Authors : Hiromi Terao, Masanori Fujita, Akemi Tsumagari, Toshihisa Sugino and Takashi Bungo
Abstract: Glucose tolerance and tissue sensitivity to glucose are considered to be important factors controlling metabolism around parturition. The objective of this study was to estimate the changes of physiological response to Glucose Tolerance Test (GTT) in transition dairy cows and clarify the metabolic characteristics of various physiological states from late gestation to early lactation. GTT was conducted at day prior to expected date of parturition (phase I) and 5 and 30 days after parturition (phases II and III), using five multiparous Holstein-Friesian cows. The levels of glucose at phases I and II sharply increased and then gradually decreased after infusion but the level at phase II was still higher than the basal value at 30 min post-infusion. The level of glucose at phase III 30 min post-infusion was kept at 1.3 times basal level at the end of GTT. Plasma insulin levels at phase I sharply increased at 15 min and immediately decreased after 30 min post-infusion. At phase II, the decline of insulin after 15 min post-infusion was gradual while levels at 120 min were still higher than the basal one. After 15 min, the rise of insulin at phase III was lower than those observed in others. The clearance rate of plasma insulin at phase I was twice as high as those at phases II and III. These findings suggested that these differences were caused by low insulin sensitivity due to onset of lactation and these changes were necessary for high producing dairy cows to maintain glucose homeostasis in early lactation.
Hiromi Terao, Masanori Fujita, Akemi Tsumagari, Toshihisa Sugino and Takashi Bungo, 2010. Insulin Dynamics in Transition Dairy Cows as Revealed by Intravenous Glucose Tolerance Testing. Journal of Animal and Veterinary Advances, 9: 2333-2337.