Chemical composition and sensory qualities of fat livers obtained by force-feeding or by spontaneous fattening

The present experiment aimed at comparing fatty livers obtained from overfeeding or from an alternative method. Indeed, it has previously been shown that, under specific handling conditions and without overfeeding , it was possible to obtain in Greylag geese (Anser anser) a spontaneous liver steatosis. The livers were compared for chemical and lipid composition, quality indicators, sensory traits and acceptability by consumers.Two hundred and thirty male geese were reared, but for practical reasons only ninety five livers were analyzed in this experiment. From hatching, geese were subdivided in three groups, and each group followed different rearing treatments. Eighty five birds followed a standard overfeeding method, one hundred and twenty five birds followed an alternative one, based on the simulation of premigratory period, and a third group of twenty birds was used as control.After treatment all animals were slaughtered, respectively at 17 (overfed), 31 (stimulated) an 19 weeks (control) of age. During the treatment there was an increase in body and liver weight, for both treatments groups as compared to control. The average values of liver weight were strongly higher in overfed birds (1102 g) than in the stimulated (445 g). Lipid analysis shows that overfed birds’ livers have higher lipid content (56%) than stimulated livers (53%), whereas free glucose and glycogen are higher in stimulated birds’ livers. Neutral lipid profile, obtained by Gas Chromatography (GC), showed some differences between the two groups, mainly in term of diglycerides and cholesterol esters. Sensory analysis indicated that fatty livers obtained under standard overfeeding conditions were globally more appreciated than those obtained by stimulation.Results for an alternative production of fatty liver are encouraging, however the variability in the individual response remains very high. Further research is needed to better understand the origin of this variability.