Usefulness of a portable flow cytometer for sperm concentration and viability measurements of rainbow trout spermatozoa

The aim of this study was to test the usefulness of a portable flow cytometer in relation to the measurement of sperm concentration and viability in rainbow trout (n - 12). This method was compared with the currently used methods, including the spectrophotometric method, computer-aided fluorescence microscopy and a haemocytometer. The mean concentration obtained using a spectrophotometer (9.86 +/- 3.69 x 10(9) spermatozoa ml(-1)) and a fluorescence microscope (10.46 +/- 3.60 x 10(9) spermatozoa ml(-1)) was significantly lower than that obtained with a flow cytometer (12.35 +/- 3.88 x 10(9) spermatozoa ml(-1)) and a haemocytometer (11.73 +/- 4.78 x 10(9) spermatozoa ml(-1)). Significant regressions (P < 0.0001) between sperm concentration obtained by using a flow cytometer, a spectrophotometer (y = 0.93 x-1.64; r(2) = 0.95), a fluorescence microscope (y - 0.90 x -0.69; r(2) - 0.94) and a haemocytometer (y - 1.16 x -2.57; r(2) = 0.87) were found. The sperm viability determinations obtained using a flow cytometer were significantly higher (97.00 +/- 0.99%) than the values obtained by using fluorescence microscopy (86.22 +/- 1.16%). However, a significant regression was found between these two viability measurements (r(2) = 0.26, P < 0.05). To the best of our knowledge, this is the first study related to the usefulness of a portable flow cytometer in vertebrate sperm analysis. The flow cytometer provides fast measurement of sperm concentration and viability. The advantage of a compact flow cytometer is the ability to incorporate the examination of other sperm functions related to apoptosis, mitochondrial potential, oxidative stress and DNA fragmentation in future fish reproductive studies. Statement of relevance Study relevant to sperm concentration, viability monitoring. (C) 2015 Elsevier B.V. All rights reserved.