Antibiotics in Dairy Cattle Nutrition. I. The Effect of an Aureomycin Product (Aurofac) on the Growth and Well-Being of Young Dairy Calves

noted that an animal protein factor supplement derived from cultures of Streptomyces aureofaciens would produce a growth response in chicks which was greater than the maximum response obtainable with vitamin B12. The same year Cunha et al. (4) obtained similar results when a residual fermentation product remaining from the manufacture of pure aureomycin was fed to pigs. In early 1950, Stokstad and Jukes (19) found that pure crystalline aureomycin would produce a growth response in chicks similar to that obtained with products from aureomycin fermentation, thus demonstrating the role of antibiotics as dietary growth stimulators. Later, in 1950, several workers reported (reviewed by Stokstad, 18) that aureomycin and several other antibiotics were beneficial in the rations of non-ruminant animals, such as chickens, turkeys and pigs. At that time it was conjectured that antibiotics possibly would interfere with the nutrition of ruminant animals by destroying necessary rumen microorganisms. Since the newborn calf behaves like a non-ruminant animal in the digestion of food, investigations were initiated to determine whether or not aureomycin added to the diet would stimulate growth in young calves.