Activation of hepatic microsomal mixed function oxidase system in broiler chicks by diet changes

Two experiments were conducted to investigate the effect of diet composition on activity of the microsomal mixed function oxidase (MFO) system in broiler chicks. One-day-old chicks were fed for 10 days either a corn-soy (CS) diet or diets supplemented with a combination of fish meal, alfalfa meal, and torula yeast (FAY) or individually with fish meal (FM), alfalfa meal, distillers dried grains with solubles (DDGS), or torula yeast (TY). Activities of hepatic microsomal aniline hydroxylase and aminopyrine N-demethylase were increased when chicks were fed FAY, FM, TY, or DDGS compared with those fed CS. In another experiment chicks were fed the CS and FAY diets to 4 weeks of age. Hepatic microsomal cytochrome P-450, cytochrome b5, and activities of aniline hydroxylase and aminopyrine N-demethylase were significantly increased in birds fed the FAY diet. Activities of NADPH and NADH-cytochrome C reductase were not affected. These results show that the hepatic microsomal MFO system is activated by changes in diet composition and suggest that this activation may be responsible for reducing estradiol and liver lipid levels when similar diets are fed to laying hens.