Comparative Efficacy of Enrofloxacin and Oxytetracycline by Different Administration Methods in Broilers after Experimental Infection with Avian Pathogenic Escherichia coli

Abstract

The aims of this study were to compare the efficacy of 2 kinds of antibiotics that are commonly used in the Thai broiler industry and to determine the optimal times of drug administration. One hundred and sixty, 21-day-old broilers were divided into eight groups. Chickens in groups 1, 2 and 3 were challenged with avian pathogenic E. coli (APEC) and received oxytetracycline for the first 3 days after infection via oral, drinking water within 2 h and drinking water throughout the day, respectively. The chickens in groups 4, 5 and 6 were challenged with APEC and received enrofloxacin for the first 3 days after infection via oral, drinking water within 2 h and drinking water throughout the day, respectively. The chickens in group 7 and 8 served as positive and negative control groups. Enrofloxacin treated chickens showed better results in feed conversion ratio, mortality, gross pathology and bacterial isolation than those treated with oxytetracycline (p<0.05). Infections of chickens with APEC can be treated with the enrofloxacin. Oral administration provided a better protection than drinking water within 2 h and drinking water throughout the day, respectively.