Cholesterol is essential to life activity,but dietary cholesterol abounding in eggs has been suggested to increase the risk of human cardiovascular diseases.In order to decrease the cholesterol in the yolk,the cholesterol metabolism of laying hens has been studied by nutritional and biochemical ways.There is no difference of cholesterol biosynthesis between mammalian and laying hens,but the transportation of cholesterol is evidently different between them.By far,the HMG-CoA reductase inhibitors have been pr...