Metabolic evaluation of cooled equine spermatozoa

Microscopy has been used in the routine evaluation of sperm metabolism. Nevertheless, it has limited capacity to preview male fertility. As calorimetry may be used to evaluate directly the metabolic activity of a biological system, the aim of this study was to use microcalorimetry as an additive method for sperm metabolism evaluation of cooled equine semen. Two ejaculates of four stallions were collected and motility, viability (eosin 3%) and membrane functional integrity (hyposmotic swelling test) of spermatozoa were evaluated. Sperm samples were processed following different protocols and the metabolism of these samples was accessed by calorimetry. Centrifugation is part of some of these processing protocols and although this procedure has been deleterious for sperm viability and plasma membrane integrity, no decrease in sperm motility was observed. Microcalorimetry was capable of detecting the positive effect of re-suspending the sperm pellet with Kenney extender. Thus, the use of microcalorimetry offered additional information for equine sperm metabolism evaluation and was efficient in detecting important information from sperm cell metabolism.