Studies on the production of volatile fatty acids from grass by rumen liquor in an artificial rumen: I. The volatile acid production from fresh grass

Abstract

1. A study has been made over two growing seasons of the volatile fatty acid production from ley grass obtained from a single area of one field, under the action of rumen liquorin vitro.2. The acida estimated were acetic, propionic, butyric, valeric and caproic. On only one occasion did the last named appear in measurable amount.3. The main acid produced in early stages of the year is acetic acid, but as the season advances propionic acid becomes the acid of major production.4. In parallel cellulose runs it was found that propionic acid was invariably produced in greater amount than any other acid.5. An attempt has been made to eliminate, by using cellulose as a standard, the effects of using different rumen liquor samples.6. The dried samples, corresponding to the fresh material, were invariably found to yield acetic acid in greater proportion than propionic acid. The average percentages of acids obtained from the dried grass were similar to those found by other workers. It is suggested that the variations between the fresh and dried grass results are due to changes in carbohydrate content resultant upon storage of the latter.