理学最新文献

Background: The gayal (Bos frontalis), a semi-domesticated bovine species, demonstrates exceptional adaptability to lignocellulose-rich diets dominated by bamboo, suggesting the presence of a specialized gastrointestinal microbiome. However, the functional mechanisms underlying this host-microbiome interaction remain poorly understood. Here, we conducted integrated metagenomic and metatranscriptomic analyses of rumen, cecum, and colon digesta from yellow cattle and gayal raised on the same bamboo-based high-fiber diet.

Results: The results showed that gayal exhibited superior fiber-degrading capacity relative to yellow cattle, evidenced by significantly higher (P < 0.05) fiber digestibility, cellulase and xylanase activities, and increased volatile fatty acids production despite identical feed intake. Microbial community analysis revealed distinct composition in both the rumen and hindgut of gayal compared to yellow cattle, with notable enrichment of taxa specialized in lignocellulose degradation. Metatranscriptomic profiling further identified upregulation of key lignin-modification enzymes, particularly AA6, AA2, and AA3, primarily encoded by Prevotella, Cryptobacteroides, Limimorpha, and Ventricola. These enzymes are known to modify lignin structure to increase polysaccharide accessibility. These results demonstrate that gayal hosts a unique and metabolically active gastrointestinal microbiome capable of efficient lignocellulose deconstruction through a coordinated enzymatic cascade, especially effective in dismantling lignin barriers.

Conclusions: This study provides novel insights into host-microbiome co-adaptation to fibrous feeds and highlights the potential of gayal-derived microbial consortia and enzymes for improving roughage utilization in ruminant agriculture.

Background: Piglets are highly susceptible to oxidative stress, which can reduce growth performance and cause intestinal damage. Piceatannol (PIC), a natural bioactive substance enriched in Chinese rhubarb (Rheum officinale) and certain dark purple fruits, shows excellent antioxidant properties in our previous cell-based high-throughput screening. However, its effect on piglet growth performance and antioxidant capacity as well as underling mechanism has not been thoroughly investigated.

Methods: One hundred weaned pigs (28 days of age, 8.71 ± 0.20 kg) were randomly assigned to 4 treatments with 5 replicates of 5 pigs per replicate. The experimental diets consisted of: 1) basal diet, 2) basal diet + 100 mg/kg PIC, 3) basal diet + 200 mg/kg PIC, and 4) basal diet + 300 mg/kg PIC. On d 15 and 35, one pig from each replicate was selected for sampling. The growth performance was monitored during a 35-day trial. In addition, H₂O₂-challenged IPEC-J2 cells served as an in vitro model to investigate the antioxidant mechanisms of PIC. IPEC-J2 cells were treated with 1,000 μmol/L H₂O₂ in the presence or absence of 10 μmol/L PIC.

Results: Dietary PIC at 200 mg/kg significantly enhanced growth performance, as evidenced by increased average daily gain and feed conversion rate (P < 0.05). PIC supplementation markedly improved systemic antioxidant capacity, with elevated serum total antioxidant capacity, catalase activity, and glutathione levels, along with reduced malondialdehyde content (P < 0.05). Notably, PIC modulated the gut microbiota composition, increasing the amounts of beneficial genera (e.g., Blautia and Faecalibacterium), and these microbial shifts significantly correlated with improved antioxidant indices. In vitro, PIC pretreatment effectively protected IPEC-J2 cells against H₂O₂-induced oxidative damage by reducing reactive oxygen species generation and lipid peroxidation (P < 0.01). Mechanistically, PIC exerts its antioxidant effects through Nrf2 pathway activation, upregulating endogenous antioxidant enzymes (P < 0.05) while simultaneously inhibiting apoptosis via the regulation of the Bcl-2/Bax ratio and caspase-3 cleavage (P < 0.01).

Conclusions: PIC improved the growth performance and health status of weaned piglets through the regulation of Nrf2-mediated redox homeostasis and modulation of the related gut microbiota, offering a potential new natural antioxidants for mitigating weaning stress in piglets.