Insulin Response to Amino Acid and Glucose Intravenous Infusions in Dairy Cows: Synergistic Effect

The effect of 30 minute intravenous infusions of amino acids (90 or 180 g) or glucose (114 g or 228 g) was studied in five non-pregnant lactating dairy cows. At each dose the same amounts of energy were delivered by glucose or amino acids. The nutrients were infused separately or in combination. In response to each nutrient, plasma insulin increased proportionally to the dose infused. The increase induced by amino acids was lower than that induced by glucose, and plasma insulin returned to its baseline value more rapidly after amino acid than after glucose infusion. The hypoglycemia that developed after amino acid infusions partly explains the short-lived amino acid induced in insulin response. The plasma insulin increase which resulted from the glucose-amino acid mix significantly exceeded that obtained by separate but isocaloric infusions of amino acids or glucose. Therefore, amino acids and glucose acted synergistically to increase plasma insulin release. The mechanism leading to the synergistic effect would be partially due to a permissive effect of hyperglycemia. Other possible potentiating mechanisms are discussed.

Key words

Dairy Cows - Plasma Insulin - Amino Acids - Glucose - Synergism