Serum fructosamine levels in dairy cows related to metabolic status in early lactation.

Serum levels of fructosamine were assayed in 57 samples from 23 Norwegian Red Cattle dairy cows in early lactation. The animals were assigned to a 2 factorial feeding experiment. The groups differed in energy and protein supply. All samples were collected before morning feeding. The relationship between fructosamine levels and the plasma concentrations of glucose, acetoacetate, free fatty acids, total cholesterol, lipoproteins, triglycerides, total proteins, progesterone and to weight and energy balance was studied. The overall mean fructosamine level was 1.41 ± 0.20 mmol/1 ranging from 0.92–1.92 mmol/1. Significant relationships were recorded between fructosamine and the concentrations of glucose, acetoacetate, free fatty acids, triglyceride, total cholesterol and energy and weight balance. Free fatty acids and cholesterol showed the best correlation with fructosamine (r =–0.67 and 0.70, respectively, p < 0.001). The levels of fructosamine increased significantly between 2 and 4 weeks and between 4 and 8 weeks after calving. Animals with a weight gain during 3 weeks prior to fructosamine measurement had higher fructosamine levels than those showing a weight loss (<–7 kg/week) (p < 0.05). The results indicate that serum fructosamine levels in cows may be of interest as an indicator of metabolic status in the early stages of lactation.