Bacteriophage cocktail supplementation to prevent Escherichia coli in native chickens in Tra Vinh province of Vietnam

The bacteriophage cocktail (BC) was therapeutically used as an effective alternative to antibiotics for the control of colibacillosis in local chickens. The present study aimed to determine the alternative biocontrol effectiveness of BC against Escherichia coli (E. coli) in one-day-old broiler chicks in Tra Vinh province. Herein, the experiment design showed that BC was given at 109 CFU/mL, whereas E. coli was given at 107,7 CFU/mL. A total of 120 chicks were randomly divided into three treatments in Experiment 1, including (i) negative control (NC) (gavaged with PBS); (ii) positive control (PC) (challenged with E. coli); and (iii) E1 (challenged with E. coli and gavaged with BC at 1, 3, 7, 14, and 21 days of age). In Experiment 2, 160 chicks were randomly assigned to one of four treatment groups consisting of (i) NC (gavaged with PBS); (ii) PC (challenged with E. coli); (iii) E2-1 (challenged with E. coli and gavaged with BC at 2 hours post-challenge, 3, 4, 5, 6, 7, 14, and 21 days of chick age); and (iv) E2-2 (challenged with E. coli and gavaged with antibiotic at the same time point as E2-1). According to the results of the present study, the mortality rate in the experiment groups using BC in both Experiments (E1 and E2-1) were significantly lower than those in the PC group. Besides, the results indicated that E. coli bacteria were only found in the heart, liver, and spleen of experimental chicks at 9 days of age in both Experiments. The bacterial density was lower than those in the PC group in both Experiments. Notably, there were no noticeable changes in BC and antibiotic groups. The findings of this study exhibited the promising effects of BC for controlling colibacillosis infections in native poultry.