Effect of propionate infusion on plasma glucagon, insulin and growth hormone concentrations in lactating dairy cows

Altered concentrations of metabolic hormones have been suggested as important mediators of energy partitioning during early lactation. This study was initiated to determine the effects of propionate (1.0 mmol/kg body weight) infusion on plasma concentrations of glucagon, insulin, growth hormone, propionate and glucose at 14 days ante-partum (AP) and days 5 and 30 postpartum (PP). No differences were seen in propionate concentrations between sampling days. Glucose concentrations were elevated following propionate infusion in pregnant cows but were not elevated in the PP cows. Insulin responses to propionate infusion did not differ between days while the glucagon response was blunted at day 5 PP. Basal glucagon concentrations were elevated between days 5 and 30 PP, insulin concentrations were unchanged between days, while the molar insulin/glucagon ratio was decreased during early lactation. Basal growth hormone (GH) concentrations were elevated between day 14 AP and day 30 PP. GH responsiveness to declining propionate concentrations was greatest at day 5 PP. These data further suggest a role for glucagon as well as GH in nutrient partitioning during early lactation.