Evaluation of genotype by environment interactions on growth and egg production traits of tropically adapted chicken breeds under smallholder production systems in two districts of Tigray Regional State, Ethiopia

Ethiopian local chickens are well adapted to diverse environments but have low production performance. To enhance egg and meat production and improve the lives of subsistence farmers, the African Chicken Genetic Gain (ACGG) project introduced tropically adapted exotic and locally improved breeds into the country. The project evaluated their meat and egg productivity under diverse environments and management systems. The study was conducted in Kelte-Awlaelo and Seharti-Samre districts of the Tigray region. Five breeds: improved Horro, Kuroiler, Koekoek, Sasso, and Sasso-Rhode Island Red (S-RIR) chickens were used. Two villages per district were purposively selected. From each Village, 40 households were selected, and each household received 25 chicks of a randomly selected breed. Data were analyzed using the General Linear Model (GLM) procedure in R software. Sasso chickens had higher ( P < 0.001) weight at 90, 120, and 150 days, while Kuroiler chickens were superior ( P < 0.001) at 180 days and had an average daily weight gain compared to the other breeds. The district significantly ( P < 0.05) affected the body weight only at certain ages. Koekoek and Horro were inferior ( P < 0.05) in body weight at all ages. Sasso and S-RIR chickens reared in Seharti-Samre district performed better ( P < 0.001) than those in Kelte-Awlaelo in most of the growth traits. Except for S-RIR, Horro chicken had higher ( P < 0.05) hen-day egg production up to 30 weeks than the rest of the breeds reared in Saharti-Samre. All chicken breeds had higher ( P < 0.01) HDEP% and HHEP% (except S-RIR) up to30 weeks in the Kelte-Awlaelo than Saharti-Samre. A significant difference was observed for genotype by environment interaction on growth and egg production traits, while the three-way interactions (breed x district x sex) were only significant for ADG. Overall, despite all the experimental chickens being dual-purpose types, Sasso and Kuroiler breeds performed well in meat production, while Koekoek and S-RIR outperformed in egg production.