Metabolism of [14C]propionic acid in broiler chicks

Broiler chicks were given 4 or 120 mumol propionic[1-14C] acid by gavage to determine its chemical fate and distribution of radiolabel among organs and tissues [foregut (crop, gizzard, and proventriculus), intestine (small and large), ceca, liver, and serum]. At 15 and 60 min postgavage, most of the extractable radiolabel remaining in the chicks was found in the foregut. Significantly higher percentages of the administered radiolabel were detected at 15 min in the serum and liver extracts of chicks given 120 mumol of propionic acid than in chicks given only 4 mumol. After 15 min, 41 and 30%, respectively, of the total radiolabel administered was accounted for in extracts of the digestive tract and tissues of chicks given 4 or 120 mumol of [14C]propionic acid. Only about 12% of the administered radiolabel was extracted from body compartments at 60 min postgavage from chicks given 4 mumol of propionic acid. Collection of respired [14C]CO2 during a 3-h postgavage period indicated that orally administered propionic acid is largely (about 75%) used as an energy source or is metabolized and assimilated into body components. The present studies indicate that little if any dietary propionic acid reaches the lower digestive tract and the ceca.