Multilevel evaluation of prebiotic and probiotic supplementations, heat stress, and genetic strain effects on blood and intestinal epithelial cells of chicken

Abstract

There is a need to assess how dietary strategies might effectively benefit bird health, performance, and the ability to deal with environmental variability. Metabolomics is suggested as a useful approach for assessing chicken responses to management interventions and identifying key biomarkers and pathways associated with bird health and production. The purpose of this study was to examine the utility of metabolomics for assessing physiological responses of chickens of different genetic backgrounds to different pre- and probiotic supplements. Feeding Chondrus crispus seaweed as a source of prebiotic for 3 weeks had little effect on leukocyte counts and classic blood chemistry but significantly impacted feed intake, feed to egg ratio, and weight gain. In contrast, longer term supplementation with Chondrus crispus or Ascophyllum nodusum for 45 weeks affected plasma protein, enzyme profiles, and several blood chemistry values, with little effect on hen leukocyte counts and overall performance. Heat stress also affected the leukocyte count and some plasma chemistry parameters. Through the NMR approach, we provided quantitative data on 57 plasma and 59 intestinal epithelial cell metabolites to provide a resource to study physiological responses and biological functions in laying hens. We also detected differentially expressed metabolites and linked them to metabolic pathways using the KEGG database. In broilers, we assessed the impacts of Bacillus subtilis probiotic delivery routes on the plasma metabolome and identified nine, four, and three metabolic pathways associated with in-ovo, in-feed, and in-water probiotic treatments, respectively. Overall, our results showed that chicken plasma and epithelial cell metabolome were very sensitive to internal and external stimuli, including pre- and probiotic supplementation, heat stress, and genetic strain, often when production or more classical blood indicators of stress were not affected. These findings suggested that metabolomics could be successfully used to address the challenge of identifying pathways and mechanisms that explain the health effects of genetic and environmental factors.