Relationship between Indocyanine Green Clearance Test and Feed Intake and Impaired Hepatic Function in Dairy Cows

The purposes of this study were 1) to examine changes in the indocyanine green (ICG) clearance by feeding and 4-day fasting in dry cows, and (2) to investigate the relationship between ICG clearance and blood chemistry profile in postpartum cows. In 3 dry cows, post-feeding ICG half-life (T(1/2)) was shorter than the pre-feeding value, and post-fasting T(1/2) was longer than pre-feeding and post-feeding values. In 16 lactating cows, T(1/2) value at 2 weeks postpartum showed positive correlations with AST, T-Bil and γ-GTP. These results suggested that ICG clearance correlated with T-Bil and liver enzymes can be sensitive and accurate diagnostic marker for impaired liver function in dairy cows. In addition, ICG clearance is greatly affected by feeding and fasting.