Evaluation of cockerel sperm viability and motility by a novel enzyme based cell viability assay.

1. The results of spermatozoa assessment by the WST-8 (2-[2-methoxy-4-nitrophenyl]-3-[4-nitrophenyl]-5-[2,4-disulfophenyl]-2H-tetrazolium, monosodium salt) assay, flow cytometry (FC) or computer-assisted sperm analysis (CASA) were compared.2. Different live/killed ratios of cockerel semen were serially diluted to 120, 60, and 30x10(6) cells/ml, and each sample was analysed by (1) WST-8 assay at 0, 10, 20, 30, 40, 50, 60min, (2) viability with FC, and (3) motility with CASA.3. The WST-8 reduction rate was closely correlated with spermatozoa viability and motility. The optimal semen concentration for the WST-8 assay was 120x10(6) cells/ml, and the standard curves for spermatozoa viability and motility predictions, respectively, were y(viability60)=162.8x + 104.96 (R-2=0.9594) after 60min of incubation and y(motility40)=225.09x + 96.299 (R-2=0.8475) after 40min of incubation.4. It was concluded that the WST-8 assay is useful for the practical evaluation of cockerel spermatozoa viability and motility. Compared to FC and CASA, the WST-8 assay does not require expensive and complex instrumentation in the lab. Furthermore, one well of the WST-8 reaction can be used to predict spermatozoa viability and motility at the same time, which all lead it to be efficient and economical for semen quality assessment.