Could tannins be the right dietary alternative for replacing antibiotics as growth promoters in broiler chicken production? A comprehensive microbiota shift assessment in a commercial farm

Abstract

One of the main global issues in animal production is the antimicrobial use (AMU) as prophylactic additives in diet. Despite the availability of a variety of antibiotic alternative additives, their use is not widespread. In this study, we analyzed samples from a trial conducted on a commercial farm, evaluating cecal and litter microbiota with the inclusion of antibiotics or tannins (as AMU-free alternative) in the diet. We observed differential modulation depending on the additive used. Specifically, tannins treatment led to an increased Firmicutes/Bacteroidetes ratio, due to a rise in Clostridiales order, which is associated with improved gut health and better energy efficiency in birds. Poultry litter microbiota contained typical gastrointestinal tract bacteria, along with pathogenic and environmental species. This information becomes relevant for litter reuse in poultry sheds, acting as an inoculum for new birds in the next cycle, determining their microbiota; or when litter is used as organic fertilizer, and these bacteria potentially spread to the environment. This study highlights the potential of tannins as a promising AMU-free alternative in food-producing animals, contributing to new productive paradigms that consider human health, animal welfare, environmental impact, and production efficiency.

Keywords: Broiler chicken; Commercial farm; Growth promoter; Microbiota; Tannin.

Fig. 1

PCoA of weighted (A) and unweighted (B) UniFrac distances between cecal and litter samples.

Fig. 2

Bacterial communities’ composition at phylum (A) and family (B) level. CON: control treatment; BAC: Treatment with Bacitracin; TAN: Treatment with Tannins. L: Litter samples; C: cecal samples. 1, 2, and 3 represent the replicates corresponding to each treatment. Statistically differences (P < 0.05) found between cecal and litter samples were indicated with an asterisk (*).

Fig. 3

PCoA based on weighted (a) and unweighted (b) UniFrac distances from cecal samples. Each color represents a treatment: CON: control treatment, BAC: Bacitracin treatment, TAN: Tannin treatment.

Fig. 4

Microbial communities’ composition of cecal samples at the phylum level (A). CON: control treatment, BAC: treatment with Bacitracin supplementation, TAN: treatment with Tannin supplementation. 1, 2, and 3 represent the three replicates performed per treatment. Statistically differences (P < 0.05) found between treatments were indicated with an asterisk (*). (B) Firmicutes/Bacteroidetes ratio in CON, BAC, and TAN treatment.

Fig. 5

Microbial communities’ composition of the cecal samples at family (A) and genera (B) level. CON: control treatment, BAC: treatment with Bacitracin, TAN: Treatment with Tannins. 1, 2, and 3 represent the replicates corresponding to each treatment. Statistically differences (P < 0.05) found between treatments were indicated with an asterisk (*).

Fig. 6

Bacterial communities’ composition of litter samples at the phylum level. The structure of the bacterial community for the three replicates of the different treatments is shown: CON: control, BAC: bacitracin, TAN: tannins.

Fig. 7

Microbial communities’ composition of litter evaluated at family (A) and genera (B) levels. The top 20 most abundant taxa for the three replicates per treatment are shown: CON: control, BAC: bacitracin, TAN: tannins.