miniature swine have been studied using surgically implanted cannulae in the duodenum and ileum and catheters in the aorta, portal vein, cisterna chyli, hepatic vein and posterior vena cava. Gut and liver have been shown to have different substrate characteristics for cholesterol synthesis and different die-away curves for cholesterol. Bile acids have been found in tissues and gut bile acid die-away has been measured. These measurements are now being made on minipigs fed diets containing 40 percent of calories as beef fat (SFA) or safflower oil (PUFA).