Probiotic Composition Influences the Major Rumen Microbial Shifts and Fermentation Profile as Evaluated Using Quantitative PCR and In Vitro RUSITEC System

Complex microbial interactions govern rumen functionality. We report use of quantitative PCR (qPCR) and rumen simulation technique to study the effect of probiotics, PF 1 and PF 2 on Prevotella ruminicola, Fibrobacter succinogenes, Ruminococcus flavefaciens, Selenomonas ruminantium, and Streptococcus bovis followed by volatile fatty acid and fiber reduction. Probiotic PF 2 up-regulated R. flavefaciens by 60.54%, down-regulated F. succinogenes, and doubled the concentration of propionic acid from 111 +/- 16 mg/L to 251 +/- 12.58 mg/L (P<0.05). PF 2 dosage improved the fiber digestibility; with fiber reduction from 37.42 +/- 0.5 to 6 +/- 0.05% w/w (P<0.05). Principal component analysis revealed a direct relationship between probiotic, days, and number of copies of targeted microbes (P<0.05). It demonstrated a positive correlation between P. ruminicola and S. bovis with butyric and propionic acids. In contrast, a strong negative correlation seen established between butyric and propionic acids with F. succinogenes and fiber content. We report that, rumen microbial shifts possess unique pattern upon probiotic interventions, revealing distinct fiber digestibility. To our knowledge; this is the first report of rumen bacterial quantification upon probiotic intervention using qPCR.