Effect of subcutaneous and intraperitoneal administration of insulin on the milk intake of suckling lambs.

Intraperitoneal or subcutaneous injections of Neutral Zn-insulin (4 U/kg b.w.) were given to suckling lambs. Milk intake was significantly increased 8 h and 22 h after intraperitoneal insulin administration; the subcutaneous injection was ineffective. Insulin levels and serum glucose changes were similar in both experimental groups, but we observed significant decrease in total lipids /2 1/2 h, 5 1/2 h), a rise in serum triglycerides (7 3/4 h) and increased serum thyroxine levels (5 1/2 h, 7 3/4 h) after intraperitoneal insulin administration. It is assumed, that intraperitoneal (not subcutaneous) insulin evokes specific biological responses resulting in long lasting hyperphagy in suckling lambs.