Variations of energy-related biochemical metabolites during transition period in dairy cows

This study describes the variation of serum biochemical metabolites during transition period in dairy cows. Blood samples were obtained on days 22 and 8 prepartum and days 7 and 21 postpartum (pp), to determine total protein, albumin, blood urea nitrogen, cholesterol, magnesium, inorganic phosphorus, calcium, glucose, triglyceride, aspartate aminotransferase (AST), β-hydroxybutyrate (BHBA), and non-esterified fatty acid (NEFA). NEFA concentrations during the pre-fresh period had a positive correlation with triglyceride, BHBA, and AST during post-calving days. This finding indicates that NEFA testing during the last days of a dry period is a reliable predictor of fat mobilization and energy status during this transition period. Serum glucose showed no strong correlations with other energy-related metabolites. AST was significantly correlated to triglyceride, BHBA, NEFA, cholesterol, and glucose at day 8 pp. AST also showed significant correlation with triglyceride concentrations at days −8 and +8 relating to parturition. In addition, AST was significantly correlated to BHBA and NEFA at day 21 pp.