Time course study of liver lipid, mixed-function oxidase, and estradiol metabolism in laying hens fed different diets

The purpose of this investigation was to determine if hepatic mixed-function oxidase (MFO) activity, plasma estradiol, and estradiol metabolism changed in concert with liver lipid content when laying hens were fed two diets of different composition. White Leghorn laying hens were fed either a corn-soybean meal (CS) diet or CS plus fish meal, alfalfa meal, and torula yeast (FAY) for 24 days. Hens were sampled at the start of the experiment and at 4, 24, 10, 17, and 24 days after the dietary changes. By Day 17, liver weight per unit of body weight and liver lipid content were significantly lower for hens fed the FAY diet at 4 days, but a reversal occurred at later times and estradiol concentration tended to be higher for birds fed the CS diet for the remainder of the experiment. An in vitro estimate of the estradiol metabolism in the liver showed that by Day 17 the quantity of radioactive estradiol converted to water soluble metabolites was significantly increased in samples from hens fed the FAY diet. Feeding the FAY diet also significantly increased hepatic aminopyrine demethylation and aniline hydroxylation at Day 24.