Investigation of the effects of syringic acid supplemented to Tris semen diluent on ram semen freezability

To the best of our knowledge, no research has been conducted to test the effects of syringic acid (SA) on ram semen freezing within the scope of natural antioxidants added to semen extenders. Therefore, this study had two main objectives. First, to test whether adding SA to ram semen freezing extender has a protective effect and contributes positively to sperm kinetic, plasma and acrosome integrity, mitochondrial membrane potential, lipid peroxidation, oxidant and antioxidant and DNA damage pa- rameters after thawing. Second, it was to determine at what concentration the SA supplemented to the extender could be applied by in vitro studies by preserving the fertilization ability of frozen semen at the highest level. In the study, six individuals of Sonmez rams were used. The semen was collected from the rams using an artifi- cial vagina and pooled. The pooled semen was divided into five different groups and extended with 0, 0.5, 1, 2 and 4 mM SA (control C, SA0.5, SA1, SA2 and SA4, respec- tively). After dilution, the semen samples were kept at 4 degrees C for 3 h, then loaded into 0.25 mL straws and frozen in liquid nitrogen vapour. The SA1 and SA2 groups were higher plasma membrane and acrosome integrity (PMAI), high mitochondrial mem- brane potential (HMMP), plasma membrane integrity and motility compared to other groups (p < .05). It was observed that SA supplemented to the Tris extender signifi- cantly reduced DNA damage, and the lowest values were obtained especially in the SA1 and SA2 treatments (p < .05). Also, lowest MDA level was determined at the SA1 and this was statistically significant compared to SA4 and C (p < .05). In conclusion, it was revealed that SA added to Tris semen extender at 1 and 2 mM treatment doses increased progressive and total motility and preserved PMAI, plasma membrane in- tegrity, HMMP and DNA integrity.