Determining the In Vivo Efficacy of Plant-Based and Probiotic-Based Antibiotic Alternatives against Mixed Infection with Salmonella enterica and Escherichia coli in Domestic Chickens

Abstract

Restrictions on the use of antimicrobial compounds have led to a surge of interest in alternative solutions, such as natural, plant-based compounds. In our study, we investigated the efficacy of three feed supplements containing different additives, namely, probiotics (<i>Lactobacillus</i> spp., "Test substance A"), turmeric (<i>Curcuma longa</i> L., "Test substance B"), and fenugreek (<i>Trigonella foenum graecum</i>, "Test substance C"). In the experiment, we tested 180 birds of the Bábolna Tetra-SL laying hybrid breed that were infected with <i>Salmonella enteritidis</i> strains. The birds were randomly divided into six groups: three groups treated with the different additives, a negative control group, a positive control group, and an antibiotic-treated group using enrofloxacin. We examined the maturation and the time course of shedding of <i>Salmonella</i>; at the end of rearing, pathological and histopathological examinations were performed. When <i>Salmonella</i> was isolated from the cloacal swab samples, the enrofloxacin-treated group had a high number of animals shedding <i>Salmonella</i> by day 9, which was like the group treated with test material C. The greatest reduction in <i>Salmonella</i> shedding was observed in the groups treated with test materials A and B. In terms of pathological parameters, villus length and crypt depth were significantly better in the group treated with test material C compared to the positive and negative controls, and when comparing the body weight of the tested animals, the group treated with test material B had a significantly larger absorption surface area compared to the positive control group. Overall, the supplement with test material C proved to be the most effective. In the future, it is worthwhile to investigate the combination of the tested active substances for their possible synergistic effects and to perform a dose-response study to select the optimal dosage.