Soil-plant-animal properties and microbial reassembly distinguish cattle oral disease prevalence across converted Amazon pasture systems

Forest-to-pasture conversion can alter soil properties, forage composition, and microbial communities, but whether these changes are associated with bovine periodontitis remains unclear. We compared eight pasture systems in the Western Brazilian Amazon classified by high or low herd-level prevalence of periodontal lesions. Soil physicochemical properties, forage composition, microbial communities in soil, forage, and bovine subgingival biofilms, and the relative abundance of the streptomycin biosynthesis gene strB1 were evaluated. Although the systems had similar deforestation histories, low-prevalence pastures had finer-textured soils, greater soil Cu and forage Zn, and greater representation of Bacilli and Gammaproteobacteria. High-prevalence pastures had sandier soils, greater soil C:N ratios, lower micronutrient availability, and greater representation of Actinobacteria and Bacteroidetes. Microbial communities differed between prevalence classes in all three compartments, with higher alpha and gamma diversity and more compartmentalized co-occurrence networks in high-prevalence systems. Tax4Fun predicted greater representation of pathways related to carbohydrate metabolism and glycan biosynthesis in these systems, while qPCR showed higher strB1 abundance normalized to bacterial 16S rRNA gene abundance in soil and forage. These concurrent differences in soil properties, forage composition, and microbial communities were associated with bovine periodontitis prevalence. They do not demonstrate microbial transfer or causality but support the hypothesis that soil and forage conditions may influence environmental exposures related to oral microbiome dysbiosis.