Semen analysis with computer assisted sperm analysis (CASA) systems requires specialized counting chambers and specific pre-dilution protocols for the semen sample. Disposable counting chambers can vary considerably with regards to the height of the measuring gap, optical quality of the glass and sperm friendliness of the glue between slide and cover slip. Sample preparation and chamber loading protocols are error-prone due to pipetting flaws and difficulties in correctly loading the capillary gap. The eFlow system for AndroVision® uses a fully automatic fluid management system to load a reusable counting chamber with a pre-diluted sample, allowing for a user-friendly, robust and highly automated sample preparation and chamber loading.
Three different sample volumes (5ml, 6ml, 7ml) for loading the reusable counting chamber of the eFlow system were compared for each of 7 pre-diluted (1+6) native ejaculates from different boars. This pre-dilution rate corresponds to the dilution rate used under field conditions. For each of the sample volumes per boar, double measurements of the semen concentration were performed with the eFlow system and AndroVision®. The means of the double measurement were tested for influence of the sample volume with analysis of variance (ANOVA) considering the boar/ejaculate as error. In addition, the semen concentration of each of the pre-diluted boar ejaculates was determined with a NucleoCounter (NC, SP-100TM Chemometec, Allerød, Denmark) as a reference method for the measurement of semen concentration. For goodness of measurement accordance evaluation for each of the three sample volumes, the Concordance Correlation Coefficient (CCC, Lin, Biometrics 45; 255, 1989) was calculated.
ANOVA did not reveal statistically significant differences in semen concentration measurements depending on sample volume used to fill the eFlow chamber (p=0.088). However, as the statistical power is low (1-β = 0.1), a possible effect of the sample volume cannot be excluded, albeit a non-significant difference. The comparison of the estimated means of each sample volume (contrast analysis) showed a tendency for lower valences in semen concentration results with a sample volume of 5 mL compared to 6 mL sample (-0.91 Mio. sperm/mL, p=0.074). The CCC for the 5, 6 and 7mL sample volumes and NC measurements were 0.999, 0.989 and 0.983, respectively.