The influence of metabolic adaptation during transition period on blood HbA1c and fructosamine concentration in dairy cows

The changes in the blood levels of fructosamine, total protein, albumin, haemoglobin and HbA1c levels were investigated in 10 Holstein cows. Blood samples were taken from the same animals three, two and one week prior to expected calving and then in the 1st, 2nd, 3rd, 4th and 5th week after calving. The concentration of total protein was lower before calving, then significantly increased after calving and remained high until the fifth week of lactation. The concentration of fructosamine was the lowest in the last week before calving, being significantly different in comparison with the third week before calving and in comparison with the first and fourth week of lactation. The concentration of haemoglobin was the highest in the third week before calving, then significantly decreased in the second week of lactation and remained on the same level until the fifth week of lactation. The level of HbA1c did not significantly change during the investigated period. A significant correlation between the concentrations of fructosamine and total protein was observed. In the second week before calving, a significant correlation between the concentrations of fructosamine and albumin was observed. The obtained results indicate the occurrence of substantial changes in the protein metabolism in dairy cows' organism within a few weeks around calving, which are related to the transient decrease in fructosamine concentration in the blood plasma. This fact should be taken into consideration when the energy status and glucose supply of animals are estimated on the basis of the fructosamine concentration.