperm and fertilizing capability. These data demonstrate that 12–21% DMSO can provide good protection to the sperm during the freezing–thawing process.