Volatile fatty acid utilization by the liver slices and the rumen epithelium of the young calves

Abstract

Twenty Holstein calves were fed on limited amount of whole milk, green forage or orchard grass hay and grain. They were sacrificed at 1, 4, 8, 13 and 23 weeks of age to determine the development of the uptake of VFA by the liver slices and the rumen epithelium. Five hundred mg of the liver slices or 2g of the rumen epitheliun were incubated at 38°C for 3hrs in Krebs-Ringer-phosphate buffered at pH 7.2 in an atmosphere of oxygen. Two hundred μ-moles of acetate, propionate, butyrate, or an equimolar mixture of these three acids were added to medium.
1. In the liver slices, the utilization of acetate most increased with age, compared with that of propionate and butyrate. The utilization of acetate by the liver slices from the calves at 1 or 4 weeks of age was lower than at 8 weeks or more weeks of age, and was markedly increased from 4 to 8 weeks of age. Propionate and butyrate were utilized by the liver slices, but the utilization of them showed no marked change due to age.
2. In the rumen epithelium, the butyrate utilization most increased due to age. The utilization of butyrate in the newborn calves was extremely low, and increased until it reached adult level by 8 weeks of age. The utilization of acetate and propionate did not increase with the increase of age.