Volatile Fatty Acids in Portal Blood of Sheep

Abstract

VOLATILE fatty acids—chiefly acetic, propionic and butyric acids—are formed as a result of the fermentation processes in the rumen of sheep and are absorbed through its wall. With the purpose of investigating the concentration of these acids and other constituents in the portal blood during a digestion cycle, that is, the 12-hour period after feeding, a slightly modified London canula was fixed adjacent to the main trunk of the portal vein of two sheep¹, which had previously been provided with a rumen canula and an exteriorized loop of the carotid artery. The feed, which consisted of 125 gm. chopped hay, 200 gm. linseed meal and 15 gm. blood meal, was given every 12 hours², and all was consumed within an hour. The total amount of volatile fatty acids in rumen liquor was determined by steam distillation, and separated into acetic, propionic and butyric plus higher acids using the chromatographic technique of Elsden³. For determination of total volatile acids in blood a modification of the method of McClendon⁴ was adopted. Blood-sugar estimations were carried out according to Somogyi⁵ with an accuracy of ±0·11 m.mol. per litre.