highly significantp < 0.01
BUN showed a significant positive correlation with lumichrome, squamolinone, PC (20:2 (11Z, 14Z)/18:3 (9Z, 12Z, 15Z), and PC [14:0/20:2 (11Z, 14Z)] ( p < 0.05) and a highly significant negative correlation with riboflavin (vitamin B 2 ), riboflavin, succinic acid, and geniposidic acid ( p < 0.01).