Dietaryl-threonine supplementation attenuates lipopolysaccharide-induced inflammatory responses and intestinal barrier damage of broiler chickens at an early age

Abstract

AbstractThis study was conducted to investigate the protective effects ofl-threonine (l-Thr) supplementation on growth performance, inflammatory responses and intestinal barrier function of young broilers challenged with lipopolysaccharide (LPS). A total of 144 1-d-old male chicks were allocated to one of three treatments: non-challenged broilers fed a basal diet (control group), LPS-challenged broilers fed a basal diet withoutl-Thr supplementation and LPS-challenged broilers fed a basal diet supplemented with 3·0 g/kgl-Thr. LPS challenge was performed intraperitoneally at 17, 19 and 21 d of age, whereas the control group received physiological saline injection. Compared with the control group, LPS challenge impaired growth performance of broilers, andl-Thr administration reversed LPS-induced increase in feed/gain ratio. LPS challenge elevated blood cell counts related to inflammation, and pro-inflammatory cytokine concentrations in serum (IL-1βand TNF-α), spleen (IL-1βand TNF-α) and intestinal mucosa (jejunal interferon-γ(IFN-γ) and ileal IL-1β). The concentrations of intestinal cytokines in LPS-challenged broilers were reduced byl-Thr supplementation. LPS administration increased circulatingd-lactic acid concentration, whereas it reduced villus height, the ratio between villus height and crypt depth and goblet density in both jejunum and ileum. LPS-induced decreases in jejunal villus height, intestinal villus height:crypt depth ratio and ileal goblet cell density were reversed withl-Thr supplementation. Similarly, LPS-induced alterations in the intestinal mRNA abundances of genes related to intestinal inflammation and barrier function (jejunal toll-like receptor 4,IFN-γand claudin-3, and ilealIL-1βand zonula occludens-1) were normalised withl-Thr administration. It can be concluded thatl-Thr supplementation could attenuate LPS-induced inflammatory responses and intestinal barrier damage of young broilers.