SUMMARY
The objective of this study was to compare between propolis (as natural antibiotic) and synthetic antibiotics on sperm survivability and protection against bacterial contamination of extended ram semen. Ethanolic extract of propolis was prepared by dissolving either powder or glue (10 grams/100 ml ethanol) for 24 hrs. then stored in dark at 4oC. In this study, seven mature rams were used for semen collection using artificial vagina. Tris-glucose-egg yolk (TGE) extender was prepared. Samples of pooled semen were diluted at extension rate 1: 10 (semen: extender). Then, extended semen was divided into 6 portions, served as T1, T2, T3, T4, T5 and T6 each contained 0.2 ml of Pen-Strep (T1), Alamycin LA (T2), Vetrocin (T3) and propolis ethanolic extract as powder (T4) or glue (T5), respectively. The 6th portion (T6) was served as control without any antibiotic addition. The characteristics of spermatozoa such as motility, livability and normality and bacteriological procedure for T1, T2, T3, T4, T5 and T6 were assayed during incubation at 37°C from 0 to 3 hours. The results indicated that extended ram semen in groups T1, T3, T4 and T5 exhibited higher (P < 0.05) percentages of motility, livability and normality than T2 and T6 during incubation. However, T1, T4 and T5 appeared not successful (P>0.05) to suppress bacterial contamination. However, T4 and T5 showed more effectiveness in controlling bacterial growth after 3 hrs of incubation. Moreover, maximum (P<0.05) inhibitory bacterial zones were observed in T4 and T5 than other experimental treatments.
It could be conclude that either propolis powder or glue supplementation at 0.2% of extender had a potential effect among the experimental antibiotics tested. In addition, propolis can be used to restrain the bacterial infection and improve semen quality. However, testing more different levels of propolis in a fertility trial would be applied in future studies.