Manipulation of silage fermentation for ruminant health via probiotic lactic acid bacteria

Silage is a fundamental component of the diet in most ruminant production systems, valued for its ability to provide preserved year-round high-quality forage that supplies essential nutrients. Previous studies have predominantly focused on adding exogenous lactic acid bacteria (LAB) to promote the production of lactic acid and acetic acids, thereby achieving the dual goals of improved fermentation and nutrient preservation, along with reduced aerobic deterioration. This review highlights 2 primary strategies for using probiotic LAB to enhance animal health. First, the use of specific LAB strains to manipulate silage fermentation toward the production of silage with probiotic properties and second, the application of screened LAB to mitigate contaminants in silage. Inoculation of silage with specific probiotic strains shows preliminary promise in modulating the antioxidant status and immune functions of ruminants. Furthermore, novel LAB inoculants have been developed to address biosecurity risks, including mycotoxins, foodborne pathogens, pesticide residues, and antibiotic resistance genes, thereby limiting the transmission of these undesirable elements through the "feed-animal-food" chain. In summary, probiotic LAB-derived silage (probiotic or functional silage) holds theoretical potential for improving ruminant welfare and product quality. However, large-scale, long-term studies under practical farming conditions are imperative to fully validate these biological effects and their benefits to both livestock health and food safety.