INTEREST OF ANTIBIOTICS IN FROZEN BOVINE SEMEN - CONTROL OF MYCOPLASMAS AND CAMPYLOBACTERS

Two studies have been conducted to control opportunistic pathogen bact eria in frozen bovine semen. The first one was reported by Shin et al. (1988) and was based on (a) an experimental in vitro contamination of raw bull semen with various types of bacteria, (b) adding several ant ibiotics, alone or in combination with different concentrations. The s econd experiment, performed in our laboratory was designed to compare from 240 split ejaculates the effect of adding concentrated solutions of antibiotics to the raw semen vs control (ie addition of antibiotics in the extender). The combination of gentamicin (500 ug / ml)-tylosin (100 ug / ml)-linco-spectin (300 / 600 ug / ml) was found to be the m ost effective on the strains of bacteria tested. The addition of a con centrated solution of antibiotics to the raw semen was not found here to be of any advantage on the numbers of CFU. Furthermore, such a prot ocol contributed to significantly decrease the percentage of motile sp ermatozoa. In conclusion, opportunistic pathogens such as those here s tudied may be kept under control with the appropriate antibiotics and with no deleterious effect on semen parameters provided that they are added at the adequate concentrations in the diluents used for semen cr yopreservation.