Fig. 4

Effects of MLP on the plasma metabolites of laying hens challenged with LPS derived from Escherichia coli. A Partial least squares-discriminant analysis (PLS-DA) model of plasma metabolites. The x- and y-axes denote the first and second principal components, respectively. B Volcano plot of differentially plasma metabolites. C VIP scores analysis for differential plasma metabolites. Top 20 metabolites among VIP scores > 1 were selected and ranked based on VIP scores. The length of the bar indicates the value of the contribution of this metabolite to the difference between the two groups. The color of the bar indicates the significance of the difference between the two groups of samples. * means P < 0.05, ** means P < 0.01 and *** means P < 0.001. D Classification of differential metabolites in the HMDB database. E KEGG signaling pathways enriched by different metabolites (P < 0.05, VIP-Pred-OPLS-DA > 1). The size of the dots indicates the number of differentially abundant metabolites and the color of the dots represents the P-value. CN, Basal diet; CN-LPS, Basal diet + LPS; MLP-LPS, Basal diet + MLP + LPS