Hyperphagia and hepatic lipid storage in ducks: an exploratory experimental model

This study aimed to investigate whether spontaneous hyperphagic behavior can be induced in mule ducks through a protocol combining feed restriction followed by one-hour concentrated meals, and to assess the resulting hepatic metabolic responses. To achieve this, two protocols were tested. The first protocol initially demonstrated that a five-day acclimation phase, consisting of alternating 23-hour fasting periods and one-hour refeeding periods, was necessary to induce hyperphagia in ducks. Then, an increase in liver weight and glycogen content was measured up to 12 hours after the substantial meal, before returning to baseline after 24 hours, while total lipid levels remained unchanged. Based on these observations, a second protocol was designed to assess whether an additional meal provided 12 hours after the last substantial meal could promote lipid storage in the liver. A significant increase in liver weight and glycogen content was measured after each one-hour meal, while total hepatic lipid content increased significantly after the last meal provided 12 hours after the previous one. This was associated with an upregulation of genes involved in lipogenesis ( FASN, SCD1, ELOVL6) and carbohydrate oxidation ( HK1), and a downregulation of a gene involved in lipid oxidation ( ACSL1). Together, these results demonstrate for the first time that voluntary feeding alone can induce measurable hepatic lipid accumulation in mule ducks. This new protocol represents a valuable experimental model for the study of hepatic lipid metabolism in ducks and could contribute to the development of alternative strategies for liver fattening.