Effects of nonenzymatic and enzymatic antioxidants in cryopreserved canine semen extended with docosahexaenoic acid

Polyunsaturated fatty acids (PUFAs), such as docosahexaenoic acid (DHA), could be an alternative to improve cryopreserved canine sperm by increasing membrane fluidity. However, PUFAs also increase sperm susceptibility to lipid peroxidation. Supplementation of the extender with DHA and antioxidants could be an alternative. We evaluated supplementation of antioxidants (vitamin E and catalase) of cryopreserved canine semen extended with DHA. In Experiment 1, ejaculates from 8 dogs were divided into 4 aliquots, with increasing concentrations of DHA in the extender (0, 1, 5, and 10 µM) and cryopreserved. Sperm motility increased in 5 µM DHA and it was used for Experiment 2; ejaculates from 8 dogs were divided into 4 groups: control (5 µM DHA), vitamin E + DHA, catalase + DHA, and vitamin E + catalase + DHA. Samples were evaluated for susceptibility to lipid peroxidation, sperm kinetics, mitochondrial function, DNA integrity, and plasma and acrosomal membrane integrity. Vitamin E + DHA group had beneficial effects on the characteristics of sperm kinetics whereas the catalase + DHA group was harmful to sperm mitochondria. Vitamin E + catalase + DHA group decreased oxidative stress and damage to the plasma membrane and had low mitochondrial membrane activity. Addition of DHA + vitamin E in canine semen extender improved sperm quality after cryopreservation.