Effects of Ultrasonic Treatment of Chicken Yolk on the Cryopreservation of Boar Semen

Ultrasonic treatment significantly improves the emulsifying properties of chicken egg yolk. This advancement not only provides a novel approach for enhancing the physical stability of yolk-based cryodiluents, but also holds promising implications for optimizing the cryopreservation efficacy of boar semen. This study evaluated the effects of conventional egg yolk (CON) and ultrasonicated egg yolk (UT-CEY) on boar semen cryopreservation. Semen samples were cryopreserved using standard straw freezing methods, with post-thaw sperm quality parameters assessed. Results demonstrated that UT-CEY significantly reduced yolk particle size (<i>p</i> < 0.01), improved emulsion stability (<i>p</i> < 0.01), and decreased creaming index (<i>p</i> < 0.05). Additionally, UT-CEY enhanced total motility, progressive motility, straight-line velocity (VSL), and plasma membrane integrity (<i>p</i> < 0.01), along with acrosome integrity (<i>p</i> < 0.05) compared to CON. Furthermore, catalase (CAT) and superoxide dismutase (SOD) activities were elevated in UT-CEY (<i>p</i> < 0.01), while reactive oxygen species (ROS) fluorescence intensity showed no significant difference (<i>p</i> >0.05). Gene expression analysis revealed upregulated <i>Bcl-2</i>, <i>CAT</i> (<i>p</i> < 0.01), and <i>SOD₂</i> (<i>p</i> < 0.05) in UT-CEY. In conclusion, ultrasonicated egg yolk diluent improves boar semen cryopreservation efficiency and post-thaw sperm quality.