Evaluation of the metabolic status of Simmental dairy cows in early and mid lactation

Fifteen early-lactation cows and 15 mid-lactation cows were chosen for the analysis. Blood samples were collected to measure the beta-hydroxybutyrate (BHB), non-esterified fatty acids (NEFA), triglycerides (TG), glucose (Glu), total protein (TP), albumin (ALB), total bilirubin (TB), urea (U) and the activity of aspartate transaminase (AST) and gamma-glutamyl transferase (GGT). Earlyl-actation cows showed significantly higher (P<0.05) values of serum BHB and NEFA, and lower of (P<0.05) glycemia levels compared to mid-lactation cows. High lipomobilization (NEFA >0.4 mmol/l) and subclinical ketosis (BHB >1.2 mmol/L) were detected in 6 (40%) and 14 (94.4%) early-lactation cows, respectively, and in none of the mid lactation cows. AST activities above 100 IU/1 were detected in two early-lactation and none of the mid-lactation cows. TG concentrations below 0.12 mmol/l were found in 7 (44%) early-lactation and 2 (13.3%) mid-lactation cows. Glucose levels were below 2.5 mmol/l in 10 (66.6%) early-lactation and 5 (33.3%) mid-lactation cows. Early-lactation cows showed lower blood serum concentrations of TG (P>0.05), ALB (P>0.05), TP (P<0.05), U (P>0.05) and GTT (P>0.05) activities and higher concentrations of TB (P>0.05) and AST activities (P<0.05), as compared to mid-lactation cows. These metabolic characteristics were correlated with DMI and energy balance (EB). Blood serum values for glucose, TG, BHB, NEFA and AST showed that early-lactation cows suffered from metabolic disturbances, associated with ketosis, and some degree of hepatic lesions, probably due to fat infiltration. These serum parameters may have a key role in evaluating the metabolic status of dairy cows.