Influence of kinetics of gastric emptying on hepatic IGF1 production in young calves.

Five preruminant calves, fitted with chronically indwelling catheters in the hepatic and portal veins and hepatic artery, were fed two kinds of diet (a conventional clotting milk diet and an incurdled milk diet) or fasted for 24 h. The statistical analysis of the plasma growth hormone (GH; nmol/l) or IGF1 (nmol/l) daily secretory profiles indicated that hormonal levels were very high in fed calves (GH mean values: 0.40 +/- 0.11 and 0.36 +/- 0.10, respectively; IGF1 mean values: 6.65 +/- 0.57 and 7.54 +/- 0.33, respectively). The GH secretory profile observed over a 24-hour period showed 7 secretory spikes without periodicity in both diets. In fasting animals, plasma GH and IGF1 concentrations were very low (0.17 +/- 0.08 and 3.08 +/- 0.36, respectively) and stable, they increased with refeeding (1.51 +/- 0.05 and 7.36 +/- 0.55, respectively). Hepatic IGF1 production (micrograms/kg body weight/day) was 195 +/- 7 in standard milk fed calves and -255 +/- 30 in others. Our results demonstrated that nutritional factors, such as different kinetics of gastric emptying or fasting, may influence hepatic IGF1 production in the conscious newborn calf.