Double-Edged Metabolic Effects from Short-Term Feeding of Functionalized Wheat Bran to Mouse Revealed by Metabolomic Profiling

Experimental facility had a greater effect on growth performance, gut microbiome, and metabolome in weaned pigs than feeding diets containing subtherapeutic levels of antibiotics: A case study

The objective of this study was to define changes in the intestinal metabolome and microbiome associated with growth performance of weaned pigs fed subtherapeutic concentrations of antibiotics. Three experiments with the same antibiotic treatments were conducted on the same research farm but in two different facilities (nursery and wean-finish) using pigs weaned at 20-days of age from the same source herd and genotype, and fed the same diets formulated without antibiotics (NC) or with 0.01% chlortetracycline and 0.01% sulfamethazine (AB). Pigs were weighed and feed disappearance was determined on days (d) 10, 21, and 42 post-weaning to calculate average daily gain (ADG), average daily feed intake (ADFI), and gain:feed (G:F). On d 42, one pig/pen was selected for blood and ileal and cecal content collection. Targeted and untargeted metabolomic profiles were determined in serum and cecal contents using liquid chromatography-mass spectrometry, and composition of bacterial communities in intestinal content samples was determined by sequencing the V4 region of the 16s rRNA gene. Metabolomics and microbiome data were analyzed using diverse multivariate and machine learning methods. Pigs fed AB had significantly greater (P < 0.05) overall ADG and ADFI compared with those fed NC, and pig body weight, ADG, and G:F were also significantly different (P < 0.05) between experiments. Differences (P < 0.05) in serum metabolome along with ileal and cecal microbiome beta diversity were observed between experiments, but there were no differences in microbiome alpha diversity between experiments or treatments. Bacteria from the families Clostridiaceae, Streptomycetaceae, Peptostreptomycetaceae, and Leuconostocaceae were significant biomarkers for the AB treatment. In addition, pigs fed AB had increased serum arginine, histidine, lysine, and phenylalanine concentrations compared with NC. Percentage error from a random forest analysis indicated that most of the variation (8% error) in the microbiome was explained by the facility where the experiments were conducted. These results indicate that facility had a greater effect on growth performance, metabolome, and microbiome responses than feeding diets containing subtherapeutic levels of antibiotics.

Identification of Independent and Shared Metabolic Responses to High-Fiber and Antibiotic Treatments in Fecal Metabolome of Grow-Finish Pigs

Feeding high-fiber (HF) coproducts to grow–finish pigs as a cost-saving practice could compromise growth performance, while the inclusion of antibiotic growth promoters (AGPs) may improve it. The hindgut is a shared site of actions between fiber and AGPs. However, whether the metabolic interactions between them could occur in the digestive tract of pigs and then become detectable in feces have not been well-examined. In this study, wheat middling (WM), a HF coproduct, and bacitracin, a peptide antibiotic (AB), were fed to 128 grow–finish pigs for 98 days following a 2 × 2 factorial design, including antibiotic-free (AF) + low fiber (LF); AF + HF; AB + LF, and AB + HF, for growth and metabolic responses. The growth performance of the pigs was compromised by HF feedings but not by AB. A metabolomic analysis of fecal samples collected on day 28 of feeding showed that WM elicited comprehensive metabolic changes, especially in amino acids, fatty acids, and their microbial metabolites, while bacitracin caused selective metabolic changes, including in secondary bile acids. Limited metabolic interactions occurred between fiber and AB treatments. Moreover, the correlations between individual fecal metabolites and growth support the usage of fecal metabolome as a source of biomarkers for monitoring and predicting the metabolic performance of grow–finish pigs.