Regulation of glucose metabolism in dairy cattle.

摘要

The experiments described herein are designed to elucidate many metabolic changes that occur to regulate the partitioning of nutrients between production and animal maintenance with particular regard to glucose metabolism and insulin sensitivity. The onset of milk production and parturition causes dramatic stress to the cow. The challenge of improving metabolism during this period is being addressed by nutritional management with the possibility of the addition of supplements. The use of Ca-propionate as a supplement did not affect glucose metabolism in transition cows. The data revealed that insulin sensitivity was low during the transition period, but the tissue responses to insulin and the acute insulin response to a glucose infusion increased slightly after calving as compared to late gestation. Glucagon and nonesterified fatty acid concentrations increased throughout the transition period, while glucose, insulin, and thyroxine concentrations decreased. A need for a relatively easy and inexpensive test for evaluating glucose metabolism has been indicated, and it was shown that the Minimal Model computer analysis of the frequently sampled glucose tolerance test was adequate in assessing insulin sensitivity in dairy cattle. The acute hyperinsulinemia induced by the insulin tolerance test or by the hyperinsulinemic euglycemic test did not affect plasma leptin concentrations.