EFFECT OF MADURAMICIN AND MONENSIN ON SURVIVAL OF LACTOBACILLUS-SALIVARIUS 51R ADMINISTERED IN THE CROP AND CECA OF YOUNG CHICKENS

A rifampicin-resistant Lactobacillus salivarius 51R was administered o rally to newly hatched broiler chickens. The resistance to rifampicin enabled us to differentiate the organism administered from indigenous strains. One day after inoculation, Lactobacillus salivarius 51R domin ated among lactobacilli in the crop and caeca of an inoculated chicken s, even in those ones receiving maduramicin and monensin at 5 and 100 mg,per kg of feed mixture, respectively. Coliform counts in both crop and caeca of inoculated chickens were significantly lowered on the fir st day after treatment. Also, counts of the crop enterococci were decr eased in inoculated chickens. Rifampicin-resistant lactobacilli were s till present in high numbers in the crop and caecal contents of inocul ated chickens sampled 5 days after inoculation. Differences in counts of total lactobacilli, coliform bacteria, and enterococci were mostly nonsignificant in these samples. Our results demonstrate that (i) bact erial counts in the chicken gut were influenced by probiotic Lactobaci llus administration, and (ii) chicken lactobacilli are resistant to io nophore coccidiostats under ill vivo conditions.