Effect of rosemary (Rosmarinus officinalis) extracts and glutathione antioxidants on bull semen quality after cryopreservation

The present study determined the effects of the addition of rosemary extract (ROM), glutathione (GSH), and their combination (ROM + GSH) to freezing extender on the quality of bull semen after cryopreservation. Before cryoperservation, the samples were diluted in a tris-egg yolk (TEY) extender containing 5 mM GSH (treatment I), 5 or 10 g L-1 ROM (treatments II and III), and ROM with GSH (5 mM GSH with 5 or 10 g L-1 of ROM) (treatments IV and V). An extender containing no antioxidants (non-ROM/GSH-treated) served as control group. Kinematic parameters were evaluated by means of a computer-assisted semen analysis (CASA). The viability and membrane integrity of the sperm were assessed using eosin-nigrosin stain and the hypo-osmotic swelling test (HOST) at 0 and 2 h after freeze-thawing. Lipooxidative parameters, superoxide dismutase, and glutathione peroxidase (GPx) activity were assessed after thawing. Treatment III showed positive effects for total motility (TM) (p <0.01), average path velocity (VAP) (p <0.001), viability (p <0.01) and HOST (p <0.01); however, lipid peroxidation (LPO) decreased (p <0.05) and GPx activity increased (p <0.05) immediately after thawing compared to the control. The TM (p <0.01), VAP (p <0.01), viability (p <0.01), HOST (p <0.01) decreased in LPO (p <0.01) and GPx activity (p <0.05) for treatment V and the viability and GPx activity (p <0.05) for treatment I were significantly higher than for the control group at 2 h after thawing. It was concluded that the inclusion of ROM and its combination with GSH improves the post-thaw quality of bull semen.