Egg Production Evaluation for Kurdish Local Chicken in Two Different Environments and Estimates of Their Genetic Parameters
The current experiment was conducted in both of animal production fields in the directorate of Agricultural research in Erbil and Sulaimani provinces. Eggs included in this study collected when the production percentage of the flock was 5% and continued for 16 weeks starting at April 2016.Three families of each of two lines include local black, and black with brown neck were bred in both areas. Water was available ad libitum and the details of management, feeding, and health program were the same and described earlier. Weight and number of eggs produced were recorded daily.General Linear Model used to analyze the studied traits. The model includes the genetic groups,environment and the interaction as effects of the traits. Scheffe's test was conducted to distinguish the significant differences between the least square means of the levels of each factor. Variance component of random effects were estimated according to Restricted Maximum Likelihood-REML method. Mixed model includes the effect of sire in addition to the above main effects. VCV matrices were tested for positive definiteness; in order to develop reliable estimates of genetic parameters. Averages of egg weight, daily egg production and daily egg mass were 58.95 g, 50.30 % and 29.65g, respectively.The present study showeda highly significant effect (p<0.01) of genetic groupon all studied traits, where Black with brown neck excelled the black in their egg weights, daily egg production and daily egg mass by 1.27 g, 15.94 % and 10.03 g respectively. The effect of environment was significant (p<0.01) only on egg weight, where the highest (60.01 g) and lowest (57.88 g) egg weight noticed in Sulaimani and Erbil respectively.Furthermore, the interaction affect the three studied traits significantly (P<0.01), wherethe black with brown neck bred in Sulaimani produced significantly higher egg weight. Highest (P<0.01) daily egg production was recorded for black brown neck bred in both areas. Accordingly, the significant and higher daily egg mass was calculated for black brown neck bred in both areas. Heritability estimates for egg weight, daily egg production and daily egg mass were 0.32, 0.18 and 0.13 respectively. Highest genetic (0.43) and phenotypic (0.53) correlations were found between daily egg production and daily egg mass, while the corresponding estimates between egg weight and daily egg production were negative and being -0.61 and -0.11 respectively, estimates between egg weight and daily egg mass were 0.31 and 0.10 on the same order. It could be concluded that black brown neck chicks surpassed the local black in all egg production traits. In the same genetic line, effect of the environment was clear as the weight of the egg was affected by the surrounding environment and was superior in the Sulaimani governorate. Estimates of genetic and phenotypic correlations between studied traits could be considered as useful for improve egg production. Keywords - Local Chicken, Egg Production, Genetic Parameters.