Effects of Various Incubation Conditions on Functional Parameters of Stallion Spermatozoa

Abstract The objective of our study was to determine the effect of 5% of CO2 atmosphere and time of sample dilution on results of in vitro analysis of stallion semen. Frozen-thawed semen from 14 stallions was incubated either in incubator or in a water bath, diluted prior to analysis or immediatelly after thawing. The following qualitative parameters were assessed after thawing (T0) and after 30 min (T30): motility in 3 sperm subpopulations (slow, medium, fast) defined by cluster analysis of parameters obtained by Computer Assisted Sperm Analysis, viability, acrosome and mitochondrial integrity. The slow subpopulation was only significantly reduced in diluted samples in CO2 atmosphere at T0 (P < 0.05). In diluted samples the incubation time significantly affected distribution of fast, slow, and medium subpopulations in CO2 and CO2 free atmosphere (P < 0.05), respectively. Viability, acrosome and mitochondrial integrity were not affected by CO2 atmosphere (P > 0.05), however acrosome (at T0) and mitochondrial integrity (at T30) were significantly higher in CO2 atmosphere in non-diluted and diluted samples (P < 0.05), respectively. The results of the in vitro analysis of stallion semen were rather similar regardless of the atmosphere or dilution time.