The current study aimed to investigate the solid-state fermentation process of Quercus liaotungensis (QL) by Bacillus subtilis (BS). The parameters included the inoculation amount, the soybean meal addition amount, the fermentation temperature and the ratio of material to water. The optimal process was determined based on the nutritional value, tannin content and DPPH clearance of QL after fermentation. The results showed that: (1) The parameters of the optimal process included inoculating 10⁶ BS per gram of QL, then adding 10% soybean meal, the ratio of material to the water of 100:80, and temperature at 33 °C for 72 h. (2) In the optimum fermentation conditions, the crude fiber content, and the ether extract content of QL decreased by 66.94% and 66.96%, respectively (p < 0.05). Moreover, the crude protein content and the ash content increased by 65.81% and 4.63%, respectively, after fermentation (p < 0.05). Additionally, the tannin content decreased by 62.77% (p < 0.05), and the DPPH scavenging rate decreased by 45.45% (p < 0.05) after fermentation, respectively. In summary, the QL significantly improved the nutritional value after the solid-state fermentation with BS.

This study investigated the effects of dietary guanidinoacetic acid (GAA) supplementation on growth performance, carcass traits, meat quality, intestinal morphology, and cecal microbiota composition in yellow-feathered broilers. A total of 360 one-day-old chicks were randomly assigned to five groups with diets containing 0 (control), 300 mg/kg, 600 mg/kg, 900 mg/kg, and 1200 mg/kg GAA. In the initial growth phase, GAA supplementation increased average daily gain (ADG) by 13.01%, 8.97%, and 12.95% for the 300, 600, and 900 mg/kg groups, respectively, and reduced the feed conversion ratio (FCR), though these changes were not statistically significant (p > 0.05). Higher GAA dosages (900 and 1200 mg/kg) improved post-slaughter pH levels in breast muscle, indicating better meat quality, and significantly enhanced intestinal barrier function by increasing villus height and the villus-to-crypt ratio. However, 1200 mg/kg GAA led to a significant increase in serum ALT levels, raising concerns about potential liver stress. Overall, 900 mg/kg GAA supplementation demonstrated the most beneficial effects across various parameters, suggesting it as an optimal dosage to enhance production performance and meat quality in yellow-feathered broilers. Future studies are encouraged to investigate its long-term safety and underlying mechanisms.