**Background:** Duck eggs contain higher levels of cholesterol and fat than chicken eggs, raising health concerns for consumers. Sea buckthorn extract (SBE) is rich in flavonoids, polysaccharides, and other bioactive compounds with known lipid-lowering, antioxidant, and immunomodulatory properties. However, few studies have examined SBE effects in laying ducks, particularly regarding egg amino acid and fatty acid profiles. This study hypothesized that dietary SBE could improve production performance, egg quality, and reduce cholesterol deposition in Guangxi small hemp ducks.
**Methods:** Two hundred and forty 23-week-old laying ducks (BW 1,250 ± 60 g) were randomly divided into four groups with six replicates of 10 ducks each. Groups received a basal diet supplemented with 0 (control), 0.5, 1.0, or 1.5 g/kg SBE for 70 days following a 14-day adaptation period. The SBE contained 286.23 mg/g flavonoids, 103.79 mg/g quercetin, 23.66 mg/g kaempferol, and 20.18% sea buckthorn polysaccharide (purity 40.31%). Production performance was recorded throughout. On day 70, blood samples were collected from 12 ducks per group for serum biochemical analysis (TC, TG, HDL-C, LDL-C, SOD, T-AOC, MDA, GSH-Px, IgG, IgA, IgM). On day 69, 18 eggs per group were assessed for egg quality and yolk cholesterol. On day 70, 18 eggs per group were analyzed for amino acids (automatic amino acid analyzer) and fatty acids (gas chromatography). Statistical analysis used one-way ANOVA with Duncan's multiple comparison test (SPSS 25; P < 0.05 significant).
**Key Results:** Production performance: The 1.0 g/kg SBE group showed significantly increased average egg weight (64.110 g vs 61.891 g control; P = 0.033) and improved feed conversion ratio (2.501 vs 2.718 control; P = 0.044). No significant differences were found in ADFI or laying rate. Serum biochemistry: TC and TG were significantly reduced in 1.0 and 1.5 g/kg SBE groups (TC: 3.235 and 3.301 vs 4.074 mmol/L control; P = 0.014; TG: 2.161 and 2.762 vs 4.040 mmol/L control; P = 0.019). LDL-C was significantly reduced in the 1.5 g/kg group (3.787 vs 5.824 mmol/L control; P = 0.001). SOD and GSH-Px increased significantly in SBE groups (P < 0.05). T-AOC was highest in 1.0 and 1.5 g/kg groups (3.679 and 3.402 vs 2.282 U/mL control; P = 0.002). IgG, IgA, and IgM were highest in the 0.5 g/kg group (P < 0.001). Egg quality: Yolk cholesterol was significantly reduced in 1.0 and 1.5 g/kg groups (0.416 and 0.444 vs 0.516 mmol/gprot control; P = 0.026). Eggshell strength increased in the 0.5 g/kg group (53.419 vs 45.517 kgf/cm² control; P = 0.037). Albumen height and Haugh unit were highest in the 1.5 g/kg group (6.867 mm and 80.571 vs 6.293 mm and 75.993 control; P = 0.036 and 0.041). Amino acids: Total amino acids, essential amino acids, and umami amino acids significantly increased with SBE (P < 0.05). Fatty acids: Total MUFA increased significantly in all SBE groups (P = 0.003). DHA content increased 2.4-fold in 1.0 and 1.5 g/kg groups (0.089% and 0.090% vs 0.037% control; P < 0.001). Total SFA, PUFA, n-3 PUFA, and n-6 PUFA decreased with SBE (P < 0.05).
**Clinical Implications:** This study provides evidence that SBE at 1.0 g/kg can serve as an effective functional feed additive for laying ducks, improving egg weight, feed efficiency, and egg nutritional quality while reducing cholesterol content. The 2.4-fold increase in DHA content is particularly notable given DHA's role in preventing cardiovascular disease. The lipid-lowering effects (reduced TC, TG, LDL-C) and enhanced antioxidant capacity (increased SOD, GSH-Px, T-AOC) and immunity (increased immunoglobulins) suggest SBE could reduce the need for antibiotic feed additives. However, the study also indicates that excessive SBE (1.5 g/kg) may diminish some benefits, including reduced immunoglobulin levels and decreased eggshell strength, likely due to flavonoid-mediated inhibition of estrogen synthesis at higher doses. These findings support SBE as a natural alternative to antibiotics in poultry production, though optimal dosing requires careful calibration.