The effect of varying concentrations of chicken plasma egg yolk and glycerol on the viability of canine sperm following short and long-term preservation

Background: Plasma egg yolk (PEY), due to simple preparation and easier access, could be a suitable alternative to raw egg yolk for preserving canine semen. Aims: The present study investigated suitable concentrations of PEY and glycerol for preservation of canine semen. Methods: Semen was collected by digital manipulation (seven replicates from four dogs). Following initial raw semen evaluation, the semen was diluted in a tris-based extender supplemented with varying concentrations of chicken PEY (0, 20, and 40% v/v) and glycerol (3%; v/v). After cooling the specimen to 4°C within 1 h, the specimens were diluted with an equal volume of freezing extender consisting of similar concentrations of chicken PEY and 0 and 7% glycerol to reach the final glycerol concentration of 1.5 and 5% for short-term storage of canine semen. Samples with different concentrations of PEY and 5% glycerol were frozen. The sperm viability parameters including total motility, progressive forward motility, plasma membrane integrity, and live percentage of sperm were assessed following short and long-term storage. Results: Sperm viability parameters of semen extended in an extender supplemented with 20 or 40% chicken PEY with either 1.5 or 5% glycerol remained superior until 72 h after semen collection compared to the specimen that did not receive any PEY (P 0.05). Post-thaw sperm viability was also greater in samples extended in extender supplemented with either 20 or 40% PEY compared to 0% PEY. Conclusion: Tris-based extender supplemented with either 20% chicken PEY could be suitable for short and long-term preservation of canine semen.