Phytase-lactobacillus co-fermentation of alfalfa silage: Enhancing mineral availability and beneficial metabolites.

Abstract

Alfalfa silage is an important feed resource, but its nutritional value is often limited by high buffering capacity and insufficient natural fermentative microorganisms. Given that 23 % of phosphorus in alfalfa exists as phytate phosphorus, which is wholly or partly bound to fiber, this study proposes a novel strategy combining lactic acid bacteria with phytase to improve silage quality. Results showed that inoculation with Lactiplantibacillus pentosus (L. pentosus) significantly reduced neutral detergent fiber (NDF) and acid detergent fiber (ADF) contents, lowered the pH, increased lactic acid production, and promoted the dominance of Lactiplantibacillus while decreasing the relative abundance of Kosakonia. L. pentosus could also promote the accumulation of beneficial metabolites such as amino acids, peptides, fatty acids and organic acids (e.g., glutamic acid, Val-Pro, linoleic acid, lactate). Meanwhile, phytase reduced NDF and ADF contents and modified the phosphorus fractions in alfalfa silage; however, its impact on microbial composition was limited. The combination of L. pentosus and phytase exerted combined effects by enhancing fermentation quality, increasing mineral solubility, and modulating amino acid, carbohydrate, and nucleotide metabolism, thereby significantly improving the nutritional value of alfalfa silage. In conclusion, targeted inoculation with L. pentosus effectively improves alfalfa silage quality, and its combination with phytase further enhances the nutritional value.

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