You can buy it in every grocery shop months before Christmas, a huge tradition, eaten in every possible way, more or less expensive depending on the brand and a must on every French holiday table.
'Foie gras', the pathological liver of a bird suffering from hepatic steatosis. Yes, you heard me correctly, 'Foie gras' is produced by force-feeding ducks or geese so as to enlarge their liver up to ten times its normal size. Force-feeding involves over-enlarging the liver by filling the animal's stomach with large quantities of corn over a twelve day period, using a tube called an ‘embuc’. Every year in France, 30 million ducks are force-fed in order to produce foie gras.
Where Are Animal Rights?
Considered incompatible with animal protection laws, the practice of force-feeding has already been banned in most European Union countries.
Animal rights organizations condemn this practice, judged harmful to the well-being of birds. They rightfully claim that "No animal shall be provided with food or liquid in a manner (…) which may cause unnecessary suffering or injury."Council Directive 98/58/EC of 20 July 1998.''
To counter their arguments, foie gras producers stand behind studies by the French National Institute for Agricultural Research (INRA). It just so happens that the studies in question are in part (up to 20%) financed by the Inter professional Committee for Foie Gras (Cifog).
Honey And Figs For Ducks
The practice of enlarging the liver is not new, Apicius, the chef of Roman emperor Tiberius, fed figs and wine mixed with honey to ducks and geese. History passionate, the chef Marcel Metzler is feeding his ducks the same way. He says that the ancient instinct of ducks forces them to eat more and thus their liver becomes enlarged naturally.
A society called Avivell, counts on using fermentation of the intestinal microbiota (announced to be put on the market in 2019). 
 Regal, nm.86, p.82.