The effects of supplementing Astragalus and fermented Astragalus on lactation performance, rumen microbiota, and lamb weight gain in Turpan black sheep

This trial selected Turpan Black ewes at 100 days of gestation as test subjects to investigate the effects of supplemental feeding with Astragalus and fermented Astragalus on the ewes' rumen microbial community structure, plasma metabolites, antioxidant capacity, milk composition, as well as the immune parameters and growth performance of newborn lambs, in order to provide a theoretical basis for stress alleviation and the application of Astragalus and fermented Astragalus. The trial selected 60 Turpan Black ewes at 100 days of gestation and randomly divided them into three groups: Control group (CON group): basal diet; Astragalus group (AM group): basal diet + 2 g/day·head of Astragalus; Fermented Astragalus group (FAM group): basal diet + 2 g/day·head of fermented Astragalus. Each group consisted of 20 ewes, with a 5-day adaptation period and a 90-day experimental period. Dietary supplementation with Astragalus increased milk yield ( p >0.05) and significantly enhanced antioxidant capacity, as evidenced by elevated catalase (CAT) activity and reduced nitric oxide (NO) levels ( p < 0.01). Metabolomic analysis revealed that the treatment upregulated picolinic acid and related metabolites, thereby activating the tryptophan metabolic pathway ( p < 0.01), which consequently improved rumen microbial community structure characterized by increased relative abundances of Bacteroidetes and Firmicutes . Additionally, membranaceus supplementation elevated birth weight of male lambs by 6.78%, and significantly increased serum concentrations of growth hormone (GH; p < 0.01), and immunoglobulins (IgA, IgG, and IgM; p < 0.01), accompanied by enhanced antioxidant capacity ( p < 0.01). Fermented Astragalus membranaceus supplementation increased milk yield and enhanced ewe lactation performance, evidenced by elevated lactose content ( p < 0.05). The intervention substantially improved systemic redox status, manifesting as increased T-AOC ( p < 0.01) and augmented antioxidant enzyme activities (elevated CAT, reduced NO and MDA, p < 0.01). Rumen microbial profiling revealed significant enrichment of Bacillales, Methanobacteriales , and Spirochaetales ( p < 0.05), coupled with metabolomic signatures indicating downregulation of medicarpin and concomitant activation of the α-linolenic acid metabolism pathway ( p < 0.01). In offspring, the treatment increased male lamb birth weight ( p < 0.01) and sustained elevation of GH secretion across all developmental stages ( p < 0.01). Immunologically, neonatal lambs exhibited significantly higher circulating IgA, IgG, and IgM concentrations ( p < 0.01), alongside enhanced neonatal antioxidant capacity characterized by elevated CAT and reduced NO levels ( p < 0.01). In summary, fermented Astragalus demonstrated superior intervention effects compared to raw Astragalus in improving ewe milk quality, enhancing antioxidant capacity, optimizing rumen microbial flora structure, regulating lipid metabolism pathways, and promoting lamb growth, immunity, and antioxidant development.