Influence of cooling temperature in sperm subpopulations of domestic cats

The objective of this study was to identify and compare domestic feline sperm subpopulations, chilled at −1 °C for 24 and 48 h, as well as to analyze the sperm frequency in different subpopulations. Ten adult cats were used. Sperm collection was performed using electroejaculation (EEJ). Spermatic kinetics were evaluated using a computerized system at three moments: fresh, 24 and 48 h after refrigeration. The ejaculates were divided into a group refrigerated at −1 °C (n = 5,) and a group refrigerated at 4 °C (n = 5),. A total of 1560 spermatozoa were analyzed individually, and the sperm subpopulations were identified using multivariate statistics. Three spermatic subpopulations were defined using prior analysis of the hierarchical dendrogram. A principal components analysis (PCA) identified the existence of three groups with higher iterations at the three moments: PC1 (VAP, VCL, VSL, ALH, SVI), PC2 (STR, LIN, WOB and SMI) and PC3 (BCF). Subpopulation 1, after 48 h of refrigeration at −1 °C, and subpopulation 3, after 24 h of refrigeration at 4 °C, maintained their sperm quality, which allowed us to characterize the groups of spermatozoa that were resistant to cryopreservation. The present study identified three well defined ejaculate spermatozoa subpopulations, with proportional distributions between the groups and two refrigeration resistant subpopulations.