Supplemental Xylooligosaccharide Attenuates Growth Retardation and Intestinal Damage in Broiler Chickens Challenged by Avian Pathogenic Escherichia coli

This study was conducted to investigate the protective effects of xylooligosaccharide (XOS) on the growth performance and intestinal health of broilers challenged by avian pathogenic Escherichia coli (APEC). A total of 144 newly hatched male Lingnan yellow-feathered broilers were randomly divided into three groups (six replicates/group): a control (CON) group, an APEC group and an XOS group (APEC-challenged broilers supplemented with 1600 mg/kg XOS). Birds in the APEC and XOS groups were orally challenged with APEC from 7 to 12 d of age. Growth performance and intestinal health-related parameters were determined on d 13 and 17. The reductions (p < 0.05) in final body weight, average daily gain and elevation (p < 0.05) in intestinal APEC colonization in challenged broilers were counteracted by the XOS addition, which also alleviated the APEC-induced reductions (p < 0.05) in jejunal goblet cell count and density in broilers on d 17. Supplementing with XOS increased (p < 0.05) jejunal villus height and crypt depth, coupled with occludin and zonula occluden-1 expression, on d 17, and diminished the change (p < 0.05) in the jejunal inflammatory cytokine expression profile in a time-dependent manner. Moreover, cecal counts of total bacteria and Lactobacillus in challenged broilers were augmented (p < 0.05) by the XOS addition, which also mitigated APEC-induced reductions (p < 0.05) in cecal acetate, butyrate and valerate concentrations in broilers on d 13 or 17. Supplementing with XOS blocked the increases (p < 0.05) in the expression of cecal E. coli virulence genes relA and ompR on d 13 along with the expression of fimH and csgA on d 17. XOS alleviated APEC-induced growth retardation and intestinal disruption in broilers partially by restraining the intestinal colonization of APEC. Furthermore, the improvements in cecal microbiota and fermentation pattern, along with attenuation of cecal E. coli virulence resulting from XOS supplementation, could also support the maintenance of intestinal health in APEC-challenged broilers.