Serum fructosamine concentrations in relation to metabolic changes during late pregnancy and early lactation in mares.

The changes in blood serum fructosamine concentrations as indicators of glycaemia during a longer period of time were investigated in mares during late pregnancy and early lactation, as well as their relationship to the changes in the concentration of biochemical indicators of energetic status. The samples were taken from eleven mares on 60 +/- 10 and 20 +/- 10 days before foaling, and 20 +/- 10 and 60 +/- 10 days after foaling. Concentrations of serum fructosamine, non-esterified fatty acids and triglycerides were higher during late pregnancy (from P < 0.05 to P < 0.0005), while the concentrations of beta- hydroxybutyrate increased significantly (P < 0.00001) during early lactation. A significant correlation between the concentrations of fructosamine and metabolic parameters was observed. The results indicate a relationship between energetic status and serum fructosamine in mares. Higher concentrations of fructosamine are related to the adaptation to late pregnancy. Therefore, the measurement of the serum fructosamine concentrations could serve as an indicator of energetic status of mares during pregnancy and lactation.