Spirulina (Arthrospira platensis) is rich in a variety of fermentable fibers and prebiotics, which can promote the proliferation of beneficial flora in the intestinal tract of ruminants and optimize the balance of microorganisms in the rumen. The aim of this study was to evaluate whether dietary supplementation with Spirulina has a beneficial effect on the rumen microbial community and serum indices in lambs. For this purpose, 36 lambs with a mean weight of 21.68 kg (standard deviation 1.04 kg) and an age of approximately 5 months (standard deviation 4 days) were selected for the study. The same scale was used for age standard deviation, i.e., 4 days/30.5 days (1 month) = 0.13 months. All lambs were randomly assigned into two treatments, and received non-Spirulina diet as the control (CK treatment) and the Spirulina added diet (Spirulina was added at a rate of 3% of the fresh weight of the diet). The results indicated that the triacylglycerol (p < 0.0001), alanine transaminase (ALT) (p < 0.0001), aspartate aminotransferase (AST) (p < 0.0001), glucose (p < 0.0001), immunoglobulin G (p = 0.0066) and insulin (p = 0.0025) levels were markedly increased in the Spirulina treatment compared to those in the CK treatment. The principal coordinates analysis showed that the bacterial community did not cluster separately between the CK and Spirulina treatments. Firmicutes, Bacteroidetes and Actinobacteria were the dominant members of the community in two treatments. Prevotella were the primary genera, followed by the Lachnospiraceae_NK3A20_group, Olsenella, Succinivibrionaceae_UCG-001 and Ruminococcus, and a significant (p < 0.05) difference was found in Olsenella between the two treatments. These results suggest that the addition of Spirulina is more beneficial for serum biochemical parameters and rumen microbiota of lambs. Overall, these findings contribute to the development of strategies to improve rumen microbial communities for healthy ecosystems on the Mongolian Plateau and provide a scientific basis for the use of Spirulina in feed.

Phycocyanin is a water-soluble pigment protein extracted from prokaryotes such as cyanobacteria and has strong antioxidant activity. As a silage additive, it is expected to enhance the antioxidant activity and fermentation quality of alfalfa silage. This study revealed the effects of different proportions of phycocyanin (1%, 3%, 5%) on the quality, bacterial community and antioxidant capacity of alfalfa silage. The results showed that 5% phycocyanin supplementation could maintain dry matter (DM), crude protein (CP) and water-soluble carbohydrate (WSC) content; increase lactic acid (LA) content; decrease pH and butyric acid (BA) and ammonia nitrogen (NH₃-N) content; and improve fermentation quality. At the same time, the contents of total antioxidant capacity (TAOC), total phenol content (TP), polysaccharide content (P) and total flavonoid content (F) in the addition group were significantly increased, the antioxidant capacity was enhanced and the abundance of lactic acid bacteria was increased, which was positively correlated with silage quality. Phycocyanin can improve the metabolic function of carbohydrates and amino acids and promote the production of secondary metabolites. The application of phycocyanin broadens the variety of additives for alfalfa silage.

Fermented total mixed ration (FTMR) is an effective approach to preserve low-quality crop residues. This study investigated the effects of ensiling duration (0, 3, 5, 7, 15 and 30 days) on nutritional dynamics, fermentation quality, in vitro digestibility, and bacterial communities of FTMR containing corn stalk and broom sorghum straw at 50% moisture. After 30 d of ensiling, FTMR had the highest crude protein content, lowest neutral detergent fiber content, peak lactic acid concentration, stable low pH, undetectable butyric acid, and maximum in vitro NDF digestibility. Bacterial alpha diversity declined significantly during ensiling, and the community was dominated by Leuconostoc, Lactiplantibacillus, and Levilactobacillus. These results clarify the microbial regulatory mechanism of mixed-straw FTMR fermentation and support the efficient utilization of crop residues in ruminant production.

Spirulina (Limnospira platensis) has gained attention as a functional feed additive in animal nutrition. However, its effects on the cecal microbiota and systemic metabolic responses in lambs remain unclear. Here, twelve 5-month-old male Hu lambs were randomly assigned to a control group (Control) or a Spirulina-supplemented group (SPI; 1.5% of dietary dry matter) and fed for 60 days (n = 6 per group). We measured serum biochemical indices, energy-metabolism variables, and immune and antioxidant parameters and characterized the cecal microbiota using 16S rRNA gene sequencing. Spirulina supplementation increased serum triglycerides (TG), glucose (GLU), alanine aminotransferase (ALT), and aspartate aminotransferase (AST) (p < 0.05). In the cecum, α-diversity indices were lower in SPI than in Control (p < 0.01), and Principal Coordinates Analysis (PCoA) indicated distinct community separation between groups (p < 0.01). Spearman correlation analyses further linked dominant genera to host metabolic and antioxidant traits. Collectively, Spirulina altered lamb metabolism and antioxidant status and reshaped the cecal microbial community, with microbial shifts associated with changes in serum indices.

Rhizosphere microorganisms are important components of grassland ecosystems, but the rhizosphere microbiome of the poisonous and medicinal plant Stellera chamaejasme L. remains poorly characterized. In this study, shotgun metagenomic sequencing was used to compare the taxonomic composition, community structure, differentially enriched taxa, and KEGG-based functional potential of rhizosphere microbial communities associated with S. chamaejasme from three typical steppe regions in Inner Mongolia. Acidobacteria, Proteobacteria, and Actinobacteria were the dominant phyla, while Sphingomonas, Bradyrhizobium, and Streptomyces were among the dominant genera. Genus-level profiles and ordination analysis showed region-associated community patterns, and rarefaction curves indicated that sequencing depth was sufficient to capture most detectable taxa. LEfSe analysis identified region-associated differentially enriched taxa, including Sphingomonas-, Bradyrhizobium/Nitrospira-, and Streptomyces/Solirubrobacter-associated taxa. KEGG annotation suggested broadly similar major functional categories across regions, with some differences in the relative abundance of metabolic pathways. These results provide baseline metagenomic information on S. chamaejasme rhizosphere communities. Because of the limited replication and lack of soil physicochemical measurements, ecological mechanisms should be tested in future studies.