Foaming Properties of Alfalfa and Their Relationship to Bloat

Abstract

The foaming properties of alfalfa were found to be associated primarily with the leaves and were influenced by the method used to obtain an extract of the plant material for foam measurements. The stability of the foam depended on the temperature and pH of the macerating medium, with an optimum at about 20° C. and pH 5.5. Freezing and lyophilizing of extracts were the only methods found for preserving the foaming characteristics of a forage sample. Freezing the sample before maceration increased the foam stability up to 50%. Alfalfa samples from plots grazed by cattle were tested for foam stabilities under standardized conditions. A significant correlation coefficient of 0.56 between bloat and the foam stability values was observed. Existence of a foam inhibitor (s), which is extractable from alfalfa, has been demonstrated. The results suggest that the plant contains a complex system of foaming agents, foam inhibitors, and foam stabilizers, and that its bloat-producing potential may be the net effect of a delicate balance of these groups of substances.