This study aimed to evaluate the effect of propolis supplementation on semen extender of Egyptian buffalo semen to improve sperm characteristics and antioxidant capacity of sperm medium after cryopreservation. Tris-egg yolk extender with different levels (0, 4, 8, 12, and 14 mg/ml) of propolis ethanolic extract (PEE) were used. Semen was collected once/week for 20 weeks from five buffalo bulls aged 3.5–5 years. The collected semen was pooled and distributed into five equal fractions, each fraction was diluted with Tris-extender at each level of PEE (PEE0, PEE1, PEE2, PEE3, and PEE4). Semen was gradually diluted at 37 °C with each extender at a rate of 1: 10, equilibrated for 4 hours at 4 °C, packaged in French straws, and frozen in liquid nitrogen at -196 °C. Evaluation of semen was achieved pre-freezing in equilibrated semen and post-thawing in semen thawed in a water bath at 37oC for 30 seconds. Results showed that PEE2 showed the highest (P < 0.05) positive impact on improving progressive motility, livability, abnormality, and acrosome integrity of spermatozoa in pre-freezing and post-thaw semen. All PEE-extenders increased (P < 0.05) viable sperm percentage, and level of total antioxidant capacity and superoxide dismutase activity, and decreased percentage of apoptosis, early apoptosis, necrosis, and malondialdehyde level; most favorable results were recorded with PEE2. The foregoing results indicated that supplementation of Tris-semen extender with propolis ethanolic extender at a level of 8 mg/ml increased the functional activity of spermatozoa, decreased sperm apoptosis, and necrosis, and improved the antioxidant status of sperm medium in cryopreserved semen of Egyptian buffaloes.
Keywords | Egyptian buffalo, Propolis extract, Cryopreservation, Semen variables, Lipid peroxidation