The global turkey industry is confronted with emerging challenges regarding health and welfare. Performance and disease resilience are directly linked to gut health. A clear definition of a healthy gut is a prerequisite to developing new strategies for improved gut health and, thus, general health, welfare and productivity. To date, detailed knowledge about gut health characteristics, especially during the critical fattening period, is still lacking for turkeys. Therefore, the goal of this study was to describe the morphology, microbiota, and metabolome along the intestinal tract of clinically healthy Salmonella- and Campylobacter-free commercial turkey hens throughout the fattening period from 7 to 10 wk posthatch, and obtain information on the stability of the investigated values over time. Feed changes were avoided directly preceding and during the investigation period. Investigation methods included histomorphometric measurement of intestinal villi and crypts, Illumina-sequencing for microbiota analysis, and proton nuclear magnetic resonance spectroscopy for metabolite identification and quantification. Overall, the study demonstrated a high repeatability across all 3 experiments and gut section differences observed coincided with their functions. It was demonstrated that gut maturation, defined by gut microbiota stability, is reached earlier in the ceca than any other intestinal section where morphological changes are ongoing throughout the fattening period. Therefore, the present study provides valuable information necessary to advise future studies on the development and implementation of measures to support gut maturation and establish a protective microbiota in commercial turkeys.

Campylobacter (C.) jejuni and C. coli are common zoonotic bacteria in pigs, which typically act as asymptomatic carriers. However, the effects of Campylobacter colonisation on the porcine intestinal microbiota and metabolome remain poorly understood. This study investigated microbiome and metabolome alterations associated with co-colonisation by C. jejuni and C. coli in the different intestinal segments of pigs. Thirty-two weaned piglets were assigned to a control group and a group inoculated with C. coli ST5777/CT828 and C. jejuni ST122/CT206. Four weeks post inoculation, jejunal and caecal contents were analysed for Campylobacter counts, metabolite profiles and microbial composition. All animals remained clinically healthy. Both Campylobacter species colonised the jejunum and caecum, with higher C. coli counts in the caecum. Campylobacter-colonised pigs showed significantly altered metabolite profiles, including reduced cysteine and urea and increased glycine in the jejunum, as well as elevated 3-hydroxybutyrate levels in the caecum. In contrast, short-chain fatty acid concentrations in the caecum were unaffected by infection. Microbiota analysis revealed a significant reduction in caecal alpha diversity, whereas jejunal diversity remained unchanged. Infected pigs exhibited increased relative abundances of Lactobacillaceae and Bifidobacteriaceae and a decreased abundance of Pseudomonadota, including Enterobacteriaceae. In conclusion, Campylobacter co-colonisation induces distinct microbiome and metabolome alterations in pigs despite the absence of clinical disease. These findings highlight complex host-microbiota–pathogen interactions that may be relevant for future Campylobacter control strategies in pig production.