[Glucose metabolism in sheep in different reproductive stages and with ketosis using the intravenous glucose tolerance test (IVGTT)].

Kinetic parameters of glucose metabolism were determined in 17 healthy ewes during different metabolic stages and in 8 spontaneously ketotic sheep by the IVGTT with low doses of glucose (0.8 mmol/kg) as well. The endogenous turnover rate (R) was calculated by using the total clearance (Cl), derived from the IVGTT. The values of R, determined in healthy ewes by this technique are in agreement with values presented in the literature, which were derived from kinetic studies with 3H- or 14C-labeled glucose. There were no differences in the mean values of R and Cl in non-pregnant, highly pregnant and ketotic ewes in our study. The plasma concentration of glucose (C) was significantly correlated with R in highly pregnant healthy and ketotic ewes; there was no such correlation in the group of non-pregnant and early pregnant sheep. In highly pregnant ketotic ewes the mean value of C was lower than in healthy ewes but there was no significant correlation between the plasma concentration of glucose and that of 3-hydroxybutyrate. It is concluded from the study, that the control of glucostasis fails frequently during late pregnancy in ewes and that ketosis of sheep is related closer to the excessive lipid mobilisation than to disturbance of glucostasis.