Natural induction of spontaneous liver steatosis in Greylag Landaise geese (Anser anser).

The present experiment aimed at demonstrating that the Greylag geese (Anser anser), commonly used for the production of foie gras, are able to develop spontaneous hyperphagia and subsequent liver steatosis under specific handling conditions and without over-feeding. One hundred and eighty male geese were used in this experiment. After a period of feed restriction, at the age of 19 wk, corn was provided ad libitum. From wk 21 to 23, the daylight duration was progressively reduced from 10 to 7 h and kept as such until the end of the experiment (wk 31). Thirty birds were slaughtered at wk 19, 23, 25, 27, 29, and 31. During the first 2 wk after corn delivery, the average consumption rose up to 600 g/bird/d and decreased slowly thereafter to reach 270 g at wk 31. The liver weight increased from 95 (wk 19) to 514 g (wk 31), and most of these changes were due to the increase in liver lipid content from 6 to 50% of liver weight. There was no mortality during the experimental period. Histological observations indicate that the accumulation of fat in the livers occurred through a large increase in the size of the hepatocytes without modification of the cell boundaries and without any sign of inflammation or degeneration. Our data clearly show that under specific management conditions of feeding and photoperiod, the geese are able to initiate spontaneous liver steatosis. These results demonstrate their natural ability to store fat in the liver without any visible sign of tissue alteration. However, the variability in the response remains very high (at wk 31, the CV in liver weight was 45%). Further research is needed to better understand the origin of this variability.