This study aimed to investigate the temporal dynamics of physiological and gut microbial responses in Mule ducks (M-D) during force-feeding (F-F), with the goal of identifying potential regulatory targets to reduce feeding stress. Male M-Ds were subjected to either F-F or ad libitum feeding. We conducted longitudinal analysis at 72, 78, and 84 days of age to assess growth performance, serum biochemical profiles, and intestinal inflammatory markers, while assessing gut microbiota composition through 16S rDNA sequencing. The F-F group exhibited superior growth performance. Initial physiological responses at day 72 included significantly reduced serum corticotropin-releasing hormone (CRH) and jejunal tumor necrosis factor-alpha (TNF−α). Conversely, F-F induced a persistent and profound alteration in the gut microbiome by day 84, characterized by reduced alpha diversity and a significant enrichment of the genus Limosilactobacillus. Correlation analysis identified Limosilactobacillus as a keystone taxon, strongly associated with intestinal metabolites. Our findings demonstrate that M-Ds undergo time-dependent metabolic and immunological adaptations in response to F-F stress, which correlates with distinct alterations in gut microbiota composition, particularly the enrichment of Limosilactobacillus. These findings provide a theoretical basis for developing microbiota-targeted strategies to alleviate F-F stress in foie gras production.

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.