Effects of Force-Feeding on Liver Lipid Accumulation and Fatty Acid Profiles in Mule Ducks

This study characterized lipid accumulation in force-fed mule duck foie gras (fatty liver) and evaluated its association with hepatic physiological status. Thirty-six healthy male mule ducks (67 ± 2 days of age) were randomly assigned to a control group (CON) or force-fed group (O-F). Serum and liver samples were collected for further analysis on days 6, 12, and 18. Compared with the CON group, force-feeding markedly increased liver weight on days 6, 12, and 18, with average increases of 100 g, 200 g, and 430 g, respectively (p < 0.01). No significant differences were observed in hepatic oxidative stress markers, inflammatory cytokines, and biochemical indicators of liver injury on days 6, 12, and 18 between the control and force-fed groups (p > 0.05). Furthermore, both untargeted lipidomic Orthogonal Partial Least Squares—Discriminant Analysis (OPLS-DA) and targeted fatty acid analysis revealed clear metabolic separation between the two groups on day 18. Compared with CON, total hepatic unsaturated fatty acids increased by 60.7% in O-F ducks on day 18 (p < 0.01), with oleic acid, linoleic acid, α-linolenic acid, and eicosapentaenoic acid increasing by approximately 400%, 100%, 300%, and 35%, respectively (p < 0.01). These results indicate that short-term force-feeding alters the hepatic fatty acid profile through lipid accumulation, while circulating markers of liver injury remain unaffected.