Plasma Insulin Concentrations in Parturient Cows

Plasma insulin and glucose concentrations were higher prepartum (2 to 21 days) than postpartum in Jersey cows. Highest prepartum concentrations were in cows that later developed hypocalcemia. Hypocalcemic cows showed low plasma insulin concentrations and high plasma glucose concentrations. Plasma insulin increased and plasma glucose decreased after calcium borogluconate infusion in hypocalcemic but not in normal animals. These results further define the altered hormonal state of parturient dairy cows and support previous in vivo and in vitro observations that physiologic concentrations of calcium are required for glucose stimulation of insulin secretion.