The Effect of Increasing Concentrations of Terramycin on the Growth and Intestinal Microflora of Chicks

NUMEROUS reports have been published concerning the beneficial effects of antibiotics on poultry and swine. Smith and Robinson (1945) found that streptomycin administered orally produced a marked reduction in the coliform bacteria of the intestine of mice, and Moore et al. (1946) in a study of the use of antibacterial agents found that the inclusion of streptomycin in the diet resulted also in a significant response in growth of chicks. Stokstad et al. (1949) were the first to report that fermentation liquors of Streptomyces aureofaciens were capable of producing growth increments in chicks greater than those obtained with vitamin B12 alone. Subsequently, Matterson and Singsen (1951), working with chicks, and Carpenter (1951) with swine, observed that aureomycin, terramycin, streptomycin, penicillin, and other antibiotics stimulated the growth rates of their experimental subjects. Various theories have been discussed by Groschke (1950), Groschke and Evans (1950), and Biely and March (1951) to account . . .