The association between indicators of inflammation and liver variables during the transition period in high-yielding...

During the transition period, cows are confronted with infectious and inflammatory challenges leading to an acute phase response (APR) marked by increased hepatic synthesis of positive acute phase reactants (+AP) and a decrease in negative acute phase reactants (-AP). The aim of this study was to quantify the APR in 21 high-yielding dairy cows studied from 9 days before until 42 days after calving, and to assess the association between the APR, disease incidence and indicators of liver function. Repeated blood samples were analyzed for -AP (retinol, albumin, cholesterol), +AP (haptoglobin, caeruloplasmin), paraoxonase, and liver-associated variables (aspartate aminotransferase, γ-glutamyl transferase, bilirubin). All cows displayed postpartum decreases in -AP and paraoxonase, and increases in +AP and liver variables. When retrospectively categorized, cows presenting a stronger -AP decline displayed higher +AP and liver variables, and a higher disease incidence compared to cows with a milder decline. Altogether, typical changes in -AP and +AP identify the transition period as a time of increased inflammatory load. Group differences in liver variables suggest that a more severe APR may be associated with altered liver function. However, no causal relationship can be proven based on this observational dataset, and results should be interpreted cautiously.