Volcano plots (A) CON vs. PROB, (B) CON vs. SYNB, and (C) PROB vs. SYNB, showing the differential ruminal metabolites in beef steers fed diets supplemented with S. cerevisiae-based direct-fed microbial products. FC ≥ 1.2, p-value ≤ 0.05 (in red)—significantly increased; FC ≤ 0.83, p-value ≤ 0.05 (in blue)—significantly reduced relative to CON. CON = control; PROB = a blend of S. cerevisiae, Enterococcus lactis, Bacillus subtilis, Enterococcus faecium, and L. casei, and their fermentation products fed at 19 g/steer/day (PMI, Arden Hills, MN); SYNB = a blend of live S. cerevisiae and the fermentation products of S. cerevisiae, Enterococcus lactis, Bacillus licheniformis, and Bacillus subtilis fed at 28 g/steer/day (PMI, Arden Hills, MN).