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
After the fall of the Roman empire, goose liver temporarily vanished from European cuisine. Some claim that Gallic farmers preserved the foie gras tradition until the rest of Europe rediscovered it centuries later, but the medieval French peasant's food animals were mainly pig and sheep. Others claim that the tradition was preserved by the Jews, who learned the method of enlarging a goose's liver during the Roman colonisation of Judea or earlier from Egyptians. The Jews carried this culinary knowledge as they migrated farther north and west to Europe.