Determination of optimal glucose concentration for microcalorimetric metabolic evaluation of equine spermatozoa

The heat conduction microcalorimeter can be used to evaluate the metabolic rates of the sperm cell. Tw o ejaculates of four stallions were cooled to +5 0 C and checked for sperm motility (bright field micr oscopy), viability (eosin 3%), functional membrane integrity (hyposmotic swelling test), and heat production (microcalorimetry). Gluc ose and sperm cell concentrations were determined in order to measure the heat outputs resulting from sperm me tabolism. Sperm viability, membrane integrity and sperm motil ity did not differ among the different glucose conc entrations tested. Nevertheless, the highest heat output detec ted by the microcalorimeter was obtained with 6 mM glucose and 10 8 spermatozoa/mL. Since conduction microcalorimetry offered additional information on equine sperm metabolism, it could be used as a method to study e quine semen preservation.