Table 3.

Significantly differentially ruminal metabolites of Angus heifers in the comparison between the LRFI and HRFI groups^a.

No.	Metabolites	Formula	VIPb	P-valuec	Fold change	Trendd
Protein digestion and absorption
1	L-Proline	C5H9NO2	1.3329	P <0.01	0.5218	Down
2	L-Phenylalanine	C9H11NO2	1.4357	P <0.01	0.8922	Down
3	L-Isoleucine	C6H13NO2	1.4295	P <0.01	0.8742	Down
4	Piperidine	C5H11N	1.4627	P <0.01	0.7622	Down
Linoleic acid metabolism
5	Gamma-Linolenic acid	C18H30O2	1.4264	P <0.05	1.2201	Up
6	9,10-DHOME	C18H34O4	1.6152	P <0.01	0.8576	Down
7	9-OxoODE	C18H30O3	1.7472	P <0.01	0.9578	Down
Lysine degradation
8	S-Glutaryldihydrolipoamide	C13H23NO4S2	1.5437	P <0.01	0.5526	Down
9	(3S)-3,6-Diaminohexanoate	C6H14N2O2	1.4846	P <0.05	0.7140	Down
10	Glutaric acid	C5H8O4	1.1763	P <0.05	0.9446	Down
Fatty acid degradation
11	Palmitic acid	C16H32O2	1.1059	P <0.05	0.9261	Down

^aHRFI, high residual feed intake; LRFI, low residual feed intake.

^bVIP, variable importance in the projection.

^cP-values are derived using a Student's t-test to assess the differences between HRFI and LRFI groups.

^dDown, downregulated; up, upregulated.