EFFECTS OF OVERFEEDING OF PROTEIN AND ENERGY BY FORCE FEEDING ON HEPATIC-MICROSOMAL MIXED-FUNCTION OXIDASE SYSTEM IN BROILER-CHICKENS

Two experiments were undertaken to determine the effects of excess intake of protein and energy on hepatic microsomal mixed function oxidase (MFO) system in male broiler chickens. Two levels of protein (100 or 117% of ad libitum feeding) and energy (100 or 114% of ad libitum feeding) intake in factorial arrangements of treatments were used in experiment 1. Chicks (38 days of age) were provided the dietary treatments by tube-feeding for 8 days. In experiment 2, chicks were fed a control diet (23% protein and 3.2 Meal metabolizable energy/kg diet) or a high protein and high energy (32% protein and 3.4 Meal metabolizable energy/kg diet) ad libitum for 11 days. Energy intake over ad libitum feeding resulted in a reduction of cytochromes P-450 and b5 content. Excess-intake of protein did not overcome the reduction of the cytochromes by overfeeding of energy. Feeding high protein diet with high energy content resulted in a reduction of the MFO system in the liver compared with feeding a control diet in the ad libitum condition. The results suggest that energy intake in broilers is the predominate modifier of hepatic microsomal MFO rather than protein intake under overfeeding conditions.