Effect of Estrogen Implants on Hepatic Lipid Deposition in Chicks Fed Different Isonitrogenous and Isocaloric Diets

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Abstract
Two experiments were conducted to determine if differences in response of livers to estradiol administration in male broiler chicks would be observed if fed isonitrogenous and isocaloric diets of different composition. A polymethylsiloxane tube filled with estradiol dipropionate was implanted under the neck skin to ensure a constant release of hormone. Different tube sizes were implanted in two- or three-week-old chicks fed a basal corn-soybean meal (CS) diet or a diet containing fish meal, alfalfa meal, and torula yeast (FAY) or distiller's dried grains with solubles (DDGS). Body weight gains were significantly reduced by the highest level of estradiol in chicks fed the CS diet but not in chicks fed FAY or DDGS. Liver weight, deposition of lipid in liver and plasma lipid were markedly increased in proportion to the size of estradiol tube in chicks fed all diets. Increase of liver weight and lipid deposition by the highest level of estradiol in chicks fed the CS diet was significantly greater than that in chicks fed the FAY diet. Liver weight and the liver lipid response to estradiol in chicks fed the CS diet were significantly greater than that in chicks fed the FAY diet when dose response equations were compared among diets. These data show that the response on deposition of lipid in liver to estrogen administration was modified by the type of ingredients included in diets with similar energy and nutrient profiles.