NOS2 and Salmonella Infections: Our results indicate that co-housing AA chickens with Tibetan chickens reduces the expression levels of pro-inflammatory cytokines (NOS2, TNF-α, IL-8, IL-1β, and IFN-γ) in the cecal tonsils of AA chickens, which suggests that co-housing with Tibetan chickens reduced the inflammatory response in AA chickens, thereby enhancing their resistance to Salmonella infection.