Evaluation of the serum fructosamine test to monitor plasma glucose concentration in the transition dairy cow.

The usefulness of the serum fructosamine (Fser) to monitor the retrospective glucose concentrations in transitional dairy cows (n=17) was evaluated. In weekly blood samples (3 weeks before to 5 weeks after calving) concentrations of plasma glucose and serum fructosamine, beta-hydroxybutyrate (beta OHB) and total proteins were determined. The observed Fser concentrations (271+/-55 mean value, range 152-423 mumol/l) were within the range reported in the literature, and showed a progressive and significant decrease after calving. Mean plasma glucose concentration was 60.6+/-5.0 (range 39.9-82.2) mg/dl increasing from week 3 before calving to the week of calving and then decreasing during the next 5 weeks of lactation. This decrease was coincident with inverse relationships between plasma glucose and milk yield (P=0.03) and serum beta OHB (P<0.001). Linear regression analysis performed between serum fructosamine and (a) plasma glucose concentration of the same sampling and (b) plasma glucose concentration of 1, 2 and 3 weeks preceding the sampling, did not show significant and systematizing positive correlations. Persistent hypoproteinaemias that could affect the fructosamine concentrations were not found: mean value and range of serum proteins was 6.3+/-1.0 and 4.8-7.8 g/dl, respectively, and no correlation was found between serum proteins and Fser (P=0.26). Results did not support the possibility of retrospective monitoring of the plasma glucose concentration by serum fructosamine in dairy cows in the transition period.