Characterisation of Bile Acid Metabolomics in Cattle with Chronic Liver Disease: Advancing Diagnostic Biochemistry in North Central Nigeria

Chronic liver disease in cattle, encompassing fasciolosis-associated cirrhosis, hepatic lipidosis, and toxic hepatopathy, is associated with dysregulation of bile acid synthesis, conjugation, and enterohepatic cycling, yet bile acid metabolomics has not been applied to advance hepatic diagnostics in Nigerian veterinary medicine. This doctoral study characterised the serum bile acid metabolome in cattle with chronic liver disease at farms and veterinary clinics in Benue, Kogi, and Niger States, North Central Nigeria, using targeted bile acid metabolomics to generate novel diagnostic knowledge. One hundred and twenty cattle with histopathologically confirmed chronic liver disease and sixty healthy controls were enrolled. Serum samples were processed for targeted quantification of thirty-seven primary and secondary bile acids including cholic acid, chenodeoxycholic acid, deoxycholic acid, lithocholic acid, and their glycine and taurine conjugates by liquid chromatography-tandem mass spectrometry. Hepatic fibrosis severity was scored by modified Metavir scoring of liver biopsy specimens. Cattle with advanced hepatic fibrosis showed marked elevation of total primary bile acids with a significant shift in the primary-to-secondary bile acid ratio, reflecting impaired intestinal biotransformation. Taurine-conjugated bile acids were disproportionately elevated relative to glycine conjugates in cases with concurrent cholestasis. A five-bile-acid diagnostic panel achieved an area under the receiver operating characteristic curve of 0.97 for advanced fibrosis versus no fibrosis. This doctoral study provides the first bile acid metabolomics dataset for chronic liver disease in Nigerian cattle and introduces a high-accuracy metabolomics-based diagnostic tool applicable to North Central veterinary referral practice. Keywords: bile acid metabolomics, chronic liver disease, hepatic fibrosis, cattle, North Central Nigeria.