Mineral Requirement of Rumen Microorganisms for Cellulose Digestion In Vitro

A washed suspension, artificial rumen technique was utilized in a series of studies to determine the optimum concentrations of sulfur, magnesium, calcium, copper, cobalt, iron, and zinc for in vitro, cellulose digestion by rumen microorganisms. Consideration was also given to toxic levels of these elements. Limited studies were made of the influence of boron, phosphorus, and the carbonate ion. Of the minerals studied, sulfur, magnesium, and calcium were found to be the inorganic nutrients most likely to be deficient in a prepared fermentation medium. Additions of maganese, iron, copper, cobalt, zinc, and boron to the fermentation medium did not result in increased cellulose digestion. Extremely low lewels of copper,1 cobalt, zinc, and boron depressed cellulose digestion.