Effect of intraperitoneal administration of amino acids on the food intake of piglets on a liquid diet during the first month after birth

The effect of single intraperitoneal 1 g.kg-1 doses of a solution of 20 amino acids (AA) on food intake was investigated in 20 piglets examined repeatedly between 2 and 26 days of age. The animals were reared individually from day 1 after birth in cages and bottle-fed a liquid diet nine times per day at two-hour intervals from 6 to 22 h. Although amino acid administration did not significantly affect plasma concentrations of total free AA throughout the experiment (as measured just before and 2 and 5 h after AA administration in blood withdrawn from the external jugular vein) it did produce a downward trend in food intake of piglets at 9-10 d of age. In older animals, the depressive effect on food intake was significantly greater and lasted longer. It is suggested that the aminostatic component of food intake regulation in piglets does not begin to operate until the weaning period.