Observational study reveals heightened lipomobilisation and hepatic strain during early lactation in Holstein dairy cows, indicating metabolic vulnerability after calving.
Key Points
To assess the metabolic status and hepatic function of high-yielding Holstein dairy cows across late pregnancy, early lactation, and full lactation using circulating biochemical markers.
Assessed 36 clinically healthy Holstein cows categorized into late pregnancy (n = 12; 20 ± 15 days prepartum), early lactation (n = 12; 15 ± 12 days postpartum), and full lactation (n = 12; 81 ± 30 days postpartum).
Collected jugular vein blood samples to quantify serum markers of energy metabolism (glucose, triglycerides, total cholesterol, urea, NEFA, BHB) and liver damage enzymes (total bilirubin, AST, ALT, GGT).
Early lactation cows had significantly lower circulating glucose, triglycerides, total cholesterol, and urea (P < 0.05), alongside significantly higher NEFA and BHB concentrations (P < 0.05) compared to late-pregnant and full-lactation groups.
Serum total bilirubin and enzyme activities of AST, ALT, and GGT were markedly higher (P < 0.01) in lactating cows than in late-pregnant cows.
Lipomobilisation markers (NEFA and BHB) correlated positively with liver damage indices (total bilirubin, AST, ALT, GGT; P < 0.05) and negatively with liver synthesis metabolites (glucose, triglycerides, urea; P < 0.05).