FEEDING A BIOACTIVE EXTRACT FROM OLEA EUROPAEA TO BROILER CHICKENS EXERTS A POSITIVE IMMUNOREGULATORY EFFECT WITHOUT MAJOR EFFECTS ON GUT MICROBIOT

The present study examined the effects of bioactive compounds from a standardized Olea europaea extract (OE) on gut microbiota composition and immune response in broiler chickens. A total of 3 hundred and 6 1-dold broiler chickens (Ross 308) were randomly allocated in floor pens (6 pens / treatment, with 17 birds/pen). From 1 to 21 d of age animals were fed with a common non-medicated starter diet based on wheat and soybean meal, and from 22 to 42 d of age with their 3 respective experimental diets: a basal diet with no additives (C) and the same diet with either 100 ppm of monensin (M) or 1000 ppm of OE (Lucta S.A., Spain). At the end of trial, 2 birds per pen (n = 12) were randomly selected to collect blood for measuring circulating concentration of cytokines and glycoprotein and cecal contents for assessing microbiome profile, which was done via DNA extraction and PCR amplification on the V1-V2 regions of 16S rRNA gen. Additionally, ileal mucosa was sampled to analyze gene expression of ASBT, ChREBP, SREBP1, FABP2, FABP6, Claudin1, TGF-β4, Bu-1, TLR4 and 2β, CD3γδ, IL-2, IL-6, IL8, and IFN-g markers. Analysis of variance was performed with animal as the experimental unit and diet as fixed effect. A mixed-model was used to determine differences between M and OE in gene expression relative to C and to analyze plasma biomarkers. Mean treatment effects were separated using Tukey test at α = 0.05. Microbial raw sequencing reads were demultiplexed, quality-filtered and analyzed using QIIME 1.9.1. Feeding OE did not affect gut microbiota abundance and diversity, being