Cholesterol/phospholipid ratio in sperm of several domestic species does not directly predict sperm fitness for cryopreservation

摘要

Sperm cryopreservation is used for preservation and diffusion of genetic diversity and genetic progress. One approach to improve cryopreservation is to identify and control the cellular parameters responsible for intrinsic sperm fitness for cryopreservation. The aim of this study was to determine if a relationship exists between sperm cholesterol/phospholipid molar ratio (CHO/PL) and sperm fitness for cryopreservation. CHO/PL in goat and boar semen were respectively 0.281+/-0.048 (n=112) and 0.375+/-0.043 (n=47). CHO/PL of washed stallion spermatozoa was 0.541+/-0.072 (n=17). In stallion spermatozoa and goat semen, CHO/PL and sperm motility after thawing were negatively correlated, although the significance of this relation fluctuated between ejaculates (stallion) and between months of collection (goat). In boar, mobility parameters after thawing were not related to CHO/PL, but a positive correlation was noted between CHO/PL and the percentage of spermatozoa alive and normal 120 min after thawing. No relationship was found between blood plasma cholesterol (goat: 1160 nmol.mL(-1) +/-186; boar: 1410 nmol.mL(-1) +/-200) or seminal plasma cholesterol (boar sperm rich fractions 104 nmol.mL(-1) +/-52) and sperm CHO/PL. To conclude, sperm CHO/PL is not a direct indicator of sperm fitness for cryopreservation. However, as supported by the observed correlation, it could not be ruled out that CHO/PL is involved in the cryopreservation success.