The objective of the present study was to investigate the metabolic and endocrine  status in Simmental dairy cows during peripartum period and mid lactation based on the relationships between blood growth hormone (GH), insulin, triiodothyrinine (T3), thyroxine (T4), glucose, beta-hydroxybutyrate (BHB), non-esterified fatty acids (NEFA), total lipid (TL), triglycerides (TG), total cholesterol, total protein (TP), albumin (ALB), urea and energy balance (EB). Fifteen late pregnant, 15 early lactation and 15 mid lactation cows were chosen for the analysis. Blood metabolic hormones, metabolites and EB were recorded. Early lactation cows had higher serum concentrations of GH, NEFA, BHB, TL and lower blood serum concentrations of T3, glucose, TG, total cholesterol, albumin and urea compared to late pregnant and/or mid lactation cows (P<0.05). Correlations between most hormones and metabolites were dependent (P<0.05) on the EB of cows, but this factor becomes unimportant under certain circumstances, depending on lactation period. Accordingly, correlations between insulin, BHB or NEFA and other parameters were not solely dependent on the EB, which may be associated with insulin resistance and fatty liver developing in cows.

Key words: Correlation, Dairy cows, Energy balance, Metabolic hormones, Metabolites