Effect of Dietary Penicillin on Blood Composition and Œstrogen-induced Oviduct Growth in the Folic-Acid Deficient Chick

Abstract

STUDIES designed to elucidate the processes responsible for the growth-promoting effects of dietary antibiotics have shown that the growth-rate of chicks and rats deficient in individual vitamins is increased by addition of an antibiotic. Growth responses to antibiotics on adequate diets have also been shown to be accompanied by increases in blood and liver concentrations of certain vitamins¹. It has been pointed out by Coates et al.² that such increases may be non-specific to antibiotic treatment and may merely accompany a growth acceleration. Common et al.³ demonstrated an increase in the blood levels of calcium and riboflavin in œstrogen-treated pullets as a result of adding aureomycin to an adequate diet. On the basis of experiments by Hertz et al.⁴ such an increase could be attributed to an increase in dietary availability of these nutrients. In view of these remarks concerning the difficulty in interpreting such increases in blood- and tissue- levels of a particular metabolite resulting from the inclusion of an antibiotic which also causes a growth stimulation, the two criteria of folic acid availability chosen in the experiment reported here were end-organ response to œstrogen and hæmoglobin-level in the blood. A short period of œstrogen treatment affects both blood composition and oviduct growth-rate, and the latter has been shown to be specifically reduced by folic-acid deficiency⁵.