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
Fattened liver can be produced by alternative methods without gavage, and this is often referred to either as "fatty goose liver" or as foie gras (outside France), though it does not conform to the French legal definition. This method involves timing the slaughter to coincide with the winter migration, when livers are naturally fattened.
The winner of the Coup de Coeur award at the Salon International d'Alimentation, SIAL 2006, Patería de Sousa produces fattened livers without force-feeding. This has only recently been produced commercially, and is a very small fraction of the market.