Effect of chamber characteristics, loading and analysis time on motility and kinetic variables analysed with the CASA-mot system in goat sperm

•Drop-filling chambers demonstrated higher values than capillarity-filling chambers for sperm motility.•A gradual drop of motility and kinetic parameters was shown as time after loading increased in the droplet-loaded chambers.•Capillarity-loaded chambers showed lower sperm total motility in the central fields.

Several factors unrelated to the semen samples could be influencing in the sperm motility analysis. The aim of the present research was to study the effect of four chambers with different characteristics, namely; slide-coverslip, Spermtrack, ISAS D4C10, and ISAS D4C20 on the sperm motility. The filling procedure (drop or capillarity) and analysis time (0, 120 and 240 s), depth of chamber (10 or 20 μm) and field on motility variables were analysed by use of the CASA-mot system in goat sperm. Use of the drop-filling chambers resulted in greater values than capillarity-filling chambers for all sperm motility and kinetic variables, except for LIN (64.5% compared with 56.3% of motility for drop- and capillarity-filling chambers respectively, P < 0.05). There were no significant differences in total sperm motility between different chamber depths, however, use of the 20 μm-chambers resulted in greater sperm progressive motility rate, VSL and LIN, and less VCL and VAP than chambers with a lesser depth. There was less sperm motility and lesser values for kinetic variables as time that elapsed increased between sample loading and sperm evaluation. For sperm motility, use of droplet-loaded chambers resulted in similar values of MOT in all microscopic fields, but sperm motility assessed in capillarity-loaded chambers was less in the central fields than in the outermost microscopic fields. For goats, it is recommended that sperm motility be analysed using the CASA-mot system with a drop-loaded chamber within 2 min after filling the chamber.