The Effect of propolis solutions as extender supplementation on boar semen parameters during liquid storage for 72 hours

Abstract

Propolis, also known as bee glue, is a natural resinous substance used by bees to defend the hive, has many biological components and is characterized by anti-inflammatory, anticancer, antioxidant, antibiotic, antifungal, wound-healing properties and can also improve male and female fertility rates. The aim of the study was to define the effect of different concentrations of aqueous and ethanolic extracts of propolis on boar semen viability, motility and pH changes during semen storage for 72 hours at 16 ºC temperature storage. Eleven ejaculates were collected from breeding boars and diluted with long-term extender. After receiving the semen doses in the laboratory the initial tests of semen pH, sperm motility, viability and morphology were performed. After initial studies, each dose was divided into five samples and supplemented with different concentrations of propolis: control – without supplementation, 5% and 10% ethanolic (5EP and 10EP), 5% and 10% aqueous (5AP and 10AP) solutions) at a final concentration of 50 x 0⁶ sperm/mL. One hour after addition of the propolis extracts, the semen motility, viability and pH tests were performed. After keeping semen samples in the refrigeration thermostat at 16 °C for 72 hours laboratory tests were repeated. A total of 110 sperm viability, motility and pH tests were performed. Storage of semen samples for 72 hours at 16 °C temperature reduced the viability and motility in all samples but the highest semen viability remained in the samples with 5AP and 10AP solutions, 61.64 ± 6.38% and 60.82 ± 4.9% respectively. In the control group the semen viability mean after 72 hours was 49.18 ± 7.16% and the viability mean difference between the control group and 5AP was 12.45% (P < 0.05). The highest sperm motility mean after 72 hours storage was found in the samples with aqueous propolis solutions, 82.61 ± 6.60% 5AP and 84.06 ± 4.74% 10AP respectively. The smallest motility mean differences after 1 hour and 72 hours of storage was also observed in the samples with aqueous extracts of propolis (P > 0.05). The highest pH mean was found in 10AP samples (7.33) and the pH mean of these samples after 72 hours changed the least, by 0.16% (P ≥ 0.05). The largest change in pH means, by 0.58%, was found in control samples (P < 0.05). The study showed that adding aqueous extracts of propolis at 5% and 10% concentrations to boar semen can improve sperm motility, viability and semen pH during liquid storage at 16 ºC for 72 hours, meanwhile no improvements in semen parameters were observed with the use of 5% and 10% ethanolic propolis extracts.