Effect of extenders on sperm mitochondrial membrane, plasma membrane and sperm kinetics during liquid storage of canine semen at 5 °C

The objective of this study was to evaluate the effect of addition of egg yolk (EY) or soy lecithin (SL) based extenders on dog sperm parameters during 10 days storage at 5 °C. Four ejaculates of pooled semen from three Mongrel dogs were divided into three aliquots and extended to a final concentration of 200 million sperm/mL using following non-commercial extenders: egg yolk extender (EYE) group - semen + 20% Tris-EYE; soy lecithin (SL) group 1 - semen + SL extender with 0.04% SL; SL group 2 - semen + SL extender 0.4% SL. The extended semen samples were stored at 5 °C and were evaluated for sperm mitochondrial membrane potential (MMP), plasma membrane integrity (%PMI) and computer assisted sperm analyzer (CASA) sperm motility parameters on days 0, 1, 2, 3, 4, 7 and 10. The extender, days of storage and extender × days of storage affected the MMP, %PMI and CASA sperm motility parameters (P < 0.05). The addition of 0.4% SL extender reduced the speed of deterioration of sperm parameters evaluated in this study compared to EY and 0.04% SL extenders (P < 0.05). In conclusion, the addition of 0.4% SL extender enhanced sperm preservation based on the variables evaluated in the present study compared to EYE and 0.04% SL extenders and plausibly preserves sperm quality longer.