Modulation of the feeding response of lactating dairy cows to peripheral insulin administration with or without a glucose supply

The aim of this study was to determine the effect of physiological amounts of insulin without glucoprivation on food intake of daily cows. Four multiparous Holstein cows at 150 days postpartum were allocated to the treatments, consisting of a 4 h intravenous infusion of: I)control (saline); 2) insulin (3.41 mu g/kg); 3) glucose (2.75 mmol/kg); and 4) insulin plus glucose (same dosage). A complete diet was offered ad libitum and the intake behaviour was continuously recorded. The plasma insulin was only slightly increased during the insulin treatment, but the treatments including glucose increased it more. The insulin treatment increased dry matter intake during infusion (+12%, P < 0.07), but the increase was offset during the following 4 h. In contrast, dry matter intake was slightly decreased by insulin during the first hour of infusion (-8%; P < 0.03) when the insulin-induced hypoglycemia was prevented by a concomitant infusion of glucose. The insulin-induced glucoprivation stimulated food intake, whereas glucose availability had no obvious satiating effect in dairy cows.