Solid-state microbial fermentation (SSMF) has been established as an effective bioprocessing strategy to augment the nutritional value of plant-derived feed substrates while reducing anti-nutritional factors (ANFs). However, there have been limited studies on the effects of microbial solid-state fermentation on the nutritional value and potential functional components in cottonseed hulls. This study investigated the nutritional enhancement of cottonseed hulls through anaerobic solid-state fermentation mediated by Candida utilis CU-3, while exploring the functional potential of the fermented feed by analyzing fungal community dynamics and metabolite profiling. The laboratory-preserved free gossypol-degrading strain Candida utilis CU-3 was inoculated into unsterilized, crushed, and screened cottonseed hulls for solid-state fermentation at room temperature for 10 days. The results demonstrated that, compared to the control group, the experimental group achieved a 61.90% increase in free gossypol degradation rate, a 27.78% improvement in crude protein content, and a 5.07% reduction in crude fiber, while crude fat showed no significant difference. During the fermentation process, microbial diversity decreased, and Candida utilis CU-3 became the dominant species. Untargeted metabolomics data revealed that cottonseed hulls inoculated with Candida utilis CU-3 produced functional bioactive compounds during fermentation, including chrysin, myricetin (anti-inflammatory, antibacterial, and antioxidant activities), and ginsenoside Rh2 (anticancer, antibacterial, and neuroprotective properties). This study demonstrates that inoculating Candida utilis CU-3 into cottonseed hulls enhances their health-promoting potential through the biosynthesis of diverse functional metabolites, providing a theoretical foundation for improving the nutritional profile of cottonseed hull-fermented feed.

Due to its high content of lignocellulose, cotton stalk is difficult to degrade naturally and utilize effectively, so it is often regarded as waste. In this study, the effects of Pleurotus ostreatus XH005, Lactiplantibacillus plantarum LP-2, and cellulase enzyme on the cotton stalk substrate under aerobic solid-state fermentation (SSF) conditions were investigated, and the metabolites were analyzed to identify potential functional compounds in the cotton-stalk-fermented feed. Preliminary optimization results obtained through single-factor experiments were as follows: fermentation time 14 days, XH005 inoculum size 8.00% (v/m), material-to-water ratio 1:0.50 (v/m), LP-2 inoculum size 2.00% (v/m), and cellulase addition 0.60% (m/m). Based on these single-factor experimental results, XH005 inoculum size, LP-2 inoculum size, material-to-water ratio, and cellulase addition were selected as independent variables. Through response surface methodology (RSM) optimization experiments, 29 experimental groups were designed. Subsequently, based on Box–Behnken analysis of variance (ANOVA) of lignin and cellulose content, along with contour and response surface plots, the optimal aerobic solid-state fermentation parameters were determined as follows: fermentation time 14 days, XH005 inoculum: 7.00% (v/m), material-to-water ratio: 1:0.55 (v/m), LP-2 inoculum: 2.00% (v/m), and cellulase enzyme addition: 0.65% (m/m). Results showed that compared with the control group (CK), the optimized group exhibited a 27.65% increase in lignin degradation rate and a 47.14% increase in cellulose degradation rate. Crude protein (CP) content increased significantly, while crude fiber (CF), detergent fiber and mycotoxin contents decreased significantly. Non-targeted metabolic analysis indicated that adding cellulase and inoculating Pleurotus ostreatus XH005 and Lactiplantibacillus plantarum LP-2 in aerobic SSF of cotton straw feed produced functionally active substances such as kaempferol (C343), carvone (C709) and trilobatin (C604). Therefore, this study demonstrates that microbial-enzyme co-action SSF significantly enhances the nutritional composition of cotton stalk hydrolysate. Furthermore, this hydrolysate is suitable for the production of functional compounds, endowing the fermented feed with health-promoting properties and enhancing the utilization of cotton processing byproducts in the feed industry.

The purpose of this study is to investigate the effects of silage inoculants (FJ) and natural fermentation (CK) on the quality and microbial community of whole-plant corn silage under different fertilization treatments, including conventional fertilization (CK), liquid microbial inoculant and conventional fertilization (JJ), and microbial organic fertilizer and conventional fertilization (YJ). After 30 days of room-temperature fermentation, parameters including pH, LA, CP, starch, ADF, NDF, and the microbial community were determined. The results showed that after 30 days of ensiling, silage inoculants significantly affected the nutritional components and fermentation parameters of whole-plant corn silage under different fertilization treatments. Furthermore, the two factors (silage inoculants and different fertilization treatments) exhibited a significant interaction effect. Simple effects analysis revealed that the significant interaction was mainly driven by a more pronounced differential effect of fertilization treatments on the nutritional indicators (starch, CP, ADF, and NDF) under silage inoculant (FJ) addition than under natural fermentation (CK) (p < 0.05). Among all silage treatments, the silage inoculants + microbial solution drip irrigation and conventional fertilization (FJJJ) group exhibited relatively superior silage quality. Specifically, the FJJJ group had the lowest contents of pH, ADF, and NDF, along with the highest contents of lactic acid (LA) and ether extract (EE). The addition of silage inoculants under different fertilization treatments consistently increased the abundance and reinforced the dominance of Lactobacillus in the microbial community. This effect was most pronounced in the FJJJ group, which showed the highest relative abundance. In contrast, the relative abundance of genera such as Pantoea, Acinetobacter, Klebsiella, and Pseudomonas decreased significantly. In summary, appropriate fertilization treatments combined with the addition of silage inoculants contribute to enhancing the quality of whole-plant corn silage and improve the fermentation microbial community of the silage. These findings provide a theoretical basis for producing high-quality corn silage.

Probiotics improve the quality of silage during the planting and fermentation processes. This study was designed to investigate the accumulation of nutritional components in the fresh corn variety Jingkenuo 2000 waxy maize under different fertilization conditions and its effectiveness as silage feed. The nutrient accumulation trends of dry matter (DM), starch, neutral detergent fiber (NDF), acid detergent fiber (ADF), crude protein (CP), and ether extract (EE) in the stems, leaves, grains, and whole plant of Jingkenuo 2000 waxy maize were evaluated during different growth cycles. The relative feed value (RFV) was also assessed, with the results showing that the whole plant of Jingkenuo 2000 waxy maize at the wax stage was most suitable for use as silage. The experiment conducted in the present study was carried out in a completely random block design with two additives and three fertilizer application conditions: no-additive + conventional fertilization treatment (CKCK); no-additive + conventional fertilization + drip irrigation of bacterial solution treatment (CKJJ); no-additive + conventional fertilization + microbial organic fertilizer treatment (CKYJ); additive + conventional fertilization treatment (FJCK); additive + conventional fertilization + drip irrigation of bacterial solution treatment (FJJJ); and additive + conventional fertilization + microbial organic fertilizer treatment (YJFJ). Additionally, the nutrient composition, fermentation quality, and bacterial community structure of the silage fermentation treatments were analyzed. The results indicate that there was significant interaction between the additive and fertilization treatments, with them significantly influencing the parameters CP, EE, NDF, ADF, and RFV (p < 0.01). In particular, the treatment combining additives, conventional fertilization, and drip irrigation of bacterial solution exhibited the highest CP, EE, and starch (p < 0.01) among all the tested treatments, while also displaying the lowest NDF and ADF contents (p < 0.01). Furthermore, this treatment reduced the pH value (p < 0.01), decreased bacterial diversity, and fostered the growth of Lactobacillus. Overall, the findings presented herein demonstrate that, through precise nutritional accumulation monitoring and scientific biological pretreatment methods, Jingkenuo 2000 waxy maize has the potential to become a high-quality silage feed.