Table 2.

Factors influencing gut microbiota composition in animals.

Factor	Description	Impact
Host Ecology	Temperature, pH, Oxygen levels, Nutrient availability	Shapes microbial growth and survival
Host Genetics	Mucosal barrier function, Immune response	Influences susceptibility to specific microbes
Diet	Directly influences microbial survival and growth	Most significant environmental factor
Habitat	Local environment (soil, water, flora, fauna)	Provides source of colonizing microbes
Stress	Gut–brain axis activation, Stress hormone release	Alters gut permeability, immune response, and diversity
Husbandry Practices	Feeding regimens, Hygiene protocols, Disease management	Influences gut microbiota composition and overall gut health
Microbial Interactions	Competition, Cooperation, Cross-feeding	Shapes community structure and function
Disease	Pathogen invasion, Immune activation, Tissue damage	Disrupts microbial communities and impairs gut barrier function
Antibiotics	Medical treatment or environmental contamination	Dramatically alters gut microbiome
Environmental Toxins	Metabolism by gut microbes	May lead to dysbiosis and altered microbial transformation processes