AbstractArtificial saliva (4 litres/day) was infused into the rumen of sheep fed a semi‐purified diet at hourly intervals. Dilution rate and the efficiency of synthesis of microbial protein in vivo were increased. The pattern of rumen fermentation was altered; the molar proportion of propionic acid decreased (32–20%) and acetic acid increased (58–66%) with infusion, and there was an increased flow of total amino acids into the duodenum.