The Effect of Added Fat on the Digestion of Cellulose and Protein by Ovine Rumen Microorganisms

Abstract

The addition of corn oil (10–170 mg.) to 1 gram of dry matter containing 50 percent cellulose in the artificial rumen inoculated with ovine rumen organisms significantly reduced cellulose digestion (40–94%). Thirty-two or 64 grams of corn oil added to a basal cottonseed hulls and casein ration significantly reduced cellulose digestion and lowered protein digestion in sheep. Rumen ingesta had a putrid odor, a turbid color and a lowered volatile fatty acid content. The total number of bacteria present was not reduced, but there was a decrease in the number of small rods and an increase in small cocci when fat was present. Aerobacter aerogenes was isolated from the rumen contents of sheep fed 64 grams of corn oil. Thirty-two or 64 grams of lard added to the basal ration also decreased cellulose digestion. The depressing effects of added corn oil or lard were partially overcome by addition of alfalfa ash.