[Gamma-glutamyltransferase activity in the blood of calves].

The activity of gMT in the blood serum of calves was studied in relation to the age, concentration of total immunoglobulins (Ig) and protein (TP) and to the volume of colostrum taken in by the calves during the first post-partum sucking. Before sucking the serum activity of gMT in newborn calves is low; later it assumes an ascending tendency, the maximum activity being recorded in the 24th hour from birth. A continuous decrease follows in the subsequent postnatal period and the physiological values (of adult cattle) are obtained in the sixth to seventh weeks of age. A marked correlation was found between the values of Ig and gMT (r = 0.9988), and TP and gMT (r = 0.9911), in newborn calves at the age of 48 hours. A highly significant difference was also found in the activity of gMT (P less than 0.01) in calves with different post-partum Ig concentrations. Attention is drawn to the significant difference in the serum activity of gMT (P less than 0.05), Ig (P less than 0.01) and TP (P less than 0.05) in calves given different amounts of the first colostrum. The results of the study can be used for the evaluation of metabolic tests in calves during the early postnatal period.