Chicken hepatic metabolism in vitro. Protein and energy relations in the broiler chicken--VI. Effect of dietary protein and energy restrictions on in vitro carbohydrate and lipid metabolism and metabolic hormone profiles.

1. Ross male broiler chicks growing from 14 to 28 days of age were fed 14 and 20% protein diets (4 kcal day-1/body wt0.66) or 20 and 28% protein diets (2.8 kcal day-1/body wt0.66) in a 2 x 2 factorial arrangement to determine the effects of protein and energy intakes on in vitro lipogenesis (IVL) and net glucose production (NGP). Plasma concentrations of insulin, glucagon, thyroid hormones (T3 and T4) and somatomedin-C (Sm-C) were estimated by radioimmunoassay. 2. There was a significant (P less than 0.05) decrease in IVL in the chicks given the higher daily protein intake. 3. The higher protein intake increased (P less than 0.05) NGP while the lower energy intake decreased (P less than 0.05) NGP. 4. Insulin, both thyroid hormones and Sm-C were affected by dietary energy and protein intakes.