Acetic acid is not involved in enhanced intestinal protein synthesis by the presence of the gut microflora in chickens.

1. The present study was conducted to clarify whether or not acetic acid was responsible for enhanced intestinal protein synthesis by the gut microflora in chickens. 2. Conventional and germ-free chicks were fed a practical experimental diet supplemented with or without powdered distilled acetic acid for 10 days from 8 to 18 days of age. At the end of the experimental period, intestinal protein synthesis was measured by injecting a large dose of L-[4-3H]phenylalanine through a wing vein. 3. The results showed that the responses of fractional synthesis rate and protein: DNA ratio to acetic acid supplementation in the jejuno-ileum and caecum were opposite to those observed by the presence of the gut microflora. 4. It was conducted, therefore, that acetic acid was not involved in enhanced intestinal protein synthesis by the presence of the gut microflora in chickens.