Effects of wild blueberry (Vaccinium angustifolium) pomace feeding on gut microbiota and blood metabolites in free-range pastured broiler chickens

There is a need to develop cost-effective approaches to modulate gut microbiota, promote bird health, and prevent infections in pasture-raised broiler chickens. The present study evaluated the efficacy of organic wild blueberry (Vaccinium angustifolium) also called low-bush blueberry pomace (LBBP)-supplemented feed to modulate the chicken gut microbiota, and blood metabolites in order to improve bird health and productivity. Slow-growing broiler chickens were reared on pasture up to 64 D for sampling after 2 wk of treatment during brooding with 0, 1, and 2% LBBP in feed. Intestinal samples were collected at different time-points throughout the trial for bacterial culture and microbial community analysis by 16S rRNA gene sequencing using Illumina MiSeq. Blood sera were also analyzed for metabolites at each sampling time. Of the 14 bacterial phyla, the predominant taxa across all sampling time-points were Firmicutes, Proteobacteria, Bacteroidetes, and Tenericutes, representing >97% of all sequences. Bacteroidetes seemed to be replacing Firmicutes by LBBP supplementation, with the most noticeable effect at day 64 with 1% LBBP. LBBP inclusion enriched Lactobacillus, Bacteroides, and Bifidobacterium, while Escherichia coli, Clostridium_Clostridiaceae, Helicobacter, and Enterococcus showed higher abundances in control birds at the end of trial. Principal co-ordinate analysis showed a clear clustering of the intestinal samples from control and LBBP-treated groups at day 29. Application of LBBP resulted in a decrease (P < 0.05) in cholesterol at day 21, and an increase (P < 0.05) in high-density lipoprotein cholesterol in 14-day-old broilers. Higher (P < 0.05) levels of phosphorus, magnesium, and globulin at day 21 as well as iron and albumin at day 36 were also observed in 1% LBBP-fed birds. Despite limitations consisting essentially of low sampled birds for measurements, this study indicated that dietary supplementation of LBBP could positively influence gut microbiota and blood metabolites that may contribute to the overall health of pasture-raised broiler chickens.