Experimental infection with Escherichia coli in broilers: Impacts of the disease and benefits of preventive consumption of a stimulator of homeopathic immunity

Abstract

Colibacillosis is a disease caused by Escherichia coli that manifests itself when there are homeostatic imbalances or in the context of increased exposure, in which case the organism displays opportunistic behavior. To control this problem in poultry, antibiotics are used in the feed, because E. coli is component of the intestinal microbiota of birds. However, because of the changing dietary habits of the human population that seeks out healthier foods without antimicrobial residues, there have been many studies of alternatives to replace conventional antimicrobials as performance enhancers. Thus, the objective of the present study was to determine whether daily consumption of a homeopathic product (immune stimulator) by broilers stimulates immune responses and thereby minimizes the negative effects of experimental E. coli infection. We used 320 1-day-old Cobb 500 chicks, distributed in two groups with eight repetitions each, and 20 birds per repetition: control (CG) and homeopathy (HG). HG birds consumed doses of 0.02 mL/bird/day (1–7 d) via water, 0.01 ml/bird (8–21 d), 0.02 ml/bird (22–28 d), 0.01 mL/bird (29–35 d), and 0.02 mL/bird (35–45 d), as recommended by the manufacturer. At day 22 of the birds' life, the two groups were divided into four subgroups, with four repetitions per subgroup. On day 22, birds in CG1 and HG1 groups were infected intraperitoneally with 0.5 mL of inoculum containing 1.0 × 108 CFU of E. coli/mL. During the experimental period, data were collected for analysis of performance. On days 21 and 45 of age, we collected blood and feces. During the first 21 days of the experiment, we found that birds that consumed the immunostimulator had lower neutrophil counts and higher levels of globulins, however without significant difference between groups in terms of performance. Uninfected birds that consumed the homeopathic product in the water had less feed conversion (HG2) between days 1–35 and 1 to 45 compared to the other treatments. Mortality was higher in groups experimentally infected with E. coli (HG1 and CG1) from 22 to 35 days of life. There were greater numbers of lymphocytes in the HG2 group on day 45 than in CG1 and CG2; while numbers of neutrophils were lower at 42 days in birds of groups HG1 and HG2 than in CG1. Lower total bacterial counts, total coliforms and E. coli were observed in the feces of birds in the HG2 group compared to the other groups. Taken together, these findings suggest that inclusion of homeopathic product in the water of broilers had positive effects on the modulation of the immune response and on feed conversion in birds not challenged with E. coli. But the preventive protocol used in this study was not able to minimize the negative effects caused by the experimental E. coli intraperitoneal infection in broilers, featuring a substantial infectious challenge.