Effects of probiotics on in vitro ruminal profile and population of some cellulolytic bacteria

The aim of this study was to evaluate the effects of probiotics on ruminal pH, ammonia nitrogen, production of short chain fatty acids (SCFA) and number of Ruminococcus albus and Ruminococcus flavefaciens. The probiotics blend was tested in vitro for 48 h incubation using "Hohenheim Futterwert Test" (HFT). There was no interaction effect of the treatment and incubation time on the ruminal pH and ammonia-nitrogen concentration. A supplemental probiotics blend tended to increase the total SCFA concentration in comparison to the non-supplemented control fermenter fluids (P> 0.05). There was a significant interaction effect of the treatment groups and incubation time on butyrate (P=0.042), valerate (P=0.045) and isovalerate (P= 0.028) concentrations. Total protozoa and total bacteria numbers were higher in probiotics supplemented fluid than in non-supplemented control fluid (P<0.001 and P<0.01, respectively). Dietary supplementation of a probiotics blend to the fermenters did not influence (P>0.05) the number of copies of R. albus. However, the population of R. flavafaciens was lower (P<0.01) in the probiotic supplemented group as compared with the non-supplemented control group. Our results showed that the probiotics blend might modulate both microbial metabolic activity and the population of ruminal microorganisms.