THE PRODUCTION OF ORGANIC ACIDS IN THE PIG: II. THE EFFECT OF DIET ON THE LEVELS OF VOLATILE FATTY ACIDS AND LACTIC ACID IN SECTIONS OF THE ALIMENTARY TRACT

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Abstract
Two experiments were conducted to measure volatile fatty acids and lactic acid in the alimentary tract of pigs. The animals had been fed either a cellulose-, bran- or dried whey-supplemented diet before slaughter.The cellulose-supplemented diet generally gave a lower total organic acid content than did the control diet, for each section of the tract examined. A high concentration and large quantity of organic acid characterized the colon of the pig.In the second experiment, where the control diet was supplemented with either bran or dried whey, formic acid was found only in the stomach and small intestine of each pig. Lactic acid in the large intestine was found less often in the bran-fed pigs than it was in the pigs fed the other two diets.The digesta of the small intestine gave the lowest (P < 0.01) total concentration (meq./100 ml.) of organic acid. The concentration of acid in the caecum of the control pigs was nearly twice that reported for the caecum of cattle.The proportion of lactic acid decreased progressively as the digesta passed along the tract, the differences being highly significant (P < 0.01) between the upper sections (stomach and small intestine) and lower sections (caecum and colon). There was a tendency for the bran-fed pigs to have a greater proportion of acetic acid in the digesta than the controls. Acetic, propionic and butyric acids were found in the caecum of the bran-fed pigs in the proportions of 60, 32 and 7.5 per cent, respectively. The type of diet and the locality of the digesta affected significantly the proportion of acids found in the alimentary tract.The largest quantity of organic acid (gm.) was found in the stomach and slightly less in the proximal portion of the colon. The total quantity of organic acid present in the alimentary tract at the time of examination was calculated to be 45, 60 and 49 grams for the control, whey- and the bran-fed pigs respectively.