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

Abstract

The aim of the study was to evaluate genotype by environment interactions (GEI) on growth and egg production traits of tropically adapted chicken breeds under smallholder production systems. The study was conducted in Kelte-Awlaelo and Seharti-Samre districts of eastern and south eastern zones of Tigray region, Ethiopia. Improved Horro, Kuroiler, Koekoek, Sasso and S-RIR chickens were used as experimental animals. Two Villages per district were purposively selected. From each Village, 40 households (HHs) were involved in the experiment and each HHs received 25 birds of a randomly selected breeds. The data were analyzed using the GLM procedure of R v.3.6.1 running on RStudio version 1.2.5001. Sasso chickens had higher (P <0.001) weight at 90, 120 and 150 days while, Kuroiler were superior (P <0.001) at 180 days and ADG than the other breeds. District significantly (P <0.05) affected the body weight of chickens only at certain ages. Male chickens performed better (P <0.05) than females across all ages. Among the male chickens, Kokekoek 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 Kelte-Awlaelo in most of the body weight measurements. Koekoek chicken had higher (P <0.001) HDEP% to 30 weeks as compared to Horro and Sasso chickens reared in Kelte-Awlaelo district. Except for S-RIR, Horro chicken had higher (P <0.05) HHEP% to 30 weeks than the rest breeds reared in Saharti-Samre district. Sasso chickens had lower (P <0.05) mean AFE as compared with the other breeds reared in Kelte-Awlaelo district. Chickens reared in Kelte-Awlaelo district were superior (P <0.001) than those in Seharti-Samre on egg production traits. Except for Sasso and Horro all chicken breeds attained earlier maturity in Seharti-Samre district than in Kelte-Awlaelo. All chicken breeds had higher (P <0.01) HDEP% and HHEP% (except S-RIR) to 30 weeks in Kelte-Awlaelo district than Saharti-Samre. Significant difference was observed for breed by environment/district interaction on the studied growth and egg production traits. The three way interactions between breed, district and sex factors were found to be significant only for the growth trait of ADG. Sasso followed by Kuroiler breeds are the best options to improve meat productivity of both districts, while Koekoek and S-RIR are preferable breeds to enhance egg productivity in Kelte-Awlaelo and Seharti-Samre districts, respectively.