The Effect of Feeding Aureomycin on the Bacterial Content of Chick Feces

The action of antibiotics in stimulating chick growth, while not clearly understood, is generally believed to be effected through changes in the intestinal microflora of the chick. The following experiments were undertaken to obtain information regarding the bacterial microflora in the feces of chicks fed various diets with and without the addition of aureomycin. In each test the chicks were reared in electrically heated battery brooders with wire screen floors where they had free access to feed and water. The various diets fed are briefly described in Table 1. When fecal collections were made wax paper was placed over the dropping trays. The feces were transferred immediately after voiding to sterile flasks. After a 1–2 hour collection period the sample of feces from each experimental lot was thoroughly mixed and a 0.5 gm. sample taken for serial dilutions. Suitable dilutions were plated according to the customary pourplate procedure. Three . . .