Serum bile acid composition of the dog, cow, horse and human

The fractionation of serum bile acids was performed in the dog, cow, horse, and human by high performance liquid chromatography equipped with an immobilized 3 alpha-hydroxysteroid dehydrogenase (3 alpha-HSD) column. There were significant differences in the bile acid compositions, conjugation patterns and quantities of each bile acid among these animals. Cholic acid was the major primary bile acid in the dog and cow, which constituted 62.9% and 83.5%, respectively, whereas chenodeoxycholic acid was the major acid in the horse and human, which constituted 68.4% and 46.3%, respectively. Taurine conjugates were predominant in the dog and horse, which constituted 94.4% and 85.3%, respectively, whereas glycine conjugates were predominant in the cow and human, which constituted 31.0% and 49.4%, respectively. Although there were several unidentified peaks, it was confirmed that they had a hydroxy group at the C-3 alpha position by chromatographing the samples without the 3 alpha-HSD column.