Effects of Astragalus membranaceus fiber on growth performance, nutrient digestibility, microbial composition, VFA production, gut pH, and immunity of weaned pigs

Astragalus membranaceus is an herbaceous perennial plant, growing to about 2 feet tall, with sprawling stems and alternate leaves about 12-24 leaflets. In total, 24 cross bred (Duroc x Landrace x Yorkshire) piglets weaned at 4 weeks with an average body weight of 10.84 +/- 1.86 kg, were divided into four groups and randomly assigned to dietary treatments containing different AMSLF levels (0.00%, 2.50%, 5.00%, and 7.50%). The piglets in the control group (0.00% AMSLF) were fed basal diet and other treatment groups were fed basal diet in addition to 2.50%, 5.00%, and 7.50% pulverized AMSLF. The results indicated that supplementation with AMSLF significantly (p < 0.05) decreased diarrheal incidence in piglets. There was significant difference between treatment in terms of ADFI, ADG and FCR. Both 5.00% and 7.50% treatments significantly increased growth performance. The digestibility of gross energy and dry matter increased (p > 0.05) with increasing AMSLF level. The level of blood IL-2 and TNF-alpha were significantly affected by AMSLF supplementation with 7.50% AMSLF group having higher (p < 0.05) IL-2 and TNF-alpha levels than the other treatment groups. The 16SrDNA sequencing results from the four treatments showed that the potentially active bacterial microbial population and diversity in pig cecum were dominated by the phyla Bacteriodetes and Firmicutes regardless of the AMSLF supplementation. The Shannon diversity, PD whole tree diversity indices and Chao analyses exhibited significant variability in species richness across the treatments. The principal coordinates analysis (PCoA) showed significant (p < 0.1) differences between bacterial communities in all treatment groups. Results from the current study suggested that AMSLF supplementation increased composition of bacterial microbiota in pig gut. In conclusion, dietary supplements with AMSLF could potentially be used to prevent diarrheal incidence and improved pig production.