3.3　Metabolomic analysis revealed that nine variab...

3.3　Metabolomic analysis revealed that nine variables were different between control and model groups

In the 30 samples，858 metabolomic features in total were detected by GC-MS and were used to form a matrix of size 30(samples)×858(variables).No significant difference was observed among the three groups when 858 variables were used in MANOVA analysis or PCA analysis.However，when each variable was considered alone in turn by ANOVA，comparing either of the model groups with the control group，significant differences of both comparisons were observed.Twenty-two variables were found significantly different at p＜0.05 between the cattle albumin group and the control group(Table 3)and 19 variables differed sharply between the ovalbumin and control groups(Table 4).Among these，nine variables significantly changed in both model groups compared with the control group.By using these nine variables in a new MANOVA analysis，significant differences appeared between control group and model groups(Figure 1a).The clustering between the control group and the model groups also became clear in PCA when the matrix was reduced to 30(samples)×9(variables)with only the selected nine variables kept and the other 849 variables removed(Figure 1b).

Figure 1　Loading plot of the three groups by MANOVA based on p＜0.01(circles，control；crosses，cattle albumin group；squares，ovalbumin group)

(a)Scattering plot of the three groups by MANOVA based on nine selected metabolite peaks.(b)PCA score plot of the three groups based on nine selected metabolite peaks.The three groups were obviously separated by MANOVA and PCA when only nine selected variables were used

Table 3　Variables responsible for the classification of the cattle albumin group and the control group

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a Typical ion fragmentation for the variables
p values were calculated on the basis of ANOVA(significance at p＜0.05)

Table 4　Variables significantly different between the ovalbumin group and the control group

Continued table

a Typical ion fragmentation for the variables
p values were calculated on the basis of ANOVA(significance at p＜0.05)