Optimal dietary nano-VD₃ enhances growth performance and bone development in broilers through remodeling the gut microbiome and metabolites
摘要
Skeletal maldevelopment is a significant challenge in broiler production, causing substantial economic losses. Vitamin D₃ (VD₃) plays a critical role in poultry skeletal health, but its optimal dietary inclusion level for medium-growth broilers remains to be determined due to bioavailability differences among forms. This study investigated the effects of dietary VD₃ levels (conventional vs. nano-formulated) on growth performance, bone development, and gut microbiota composition and metabolite profile in broilers. A total of 420 one-day-old male Luhua broilers were randomly assigned to four groups in an 84-day experiment: a control group fed a basal diet, and three treatment groups supplemented with 3,750 IU/kg conventional VD₃ (CVD), 2,500 IU/kg low-dose nano-VD3 (LNVD), or 3,750 IU/kg high-dose nano-VD3 (HNVD).
ResultsBoth CVD and LNVD significantly enhanced average daily gain (ADG) and bone development by improving bone mineral content (BMC) and bone mineral density (BMD), mechanical properties (yield strength, stiffness, Elastic modulus), increasing calcium and ash content, and upregulating osteogenic gene expression (ALP, OC, OPG, BMP1) in the femur and tibia. Compared to CVD, LNVD led to significantly higher ADG from days 1–84 and greater bone indices at days 28, 56 and 84, including fresh bone weight (FBW), fat-free dry weight (FFDW), yield strength, elastic modulus, and calcium and ash content in the femur and tibia. In contrast, HNVD significantly decreased ADG and bone indices. Furthermore, cecal microbiome and metabolomics analysis showed that LNVD increased the relative abundance of beneficial bacteria (e.g., Ligilactobacillus, Muribaculaceae, NK4A214_group) and key metabolites (e.g., butyric acid, kynurenic acid, glutathione), while reducing harmful taxa (e.g., Desulfovibrio, Campylobacter_jejuni) and detrimental metabolites (e.g., leukotriene E3, 4-hydroxy-2-nonenal-Cys-Gly conjugate). These shifts significantly correlated with improved growth and bone traits.
ConclusionsIn summary, 2,500 IU/kg nano-VD₃ is recommended as the optimal supplementation level for Luhua broilers under the conditions of this study, offering a strategy to enhance VD₃ nutrition and skeletal health.