Gastric inhibitory polypeptide concentrations in lambs fed milk or milk constituents

Gastric inhibitory polypeptide (GIP) concentrations were determined in plasma obtained from lambs before and after feeding milk or milk constituents. Plasma GIP increased after feeding whole milk or cream but was unchanged after the skimmed milk or lactose solution meal. Serum insulin concentrations increased after whole or skimmed milk or lactose solution was fed but were unchanged after the cream meal. Changes in plasma GIP concentrations correlated with changes in plasma triglycerides but not with plasma glucose or serum insulin. Triglyceride but not glucose absorption appears to be the stimulus for GIP secretion in lambs, and GIP does not appear to augment the glucose-induced secretion of insulin.