Post-thaw quality of donkey (Equus asinus) spermatozoa exposed to different concentrations of curcumin with respect to oxidative status and nitric oxide.

Donkey sperm cryopreservation is a critical tool for preserving male fertility. But freezing and thawing could adversely affect sperm quality. There is limited information available regarding curcumin supplementation with different doses in sperm cryopreservation in donkeys. This study aimed to determine the alterations in post-thaw motility, viability, DNA integrity, acrosome integrity, and sperm kinematic parameters in relation to enzymatic leakage and nitric oxide levels in response to the addition of different doses of curcumin to the extender in male donkeys. Ejaculates were collected after semen collection from six male donkeys and then pooled. Samples were diluted with Tris-egg yolk glycerol extender. After centrifugation, pellet was diluted with an extender and divided into the five main groups containing curcumin at different concentrations, as C0 (control; 0 mM), C1 (0.125 mM), C2 (0.25 mM), C3 (0.5 mM), and C4 (0.75 mM). Semen quality was measured after thawing via CASA kinematic assessment and enzymatic leakage, such as alanine and aspartate aminotransferase levels (ALT and AST). Malondialdehyde (MDA), nitric oxide (NO), and catalase (CAT) levels were measured. Results revealed a significant elevation in motility, viability, DNA integrity, acrosome integrity, and CASA parameters with a linearity and straightness of sperm when curcumin was added at a concentration of 0.5 mM compared to others. AST, ALT, MDA, and NO levels were significantly declined at 0.5 mM of curcumin, with an elevation of CAT levels. The addition of curcumin improved sperm motility, kinematic parameters, viability, acrosome integrity, DNA integrity, antioxidant activity (CAT), and reduced both oxidative stress-related markers (MDA and NO), and cellular leakage markers (ALT and AST). Greatest improvements were observed at a curcumin concentration of 0.5 mM with a Tris-egg yolk glycerol extender of frozen-thawed donkey spermatozoa.