The addition of antioxidants to semen cryopreservation extenders has been employed for combating oxidative damage. This work aimed to evaluate the addition of carotenoid canthaxanthin to a cryopreservation extender of ram semen. Three breeder rams were used and, after semen collection, with 48-hour intervals between collection, the samples were included in the pool formation (n = 6). The experimental groups comprised 0 (control), 0.1, 1, 10, and 25 μM of canthaxanthin. After thawing (37°C/30 s) and incubation at 37°C for 2 hours, semen aliquots from each group were evaluated for sperm kinetics (CASA), the integrity of the plasma and acrosomal membranes (iPAM), intracellular reactive oxygen species (ROS) production, and lipid peroxidation (LPO) by flow cytometry associated with the image. The control group and canthaxanthin 1 μM after incubation at 37°C for 2 hours showed increases of curvilinear velocity and amplitude of lateral head displacement with decreases of linearity, straightness, and wobble (p < 0.05), which were not observed for the canthaxanthin 10 and 25 μM. The supplementation of a Tris-egg yolk extender with canthaxanthin had no effect on the iPAM, intracellular ROS production in viable spermatozoa, or LPO. In conclusion, supplementation with 10 and 25 μM of canthaxanthin in a Tris-egg yolk extender used for ram semen cryopreservation is able to protect ovine sperm from kinetic changes after incubation at 37°C for 2 hours post-thawing.
Keywords: canthaxanthin; cryopreservation; oxidative stress/injury; ram spermatozoa.