Abstract
objectives: This study was conducted at Agricultural Research Center / Scientific Research Commission, from May 1 to September 20, 2025 to evaluate the productive performance of four chicken strains under heat stress conditions The findings highlight the limited attention given to local chicken breeds in Iraq despite their potential importance. Materials and Methods: The experiment included two commercial egg laying strains (ISA Brown and White Leghorn) and two local strains (Naked Neck and fully feathered local chickens). Birds were allocated into four treatments according to strain, with three replicates per treatment, and reared in floor pens. All birds were fed a standard layer diet and subjected to a 16-hour daily lighting program. Heat stress was imposed for 10 hours daily at 37°C.The evaluated traits included daily feed intake, egg production percentage, cumulative egg number, egg weight, egg mass, and feed conversion ratio (FCR). The results revealed significant differences among treatments. The Naked Neck chickens (T1) exhibited superior performance compared with the other treatments. This strain recorded the highest daily feed intake, egg production percentage, cumulative egg number, egg weight, egg mass, and the best feed conversion efficiency. In contrast, reductions in feed intake observed in the other treatments, particularly the fully feathered local strain (T4), were associated with poorer productive performance. The fully feathered local chickens recorded the lowest values for egg production, egg weight, egg mass, and feed conversion efficiency. The Naked Neck chicken, demonstrated a remarkable capacity to tolerate high ambient temperatures and maintain satisfactory productive performance under heat stress conditions. Conclusion: These results indicate that this local strain represents a valuable genetic resource that could contribute to improving poultry production under hot climate conditions.