Effect of Carotenoids, Oligosaccharides and Anthocyanins on Growth Performance, Immunological Parameters and Intestinal Morphology in Broiler Chickens Challenged with Escherichia coli Lipopolysaccharide

SIMPLE SUMMARY: In recent years, substitution or reduction of antibiotic application has become a general aim in poultry industry, after concerns about multiresistant bacteria appeared. Accordingly, many natural compounds are used as potential immunostimulants to enhance immune responses. In this research, the effects of carotenoids, oligosaccharides and anthocyanins were investigated on chicken inflammatory cytokines and receptors. Being part of the innate immune system, cytokines are peptides which take part in signaling processes between cells and regulate inflammatory responses. Toll-like receptors are cell surface receptors which bind to antigens specifically. Gene expression levels of some cytokines such as interleukin-1β, interleukin-6, interferon-α, interferon-γ and toll-like receptors such as toll-like receptor 4, toll-like receptor 5 were evaluated in chicken spleen and ileum by Real Time Polymerase Chain Reaction (Real Time PCR) analyses. Relative gene expression level of splenic interleukin-1β decreased in carotenoid-, oligosaccharide- and anthocyanin treated chickens, and relative mRNA level of splenic interleukin-6 was lower in birds fed carotenoid supplement, which could represent a beneficial effect of mentioned natural compounds. Effects of compounds were also examined on gut morphology, where natural agents may result in better absorptive functions. ABSTRACT: This study was conducted to investigate the effect of carotenoid, oligosaccharide and anthocyanin supplementation in broiler diets under Escherichia coli lipopolysaccharide (LPS) challenge. Ross 308 chickens were fed 5 diets: basal diet (control diet), diet supplemented with β-glucan in 0.05% (positive control) and diets with 0.5% carotenoid-, oligosaccharide- or anthocyanin contents. On the 26th days of age, chickens were challenged intraperitoneally 2 mg LPS per kg of body weight. 12 h after injection, birds were euthanized, then spleen and ileum samples were collected. LPS induced increased relative mRNA expression of splenic (p = 0.0445) and ileal (p = 0.0435) interleukin-1β (IL-1β), which was lower in the spleen in carotenoid (p = 0.0114), oligosaccharide (p = 0.0497) and anthocyanin (p = 0.0303)-treated chickens compared to LPS-injected control birds. Dietary supplementation of carotenoids also decreased relative gene expression of splenic interleukin-6 (IL-6) (p = 0.0325). In the ileum, β-glucan supplementation showed lower relative mRNA expression of toll-like receptor 5 (TLR-5) (p = 0.0387) compared to anthocyanin treatment. Gene expression of both splenic and ileal interferon-α (IFN-α), interferon-γ (IFN-γ), toll-like receptor 4 (TLR-4) and toll-like receptor 5 (TLR-5) were not influenced by dietary supplements. In conclusion, carotenoids, oligosaccharides and anthocyanins could partially mitigate the immune stress caused by LPS challenge. All of the compounds impacted longer villus height (p < 0.0001), villus height:crypt depth ratios were higher after β-glucan (p < 0.0001) and anthocyanin (p = 0.0063) supplementations and thickened mucosa was observed in β-glucan (p < 0.0001), oligosaccharide (p < 0.0001) and anthocyanin (p = 0.048) treatments. All of these findings could represent a more effective absorption of nutrients.