The overall effect of LPS over time was investigated with a multilevel PCA (Fig. 2). The first component of the multilevel PCA opposes the observations at t=0 (negative coordinates on this axis) to the observations at t=+4 (positive coordinates on this axis), this time step corresponding to the peak of LPS effect. The second component opposes the observations at t=+24 (positive coordinates on this axis) to the other observation times (negative coordinates on this axis). The representation of the variables shows that the first axis is mainly driven by an opposition between free fatty acids (FFA), bilirubin, temperature and cortisol (high measures at t=+4), and white cell count and glucose (low measures at t=+4). The second axis of the PCA is driven by L/G ratio and platelet count that are high at t=+1. Fig. 2Multilevel PCA on the biological variables responding to LPS. Colors represent the time step; Black: t=0; Red: t=+1; Green: t=+4; Blue: t=+24; a: Projection of the individuals on dimensions 1 - 2; b: Projection of the variables on dimensions 1 - 2