COMPUTERIZED ANALYSIS OF SPERM MOTION - EFFECTS OF GLYCEROL CONCENTRATION ON THE CRYOPRESERVATION OF EQUINE SPERMATOZOA

An experiment was conducted to examine the effects of glycerol added t o a glucose-sucrose-dried skim milk freezing extender (B4) at 0, 1, 2, or 4% for cryopreservation of equine spermatozoa. Two ejaculates from each of three stallions were used in the study. Following cryopreserv ation and storage in liquid nitrogen for at least 30 days, the semen w as thawed and subsequently diluted to approximately 33 x 10(6) sperm/m l in the freezing extender minus glycerol and egg yolk at 30 degrees C . It was then incubated for 1 h at room temperature prior to evaluatio n, Each semen sample was evaluated for the percentage of motile sperm (M, %), the percentage progressively motile sperm (PM, %), velocity (V , mu/sec), progressive velocity (PV, mu/sec), linearity (L, %) and lat eral head displacement (LHD, mu) using computer-aided sperm analysis ( CASA). The data were statistically analyzed and the optimal glycerol c oncentration was determined for each parameter. For three of the param eters (M, PM and LHD), the 2% level of glycerol was selected by the st atistical analysis as optimal (P<.05), while for the parameters (V and PV), the 1% level of glycerol was selected as optimal (P<.05). Lastly , linearity was highest in sperm frozen without glycerol and decreased (P<.05) with glycerol addition. Therefore, based on the results of th e motion characteristics examined in the present study, we suggest tha t a 2% level of glycerol appears to provide maximum cryoprotection wit h a minimum potential for detrimental effects in stallion semen frozen as described herein.