Metabolic Role of Rumen Mucosa in Absorption of Butyrate

A rumen fistula, portal vein catheter, and exteriorized carotid artery or femoral arterial catheter were established in two calves to study the extent of ketone formation during the passage of butyrate through the rumen wall. Addition of a 0.02 m 3-C 14 -butyrate solution to the rumen of the calves resulted in a rapid rise in both the arterial and portal blood ketones, although the level was consistently higher in the portal blood. Most of the activity (67.7-97.7%) present in the blood samples collected from the two calves was in the β -hydroxybutyrate fraction. The portal ketones reached maximum levels 30min after the butyrate addition to the rumen with both calves, but were markedly higher in a seven-month-old calf (10.8mg %) than in a two-month-old calf (3.0 mg%).