Effects of overfeeding on lipid synthesis, transport and storage in two breeds of geese differing in their capacity for fatty liver production

Lipid synthesis, transport, and storage were investigated in two genotypes of geese that differ in their response to overfeeding, i.e. the Landes goose, which is highly susceptible to hepatic steatosis, and the Poland goose, which is partly resistant. In control, non overfed geese of the two breeds, lipid metabolism did not differ markedly. In the liver and two adipose tissues (abdominal and subcutaneous), the lipogenic capacity, in terms of fatty acid synthesis (acetyl-CoA carboxylase and fatty acid synthase) and NADPH providing ( malic enzyme and glucose-6-phopshate dehydrogenase), was very similar, as was the concentration and composition of very low density (VLDL) and high density (HDL) lipoproteins, which are plasma lipoproteins responsible for the transport of lipids from the liver towards the adipose tissue. In consequence, the lipid storage, expressed as a relative proportion and lipid content of the liver and the two adipose tissues was identical in both breeds. Therefore, under our experimental conditions, it was not possible to find any metabolic markers of lipid metabolism that could be considered a limiting factor of the further capacity for fatty liver in the overfed Poland goose. By contrast, overfeeding resulted in a dramatic enhancement of lipid synthesis (liver and adipose tissue lipogenesis), transport (VLDL and HDL concentration) and storage ( relative weight and lipid content of the liver and adipose tissues). Besides, and despite food intake during overfeeding being similar in both breeds, hepatic lipogenesis was higher in the Landes goose, but did not result in a higher triglycerides (TG) concentration in plasma and VLDL. This suggests that the capacity of TG secretion remains identical in both breeds, and would explain why hepatic TG storage is so efficient in the Landes goose.