"The Army Veterinary Service has three major missions: (1) Inspection of food used by the military including its processing and the sanitary inspections of the establishments producing it; (2) provision of a comprehensive animal service; and (3) conduct of veterinary laboratory services concerned with food and various types of research. All of these missions assist the Army Medical Service to protect the health of human beings and animals.
"The veterinary animal service, as might have been expected, was the major activity of the Veterinary Corps in World War I. Great numbers of horses and mules were used, in a ratio of one animal to every three men. The outcome of major campaigns frequently depended upon the size and efficiency of animal transport. In World War II, which was a war of men and machines, the ratio was 1 animal to every 134 men. Obviously, in such a war, food inspection was the principal task of the Army Veterinary Service, and medical service for animals was of somewhat lesser importance. In World War I, an estimated 20 percent of Veterinary Corps personnel were utilized to inspect the Army's subsistence supply. In World War II, between 90 and 95 percent were used for this purpose...." (Foreward).
Digital text available from U.S. Army Medical Department Office of Medical History at this link.