PS12-4. Characterizing Liver Health Index Fluctuations in Peripartum Dairy Cows and Their Association with Postpartum Lactational Performance and Health.

Abstract The objectives were to assess the correlation between prepartum and postpartum liver health index (LHI), and associations between prepartum LHI, postpartum disease incidence, and lactational performance. Holstein cows (n = 243; 62 nulliparous, 64 primiparous, 117 multiparous) from a dairy in WA were sampled for blood collection at −7 d and +7 d relative to calving. Serum albumin (Alb), cholesterol (Chol), and bilirubin (Bili) concentrations were quantified via colorimetric assays, and LHI was calculated as: [(Alb − μAlb)/σAlb] + [(Chol − μChol)/σChol] − [(Bili − μBili)/σBili], where μ = mean and σ = standard deviation. Prepartum cows were categorized into quartiles (Q1 = 60 cows, Q2 = 60 cows, Q3 = 62 cows, Q4 = 61 cows) based on d − 7 LHI values, with upper and lower quartiles representing high and low LHI. Metritis and dyscalcemia diagnosed within 10 DIM comprised the postpartum disease outcome (combined diseases), total milk production and culling risk were evaluated by 300 DIM. Statistical analyses included Pearson correlations, logistic regression, and ANOVA using SAS. In addition to quartile-based analyses, contrasts comparing lower (Q1 + Q2) versus upper (Q3 + Q4) LHI groups were performed. A moderate positive correlation between pre- and postpartum LHI was observed (r = 0.53; P < 0.01), indicating relative stability of liver health status across the transition period. When analyzed by individual quartiles, prepartum LHI was not associated with disease risk (P = 0.18); however, cows in the lower two quartiles exhibited a greater incidence of postpartum disease compared with those in the upper two quartiles (66.9% vs. 51.8%; P = 0.05). Prepartum LHI was associated with differences in total milk production (P = 0.02) and culling risk (P = 0.03). Cows in Q2 produced less milk than cows in Q4 (9,890 ± 423 vs. 11,765 ± 435 kg), and cows in Q1 and Q2 had greater culling risk than cows in Q4 (28.7%, 25.5%, and 8.5%, respectively). Prepartum LHI is moderately correlated with postpartum LHI and is associated with subsequent lactational performance and survival, suggesting its utility as an early biomarker of transition cow health and productivity.