Neonatal development of the gut of broilers is influenced by genetics and management

Neonatal development of the gastro-intestinal tract is dependent on an interplay between gut microbiota and the host mucosal tissue. Several intrinsic and extrinsic factors have an effect on the interplay. Here, we demonstrate the impact of one internal and one external factor on gut microbiome development and immune status during neonatal development of broilers. To this end we used (1) broiler lines differing in their genetic background and (2) commercial birds that were treated with a therapeutic dose of an antibiotic at day 1 via the
drinking water. In genetically different broiler lines X and Y, kept under the same management conditions, microbiota composition in jejunum was significantly different over period of two weeks between the lines. Furthermore, by comparing the two lines, trends were observed in the microbiota data at the genus level. Different temporal intestinal gene expression patterns of the gut mucosal tissues were observed when comparing the genetically different broiler
lines. Birds from line X had higher expression of genes associated with immunological related processes at day 0. Genes related to cell cycle related processes showed higher expression over a period of two weeks in line Y. The early short antibiotic treatment of broilers affected both the microbiota composition in the intestinal tract, as well as the intestinal gene expression
over a period of at least two weeks. Significant differences were observed after functional analysis of the mucosal gene expression profiles in jejunum. Especially on day 5 lower activity of immune processes were observed in the antibiotic treated birds compared to their respective controls. To validate these functional changes, immune cells in the small intestinal mucosa were
stained and a significant lower number of KUL01+ cells were observed in the small intestinal tissue of antibiotic treated birds. The results indicate that both intrinsic factors (host genetics) and extrinsic factors (short antibiotic treatment) have an effect on the early life microbial colonization of the broiler gut and on the mucosal gene expression profiles. This suggest that also the interplay between microbiota and host mucosal cells is affected by these intrinsic and
extrinsic factors. We conclude that intestinal development is a complex process and that both genetic and (early life) management factors influence the interplay between the intestinal microbiome and host intestinal mucosal tissue. Therefore the interaction between genetic background and early life microbial colonization is a major driver of traits on performance and health of broilers.