Abstract:
Restrictions on the use of antibiotics in the poultry industry stimulate the development of
alternative nutritional solutions to maintain or improve poultry health. This requires more insight
in the modulatory effects of feed additives on the immune system and microbiota composition.
Compounds known to influence the innate immune system and microbiota composition were
selected and screened in vitro, in ovo, and in vivo. Among all compounds, 57 enhanced NK cell
activation, 56 increased phagocytosis, and 22 increased NO production of the macrophage cell line
HD11 in vitro. Based on these results, availability and regulatory status, six compounds were selected
for further analysis. None of these compounds showed negative effects on growth, hatchability,
and feed conversion in in ovo and in vivo studies. Based on the most interesting numerical results and
highest future potential feasibility, two compounds were analyzed further. Administration of glucose
oligosaccharide and long-chain glucomannan in vivo both enhanced activation of intraepithelial NK
cells and led to increased relative abundance of lactic acid bacteria (LAB) amongst ileum and ceca
microbiota after seven days of supplementation. Positive correlations between NK cell subsets and
activation, and relative abundance of LAB suggest the involvement of microbiota in the modulation
of the function of intraepithelial NK cells. This study identifies glucose oligosaccharide and longchain glucomannan supplementation as effective nutritional strategies to modulate the intestinal
microbiota composition and strengthen the intraepithelial innate immune system.
