Evaluation of the use of propolis as a replacement for synthetic antibiotics in boar semen extenders

Abstract

Antibiotics are of great importance in semen extenders to ensure long shelf life of spermatozoa and control bacterial contamination. These bacteria compete with the sperms for nutrients and produce toxic substances that decrease sperm viability. Synthetic antibiotics that are usually used in these extenders, these however lead to antibiotic resistance which is a global rising problem. The aim of this study was to use propolis which is a natural antibiotic as a replacement for synthetic antibiotics while maintain the viability of the sperms. According to various studies, propolis has shown various biological functions, one of which is antimicrobial property. This is due to the fact that propolis contains more than 300 compounds belonging to polyphenols, terpenoids, steroids, sugars, amino acids among others. In this study, semen samples were divided into 12 parts. Four (4) of the 12 parts were extended using extender containing propolis which was the natural antibiotic. The other 4 parts were extended using extender containing ciprofloxacin which was the synthetic antibiotic while the remaining parts were extended using extender containing no antibiotic. 100µl of the samples were then inoculated in wells on nutrient agar plates with E. coli as the model organism. The agar plates were then incubated for 24 hours observe susceptibility. The semen parameters were analyzed before and after extension for the different extenders to establish viability after extending. The results demonstrated that propolis did not effectively prevent bacterial contamination therefore it cannot be used as a replacement for synthetic antibiotics in semen extenders. Propolis however maintained viability of the sperms as it is seen that there was no statistical significance in the motility and live-dead ratio values before and after extending the semen using extenders containing propolis. further studies need to be carried out on propolis as an energy source and antioxidant due to the maintenance of sperm viability.