Different Effects of Probiotics and Antibiotics on the Composition of Microbiota, SCFAs Concentrations and FFAR2/3 mRNA Expression in Broiler Chickens.

AIMS The aims of this study were to investigate the effects of probiotics and antibiotics on microbial composition, short chain fatty acids (SCFAs) concentration and free fatty acid receptor 2/3 (FFAR2/3) expression in boiler chickens. METHODS AND RESULTS 150 one-day-old male broilers were randomly allocated into 3 groups, control (CON) group, probiotics (PB) group and antibiotics (ATB) group. Results indicated that PB improved the average body weight from 1 d to 21 d and feed intake from 21 d to 42 d (p< 0.05), while ATB improved the feed efficiency from 1 d to 42 d (p< 0.05). Based on 16s rRNA sequencing, PB treatment increased the amount of kingdom bacteria, and the relative abundance of the main bacteria including acetate and butyrate producing bacteria of phylum Firmicutes, family Ruminococcaceae and genus Faecalibacterium. ATB treatment also increased the relative abundance of phylum Firmicutes, family Ruminococcaceae and Lachnospiraceae, however it introduced some pathogenic bacteria, such as bacteria of family Rikenellaceae and Enterobacteriaceae. Gas chromatography and mass spectrometry (GC-MS) assay revealed PB increased acetate and butyrate concentrations at both 21 d and 42 d, and propionate at 42 d in the colorectum. Moreover, qRT-PCR analysis showed PB treatment significantly activated the FFAR2/3 mRNA expressions. On the contrast, ATB treatment lowered the colorectal propionate at 21 d, and decreased acetate, propionate, and butyrate concentrations at 42 d, accompanied with decreased FFAR2/3 mRNA expressions. CONCLUSIONS Compare to the CON birds, an enriched SCFAs producing bacteria with higher SCFAs contents and activated FFAR2/3 expressions are prominent features of PB birds. However, antibiotics treatment plays the reverse effect compared to PB treatment. SIGNIFICANCE AND IMPACT OF THE STUDY This study brings a significant idea that less SCFAs concentration may be another reason why the antibiotics inhibit the immune system development and immunity of the body.