Role of Propolis Ethanolic Extract as an Antioxidant Supplement in Tris-Extender to Enhance Semen Quality of Egyptian Buffaloes during Cryopreservation

Abstract

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.