Review of antimicrobial growth promoting agents available.

Abstract

Some antibiotics and synthetic chemotherapeutics of quinoxaline and nitrofuran groups have a practical value among the agents stimulating weight gain and feeding efficiency of farm animals commonly referred to as nutritive, ergotropic agents or growth promoters. In order to avoid undersirable results for human beings they should not be applied for therapeutic purposes; they should not bring about any resistance in microorganisms and should not carry the risk of lowering the therapeutic activity of antibiotics and chemotherapeutics; they should not be absorbed from the alimentary tract and should be rapidly eliminated from the animal body; they should not cause allergic reactions in animals or humans and should act chiefly against Gram-positive microorganisms. The following nutritive antibiotics are described: flavophospholipol (producing an ergotropic effect not only in young animals but also in ruminants; having an antiplasmidic action and restoring the sensitivity of some resistant bacteria towards antibiotics), avoparcin (also active in ruminants), virginiamycin, zinc bacitracin and bacitracin methylene disalicylate, grisin (having a broad spectrum of antibacterial activity, an antimycotic action; stimulating fertilisation and phagocytosis), vitamycin-A (active at low concentrations of retinol in the feed), lambdamycin, noziheptide, efrotomycin. Due consideration is given to some chemotherapeutics such as nitrovin, carbadox (having a broad spectrum an antimicrobial action; giving residues for a long period in the body of pigs), olaquindox (with a broad spectrum, active more on Gram-negative microorganisms, applied mostly as a therapeutic agent), cyadox (with broad spectrum and lower toxicity). Polyether (ionophorous) antibiotics with an anticoccidial action and with an ergotropic activity in ruminants (increasing the molar percent of propionic acid and decreasing that of acetic and butyric acid; suppressing the production of carbon dioxide and methane; enhancing the blood sugar content) are mentioned: monensin sodium, lasalocid sodium, salinomycin sodium, lonomycin and narazin.