Blood metabolomic characteristics in dairy cows treated with hepato-protectors during the transition period

Metabolomics is an important branch of system biology that studies metabolites to elucidate disease etiology and characteristics, to monitor disease and develop biomarkers. The negative energy balance is characterized by body resources mobilization, altered oxidative state, inflammatory and immune responses. Amino acids (AA) shortage can compromise tricarboxylic acid (TCA) cycle leading to ketogenesis and hyperketonemia. Preventive protocol for hyperketonemia can supports liver metabolism (hepato-protectors) through AA, vitamins as cyanocobalamin, inositol (insulin-mimetic), and α-lipoic acid (antioxidant). The aim of this study was to identify blood metabolome in dairy cows treated with hepato-protectors preventive protocol. A total of 60 Holstein-Friesian multiparous dairy cows from one farm were equally divided in (protocol number of ethical approvals 204359/2023): CTR or control group without treatment; and HEP or hepato-protectors group treated with two drugs, both administered at 12d pre-partum (pp) and 6d days in milk (DIM). The first one contained AA (acetylmethionine, alanine, arginine, threonine, glutamate), inositol, and cyanocobalamin (IM 2 ml/10 kg BW); the second one contained acetyl-methionine, α-lipoic acid, and cyanocobalamin (IM 70 ml/animal). Both drugs were administered at 12d pre-partum (pp) and 6d days in milk (DIM). Blood sampling was performed from the coccygeal vein at -21 and -7d pp, and at 7, 14, 28 DIM for serum metabolomics analysis by 1H-NMR. Differences in metabolites were assessed with a linear mixed-effects model. A p-value<0.05 was accepted, whereas a 0.05≤p-value≤0.10 was considered as trend to significance. The hyperketonemia prevalence was 10% in both groups at 7DIM, 23.3% in CTR and 16.7% in HEP at 14DIM, and 20% in CTR and 6.67% in HEP at 28DIM. A total of 50 metabolites were identified of which 26 differed by group (21 with p<0.05 and 5 with 0.05≤p≤0.10). The HEP had greater level of 13 metabolites compared to CTR (alanine, arginine, asparagine, choline, dimethyl-sulfone, glutamine, glycine, glyoxylate, histidine, methionine, myo-inositol, oacetyl- carnitine, and taurine), and lower concentrations of 13 metabolites (2,3-butanediol, 3-hydroxybutyrate, 3-hydroxyisobutyrate, acetate, acetone, dimethylamine, isoleucine, leucine, methanol, methionine sulfoxide, succinate, TMAO, and valine). Metabolites’ differences were 3.8% at 21pp, 42.3% at 7pp, 38.5% at 7DIM, 96.2% at 14DIM, and 80.8% at 28DIM. In conclusion, hepato-protectors improved the glucogenic AA, antioxidants, and fatty acid metabolism, with a probable improvement in the functioning of TCA cycle. Moreover, supplementation reduced the ketogenic AA and ketone bodies, markers of inflammation and oxidation, and ruminal methanogenic precursors, suggesting better management of the period.