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Effect of light programs on the spontaneous fattening of goose liver without overfeeding
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International audience. We have already obtained spontaneous liver steatosis under experimental conditions in Greylag geese without force feeding. Hyperphagia was induced by combining a feed restriction period before ad libitum corn feeding, with an artificial reduction of day length. In the present work, the effect of the light program on the extent of hyperphagia and liver steatosis was investigated. 400 male geese had free access to a standard growth diet from birth (d0) to the age of 105 days (d105). Food access was then restricted to 1h/d until d132. Corn was provided ad libitum from d133 to d217. The birds had access to an outdoor area and were kept under a natural light cycle during the first 15 weeks. Then, this access was interrupted and an artificial light cycle of 10hLight:14hDark (10hL:14hD) was set up until d119. Three light programs were then tested from d120 to d217: kept as 10hL:14hD (group A); 10hL: 14hD until d147 and a light reduction of 30 min every 2 days until 7hL:17hD from d161 to d217 (group B); 10hL:14hD until d119 and a light reduction of 30 min every 2 days until 7hL:17hD from d133 to d217 (group C). The feed intake during the first week of ad libitum corn feeding (d133 to d140) was significantly higher in group C than in the two other groups (436g/d/bird vs 343 and 330 in groups A and B, respectively; P<0.05) but over the whole period (d133-d217), there were no significant differences between treatments for total corn consumption (244g/d/bird on average; NS). At d217, the liver weight, which was closely related to liver lipid content, was significantly (P<0.05) higher in birds from group C (321 g) than in birds from group A (248 g), birds from group B showing intermediate values (284 g). Overall, the variability in liver weight was high (CV > 60%). The present data confirm that hyperphagia and related liver steatosis are enhanced by a reduction of day length. This effect is maximized when the shortest light duration and the corn delivery start at the same time.
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