Poultry
In some countries, geese and ducks are force-fed to produce livers with an exceptionally high fat content for the production of "foie gras". Over 75% of world production of this product occurs in France, with lesser industries in Hungary and Bulgaria and a growing production in China. "Foie gras" is considered a luxury in many parts of the world, but the process of feeding the birds in this way is banned in many countries on animal welfare grounds.
Foie gras
Whole foie gras is readily available from gourmet retailers in Canada, the United States, Hungary, Argentina and regions with a sizeable market for the product. In US, raw foie gras is classified as Grade A, B or C. Grade A is typically the highest in fat and especially suited for low-temperature preparation, because the veins are relatively few and the resulting terrine will be more aesthetically appealing because it displays little blood. Grade B is accepted for higher temperature preparation, because the higher proportion of protein gives the liver more structure after being seared. Grade C livers are generally reserved for making sauces as well as other preparations where a higher proportion of blood-filled veins will not impair the appearance of the dish.