Comparison of FACSCount AF system, Improved Neubauer hemocytometer, Corning 254 photometer, SpermVision, UltiMate and NucleoCounter SP-100 for determination of sperm concentration of boar semen.

Current research aims at reducing the number of sperm per insemination dose thereby making measurement of sperm concentration in raw semen and the production of uniform insemination doses much more crucial. The present study evaluated the determination of sperm concentration using FACSCount AF System (FACS), Improved Neubauer hemocytometer (HEMO), Corning 254 photometer (Photo C254), SpermVision CASA System (SpermVision), UltiMate CASA System (UltiMate) and NucleoCounter SP-100 (SP-100). The instruments were evaluated with respect to repeatability and to establishing the regression curve towards both HEMO and FACS. Repeatability for the instruments was 2.7, 7.1, 10.4, 8.1, 5.4 and 3.1% for FACS, HEMO, Photo C254, SpermVision, UltiMate and SP-100, respectively. Correlation between instruments was highest between FACS and SP-100. This was made possible due to the high repeatability for both instruments. The agreement between the instruments and HEMO as the gold standard was lower than expected as the largest difference in estimation of concentration was -25 to +50%. The largest percentage difference was observed for measurements of dilute semen. It was clear that percentage difference between instruments depended on sperm concentration. In comparison to the gold standard, agreement was highest between SpermVision and HEMO for dilute semen, but for concentrated semen, agreement was highest between SP-100 and HEMO. However, the agreement between HEMO and all other instruments was not as good as expected. The reason may lie within the presence of agglutinated sperm, preventing proper HEMO counts.