Modified Shen Ling Bai Zhu San Combined with Its Essential Oil Regulates Growth Performance, Lipid Metabolism and Intestinal Health in Silky Fowls

Background: Antibiotic exposure disrupts gut microbiota and lipid metabolism, hindering healthy poultry farming, especially for medicinal Silky fowls. Given that essential oils are prone to volatilization during the decoction of traditional Chinese medicine, this study evaluated modified Shen Ling Bai Zhu San and its essential oils (SLEO) on growth, lipid metabolism, and intestinal health in Silky fowls. Methods: 540 Silky fowls were divided into CON, ATB, ATB+SLEO, and SLEO groups. The cecal microbiota was analyzed via 16S rRNA sequencing. Results: ATB improved weight gain but increased abdominal fat, liver lipid accumulation, and serum triglycerides/cholesterol. Lipid transporter and metabolism gene expression was upregulated, while CPT1A and PPARα were downregulated. SLEO alone significantly improved intestinal villus morphology, as evidenced by a higher villus height/crypt depth (V/C) ratio compared to the ATB group (p < 0.05), along with reduced mortality and enhanced barrier gene expression, without adverse lipid effects. Antibiotics reduced cecal microbial α/β diversity, which SLEO reversed. Enriched SLEO-associated strains correlated strongly with lipid metabolism. Conclusion: SLEO may serve as an antibiotic alternative, regulating lipid metabolism, reducing fat deposition, maintaining gut microbiota homeostasis, and alleviating antibiotic-induced adverse effects.