Comparative study on effects of soy lecithin and egg yolk-based extenders on canine semen preservation at refrigeration temperature

The objective of the study was to evaluate the effect of addition of Tris soy lecithin (TSL) and Tris egg yolk- based (TEY) extenders on canine seminal attributes during 7 days storage at 5°C. Semen was manually collected from fifteen apparently healthy male dogs, which then underwent semen evaluation. Only semen sample with spermatozoa motility >80% and spermatozoa concentration >200×106 spermatozoa/mL were used in the present study. After initial evaluation, sperm-rich fractions were divided into two equal parts and extended with 20% TEY and 1% TSL extenders at 1:4 dilution, then stored at a refrigeration temperature of 5°C for 7 days. Chilled semen samples were assessed for pH, motility, viability, abnormality, and plasma membrane integrity for a week on daily basis. DNA integrity was assessed on days 0, 1, 3, and 5 of storage. Significant differences were observed in all seminal attributes except DNA integrity between fresh and extended semen. The pH of the semen did not differ significantly between the extenders up to day 6, indicating almost equal buffering capacity of the extenders. A significant difference in sperm motility, viability, morphological abnormality, and plasma membrane integrity was observed between the extenders from storage days 4, 3, 1, and 5, respectively. No significant difference in sperm DNA integrity was observed between the extenders. In conclusion, while both extenders were equally effective in preserving sperm DNA integrity, Tris egg yolk extender outperformed Tris soy lecithin extender in all other seminal attributes assessed in this study.