Identification, quantification and bio-degradation of anti-nutritional factors with composite bacteria-enzyme inoculation in ramie (Boehmeria nivea. L) and its plant silage

Anti-nutritional factors (ANFs) are widely present in most plant-based feeds. However, their presence in ramie forage is poorly understood, and the lack of targeted degradation technologies severely hinders its efficient utilisation. To comprehensively identify the anti-nutritional components in ramie forage and explore their degradation techniques, comparative metabolomics and physicochemical analysis were employed to qualitatively and quantitatively characterize the ANFs present in ramie harvested at different growth stages. An orthogonal design was adopted to investigate the biodegradation of ramie ANFs via silage fermentation supplemented with a composite bacteria-enzyme inoculant. Five key ANFs were identified and quantified in ramie, including non-starch polysaccharides (NSPs), saponins, biogenic amines, alkaloids and coumarins. Among these, pectin and cellulose within NSPs, as well as coumarins, are likely to exert the most significant adverse effects. Delayed harvesting not only improved yield but also significantly elevated cellulose and hemicellulose contents ( p < 0.05), while concurrently reducing the content of pectin and total coumarins to a marked extent ( p < 0.05). Silage fermentation with composite bacteria-enzyme inoculant resulted in reductions of 41.05%, 44.51% and 34.71% in the content of total coumarins, pectin and cellulose respectively, indicating its considerable potential for degrading ANFs in ramie. A comprehensive evaluation based on multi-indicator determined the optimal harvesting height for forage ramie to be 78.41 ± 5.90 cm, the most effective silage fermentation system comprised 250 mg kg −1 of experimental composite bacteria and 100 mg kg −1 of composite enzymes over a 15-day ensiling period. Coumarins, pectin and cellulose were identified as the dominant ANFs in forage ramie. Silage fermentation with composite bacteria-enzyme inoculant was found to be an effective way of degrading them. These findings provide a scientific basis for improving and processing ramie forage varieties and utilising ramie feed products.