ed ▁it ▁centuries ▁later , ▁but ▁the ▁medieval ▁French ▁pe asant ' s ▁food ▁animals ▁were ▁mainly ▁p ig ▁and ▁sheep . ▁O thers ▁claim ▁that ▁the ▁tradition ▁was ▁preserved ▁by ▁the ▁Jews , ▁who ▁learned ▁the ▁method ▁of ▁en larg ing ▁a ▁go ose ' s ▁li ver ▁during ▁the ▁Roman ▁colon isation ▁of ▁J ude a ▁or ▁earlier ▁from ▁Egypt ians . ▁The ▁Jews ▁carried ▁this ▁cul inary ▁knowledge ▁as ▁they ▁migr ated ▁farther ▁north ▁and ▁west ▁to ▁Europe . ▁ ▁The ▁J uda ic ▁di et ary ▁law , ▁Kas hr ut , ▁forb ade ▁l ard ▁as ▁a ▁cook ing ▁medium , ▁and ▁but ter , ▁too , ▁was ▁pro scri bed ▁as ▁an ▁alternative ▁since ▁Kas hr ut ▁also ▁prohib ited ▁mixing ▁meat ▁and ▁da iry ▁products . ▁Jewish ▁cu is ine ▁used ▁o live ▁oil ▁in ▁the ▁Mediter rane an , ▁and ▁ses ame ▁oil ▁in ▁Bab yl onia , ▁but ▁neither ▁cook ing ▁medium ▁was ▁readily ▁available ▁in ▁Western ▁and ▁Central ▁Europe , ▁so ▁p oul try ▁fat ▁( known ▁in ▁Y idd ish ▁as ▁sch m alt z ), ▁which ▁could ▁be ▁abund antly ▁produced ▁by ▁over feed ing ▁ge ese , ▁was ▁subst it uted ▁in ▁their ▁stead . ▁The ▁del icate ▁taste ▁of ▁the ▁go ose ' s ▁li ver ▁was ▁soon ▁appreciated ; ▁Hans ▁Wilhelm ▁Kirch hof ▁of ▁K ass el ▁wrote ▁in ▁ 1 5 6 2 ▁that ▁the ▁Jews ▁raise ▁fat ▁ge ese ▁and ▁particularly ▁love ▁their ▁li vers .