Sperm DNA Fragmentation after cryopreservation in meat type chicken breeders.

The comet assay or single cell gel electrophoresis (SCGE) has become a recognized method for detecting DNA damage in a variety of vertebrate cell types, including spermatozoa. The comet assay is used in several domestic animal species to investigate the potential damage induced by common semen handling practices, such as cryopreservation. The aim of the present study was to study DNA fragmentation in chicken spermatozoa after processing for cryopreservation, in F15 Hubbard strain selected for meat production. Semen collected from 7 males was diluted in modified Lake's pre-freezing extender, frozen in pellets and thawed in water bath at 60°C. Comet assay and viability (SYBR14-PI) were performed on fresh semen soon after collection and dilution, and after thawing. The proportion of spermatozoa with damaged DNA significantly increased from 5.7% (fresh semen) to 28.3% (frozen-thawed semen) during cryopreservation. The proportion of viable spermatozoa significantly decreased from 77.5% to 20.4% in fresh and frozen-thawed semen respectively. Sperm DNA damage was much lower compared to the decrease in viable sperm following cryopreservation, therefore, damages to nuclear DNA are not considered as a major cause of cryoinjury in chicken semen. However, we propose that comet assay is suggested as a useful tool in multiparametric sperm assessment to investigate sperm sensibility to cryopreservation in chicken.