Production of Gas in Rumen Fermentations and Stable Mass Formation from Alfalfa Fiber and Pectic Substances

A series of laboratory experiments was carried out to help identify some of the chemical characteristics of alfalfa that were considered a part of the complex causing stable foam formation in the rumens of cattle. Gas production in in vitro rumen fermentations, and stable foam formation after mechanically blending with water, were determined, using various fractions of alfalfa and other substances. The results show that the plant substances responsible for the initial rapid gas production obtained with green alfalfa were closely associated with the fiber fraction, but were removed after digesting in vitro 4-10 hr. with rumen microorganisms or by extracting 12 hr. with hot water. Purified pectin, crude pectins, glucose, and galactose increased gas production when added to washed alfalfa fiber. Hydrolyzed pectin produced the most marked effect, yielding 2.25 times as much gas as the washed fiber. Concurrent hydrolysis of macerated alfalfa with pectinase during digestion also increased gas production.