Absorption from the Omasum and Subsequent Metabolism of Butyrate and Acetate

Labeled sodium salts of butyric or acetic acids were injected into the exteriorized omasunI of four calves, with the objective of further characterizing absorption from that organ. Changes in, and subsequent use of, the absorbed butyrate also were studied. Organic acid levels and distribution of C ~' activity were deternfined in blood drawn simultaneously from the onmsal vein and carotid artery at four times during 15 rain following injection. The animals then were sacrificed and similar deternfinations made on stomachs' ingesta. Butyrate-C ~' rapidly disappeared from the omasum. There was evidence of limited conversion of butyrate to other volatile fatty acids, both in the ingesta of the omasum and in the blood. The major portion of the C ~' from butyrate appeared in the blood as betahydroxybutyrate (BHBA) in close association with blood lactate. BHBA was separated from lactate by first preparing hydroxamate derivatives, then employing chromatographic-autoradiographic procedures. Most of the C 1' appeared in BttBA, regardless of whether the label had been on the first or third carbon of injected butyrate. Considerable radioactivity was found in blood bicarbonates following butyrate-l-C ~* injection. Acetate was absorbed and appeared in the blood.