Effect of dietary herbal extracts on broiler growth performance and intestinal microbiota

Abstract

This trial examined the effects of dietary use of an oregano, garlic, camelina and crithmum extract either encapsulated in cyclodextrin or in an aqueous form, on growth performance and on intestinal microflora ecosystem. Control Group A (CL) was fed basal diets based on maize and soybean meal with a trial duration of 35 days. Bacterial community diversity and structure in the ileum and caecum samples after slaughter was investigated through 16S rRNA gene high-throughput amplicon sequencing on the V3-V4 hypervariable region, generating over 30,000 reads/sample. Fimicutes, Proteobacteria and Bacteroidota were the most representative phyla in all diets in both caecum and ileum samples. Intestinal microflora was also dominated by Actinobacteriota, whereas this phylum was less representative in caecum. Alpha-diversity indices highlighted higher species richness and diversity in caecum versus ileum samples, as well as in treatments with the aqueous extract of herbal mixture but only in caecum. Taking into consideration that ileum and caecum samples appeared to consist of heterogenous bacterial assemblages, the beta diversity of the bacterial communities was higher between groups rather than within groups for both tissues. As for LefSe analysis, the most abundant bacterial taxa serving as potential biomarkers in the aqua-herbal diet belong to the class of Campylobacteria (ileum) or Clostridia (caecum), whereas in the cyclodextrin-herbal diet, to the families of Lactobacillaceae (ileum) and Methanobacteriaceae (caecum). In conclusion, dietary mixtures of herbal extracts improved protein and lipid oxidation in meat and increased beneficial lactic acid bacteria in caecum.