Principal component analysis (PCA) score plots of low-calcium diet rats, normal-calcium diet rats and calcium-supplement diet rats (n = 36). The maintained low-calcium group (MLCG) rats are indicated by blue circles, the normal-calcium group (NCG) rats by red circles, and the calcium-supplement group (CSG) by black triangles. The R2Y value represents the goodness of fit of the model, and the Q2 value represents the predictability of the models. (A) Before calcium supplementation (for six components R2Y = 53.9%, Q2 = 23.4%); (B) after calcium supplementation for 1 week (for five components R2Y = 55.3%, Q2 = 26.1%); (C) after calcium supplementation for 4 weeks (for five components R2Y = 55.6%, Q2 = 28.3%). Comp, component. t, component 1; t, component 2.