# Body weight of 35-day-old broilers is associated with proximal small intestinal inflammatory and oxidative pathways – A multi-omics study

## TL;DR

This study finds that higher body weight in young broiler chickens is linked to reduced inflammation and stronger antioxidant defenses in their small intestine.

## Contribution

The study identifies specific inflammatory and oxidative pathways in the small intestine associated with broiler body weight using a multi-omics approach.

## Key findings

- Jejunal transcriptome showed significant associations with broiler body weight.
- Low-weight broilers had enriched inflammatory pathways, while high-weight broilers had enriched anti-oxidative defense pathways.
- Cecal tonsil tissue in high-weight broilers showed enriched immune response pathways.

## Abstract

A major growth performance trait of modern-day broiler chickens is the ability to attain a high body weight (BW) within a short time. Here we identified parameters or factors significant associated with higher broiler BW using data on tissue (blood, jejunum, ileum and caecal tonsil) transcriptome, ileal and caecal digesta microbiota and metabolome, and blood biochemical and immune parameters. The data originated from 35-day-old Ross 308 male broilers reared under practical housing conditions and fed a non-starch polysaccharide-rich diet supplemented with either a probiotic or a postbiotic, including or not their carriers. Omics data were available for 72 broilers which were a subset of the 160 birds for which blood biochemical and immune parameters were available. The distribution of the BW did not significantly deviate from normality within the treatment groups and overall. Among all datasets, the jejunal tissue transcriptome was most associated with differences in broiler BW. Notably, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways associated with inflammatory response were significantly (p < 0.05) enriched in broilers with a low BW (e.g. Toll- and NOD-like signaling, phagosome, cytokine-cytokine receptor interaction, and cytosolic DNA sensing pathways) while gene ontology (GO) pathways associated with a response to toxic substances and anti-oxidative defenses were enriched in birds with high BW. In caecal tonsil tissue, broilers with a higher BW had pathways related to the immune response enriched (KEGG: cytokine-cytokine receptor interaction; GO: immune system process and response) with minor changes observed in their microbiota. Broiler BW was mainly associated with the tissue transcriptome, especially jejunum. In broilers with a higher BW, decreased expression of inflammation and increased expression anti-oxidative defense pathways were observed in jejunal tissue, while the caecal tonsil tissue showed a higher expression of immune pathways. Reducing inflammation and increasing anti-oxidative defenses in the proximal small intestine of broilers may provide future targets for improved broiler growth.