Excretion Rates of Antibiotics in Milk of Sheep and Their Effect on Yogurt Production

Abstract

Excretion rates in milk of sodium penicillin G, streptopenicillin, oxytetracycline, and chlortetracycline given to sheep by intramuscular injection or intramammary infusion were studied. When given by intramuscular injection, penicillin G and streptopenicillin were excreted in milk for 24 h, oxytetracycline for 38 h, and chlortetracycline for 72 h. The corresponding times following intramammary infusion were 72 to 86 h, 72 to 86 h, 96 to 110 h, and 110 to 120 h. Concentrations in milk of penicillin, streptopenicillin, and oxytetracycline given by intramuscular injection made it unsuitable for yogurt production for 24 h. Chlortetracycline, although excreted in milk longer, did not affect yogurt production. When antibiotics were given by intramammary infusion, they were excreted in milk in concentrations harmful for yogurt production for 72, 72, 96, and 116 h. © 1982, American Dairy Science Association. All rights reserved.