ter ▁to ▁co inci de ▁with ▁the ▁winter ▁migration , ▁when ▁li vers ▁are ▁naturally ▁f atten ed . ▁ ▁The ▁winner ▁of ▁the ▁C oup ▁de ▁Co eur ▁award ▁at ▁the ▁Sal on ▁International ▁d ' Al iment ation , ▁SI AL ▁ 2 0 0 6 , ▁P ater ía ▁de ▁S ous a ▁produces ▁f atten ed ▁li vers ▁without ▁force - feed ing . ▁This ▁has ▁only ▁recently ▁been ▁produced ▁commer cially , ▁and ▁is ▁a ▁very ▁small ▁fraction ▁of ▁the ▁market . ▁ ▁Produ cers ▁outside ▁France ▁do ▁not ▁always ▁force - feed ▁birds ▁to ▁produce ▁f atten ed ▁li vers ▁considered ▁to ▁be ▁fo ie ▁gr as , ▁instead ▁allowing ▁them ▁to ▁eat ▁freely , ▁term ed ▁ad ▁li bit um . ▁Interest ▁in ▁alternative ▁production ▁methods ▁has ▁grown ▁recently ▁due ▁to ▁eth ical ▁concerns ▁in ▁g av age - based ▁fo ie ▁gr as ▁production . ▁Such ▁li vers ▁are ▁altern atively ▁term ed ▁fat ty ▁go ose ▁li ver , ▁eth ical ▁fo ie ▁gr as , ▁or ▁hum ane ▁fo ie ▁gr as . ▁ ▁The ▁British ▁super market ▁chain ▁Wait rose ▁also ▁provides ▁a ▁version ▁of ▁eth ical ▁fo ie ▁gr as ▁which ▁it ▁calls ▁( and ▁has ▁been ▁tra dem ark ed ) ▁f aux ▁gr as . ▁This ▁is ▁not ▁to ▁be ▁confused ▁with ▁the ▁American ▁product ▁by ▁the ▁same ▁name , ▁produced ▁by ▁Reg al ▁Veg an , ▁which ▁has ▁the ▁US ▁tra dem ark ▁for ▁f aux ▁gr as