ESTIMATION OF CROSSBREEDING EFFECTS FOR EGG PRODUCTION TRAITS IN A CROSSBREEDING EXPERIMENT INVOLVING TWO LOCAL STRAINS OF CHICKENS By

Abstract: A crossbreeding experiment was carried out between two Egyptian strains of chickens namely Mandarah (MN) and Matrouh (MA). Numbers of 668 pullets fathered by 71 sires and mothered by 462 dams produced from four genetic groups (the two purebred strains and their reciprocal crosses) were used. The studied traits of egg production were age at sexual maturity (ASM), body weight at sexual maturity (BWSM), weight of the first egg (WFE), egg number at first 90-days (EN90D), egg mass at first 90-days (EM90D), total egg number for 210-days (EN210D) and total egg mass for 210-days (EM210D). While the partial recording of egg production were period for first ten eggs (PF10E), egg mass for first ten eggs (EMF10E), egg number for one week per month (EN1W/M), egg mass for one week per month (EM1W/M), egg number for two days per week (EN2D/M) and egg mass for two days per week (EM2D/M). Multi-trait animal model and multiple-trait Gibbs Sampler were used to analyze the data of egg production traits. Results showed that MN strain was favored in all the studied traits compared to MA strain. The differences between the two strains were highly significant (P≤0.01) for all the traits, except ASM and PF10E. Estimates of direct additive effects were positive (negative for only ASM) and highly significant (P≤0.01) for all the studied traits (except ASM and PF10E). Most estimates of maternal breed effects were negative and ranged from low (0.24%) to moderate (-4.65%) in magnitude. Estimates of direct heterosis (