Comparative Antibiotic and Probiotic Effects on Antimicrobial Sensitivity of Escherichia coli Isolates and Performance of Broiler Chickens

The study evaluated the growth performance, haematology, serum biochemistry, intestinal microbial count, and antimicrobial resistance profile of Escherichia coli(E. coli) from broiler chicks fed diets supplemented with antibiotics (neomycin, and oxytetracycline), and probiotic (Saccharomyces cerevisiae). One hundred and twenty Abor acre broiler chicks randomly alloted to four treatment groups (30 birds/group;10 birds/replicate) were used in the 49 days study. Group one (G 1, control) were fed basal diet while G 2, 3, and 4 received basal diet containing S. cerevisiae(0.80g/kg; 108cfu/g), neomycin (0.50g/kg) and oxytetracycline (0.30g/kg), respectively. Results showed significant treatment effects on body weight, feed intake, linear body values, some haematological indices, intestinal, caecal and combined caecal and intestinal bacteria counts, diameter of E. coliinhibition zone, and mortality. Body weight andfeed intake were significantly higher in the supplemented groups. Intestinal bacterial count was highest in neomycin and control groups (5.29 ± 0.01 and 5.22 ± 0.02 Log10cfu/ml, respectively) while S. cerevisiaeand neomycin groups yielded thehighestcaecal, and combined caecal and intestinal bacterial counts. EimeriaOocyst count did not differ significantly between groups. Escherichia colifrom antibiotic fed groups had reduced sensitivity or were resistant to the antibiotics. It was concluded that subtherapeutic use of antibiotics as growth promoters in broiler chickens caused the development of antibiotic resistance, and therefore, should be avoided.