Theory Involving Propionate and Vitamin B12 in the Low-Milk Fat Syndrome

Abstract

A new theory to explain the low-milk fat syndrome of cows fed high-grain, low-fiber diets is proposed. This theory involves alteration of propionate metabolism caused by increased rumen propionate production coupled with a deficiency of vitamin B~2. Attempts to correct the low-milk fat problem were through administrations of vitamin B12 to cows with depressed milk-fat. Daily intramuscular or intravenous injections of cyanocobalamin, cyanocobalamin plus folic acid, B-complex vitamins, and coenzyme B12 (6 to 18 mg of each compound) failed to increase milk fat percentage. Fifty milligrams of hydroxocobalamin injected intramuscularly increased milk fat yield approximately 200 g per day.