Evaluation of medicinal quality of tree peony byproducts and the effects of dietary byproducts supplementation on production performance, egg quality, serum antioxidant levels, and gut microbiota in late-phase laying hens.

Tree peony (Paeonia suffruticosa Andr.) is a resource plant native to China, valued for its ornamental, medicinal, and edible uses. It has abundant germplasm resources, with stems and leaves high in paeoniflorin and other medicinal ingredients that exhibit antimicrobial, anti-inflammatory and immune-boosting properties. This indicates its potential to replace antibiotics and promote healthy growth of livestock and poultry. This study aimed to clarify the medicinal and antibiotic replacement potential of tree peony stems and leaves. Our results showed that a total of 22 metabolites were detected in the stems and leaves, and 18 high-quality cultivars were screened. The optimal harvesting period was from 40 to 80 days after flowering. Dietary supplementation with tree peony stems and leaves significantly benefited late-phase laying hens by reducing the occurrence of broken and soft eggs and cholesterol content, while enhancing eggshell thickness and proportion, and increasing polyunsaturated fatty acids within the yolk. Furthermore, 16S rRNA sequencing analysis revealed that the supplementation enhanced cecal microbiota species diversity and increased Firmicutes and Lactobacillus abundance, resulting in significant alterations in microbial metabolic functions. Correlation analyses indicated these shifts positively influenced egg quality. Overall, tree peony stems and leaves offer a natural and efficacious alternative to probiotics or prebiotics, positively impacting laying hen production, egg quality, and health.