A crossbreeding experiment was executed between local strain of Golden Montazah (GM) and foreign breed of White Leghorn (WL) at the Poultry Research Farm, Department of Animal Production, Faculty of Agriculture, Benha University, Egypt, during the period from March 2008 to October 2010. After producing F1 (GM × WL) cross, inter-se mating was practiced to produce F2 (GM × WL)2, F3 ((GM× WL)2)2 crossbreds. Data on 996 pullets fathered by 79 sires and mothered by 441 dams produced from five genetic groups (two purebreds and three crossbreds) were used. It was intended to: estimate non-genetic effects (e.g. genetic group and year or month-year) affecting egg production and egg quality traits, estimate genetic parameters (additive genetic variance, permanent environmental variance, heritability and correlations (genetic and environment) for these traits in purebred and crossbred chickens, estimate crossbreeding effects (direct additive effects, direct and maternal heterosis, and direct recombination), and to try producing a synthetic line of chickens under hot climate conditions in Egypt.
The studied egg production traits were: age (ASM) and body weight (BWSM) at sexual maturity, weight of the first egg (WFE), egg number (EN90D) and egg mass (EM90D) during the first 90-days, total egg number (EN120D) and total egg mass (EM120D) during the 120-days of laying, and rate of laying egg per day during 90 days (RL90D) and 120 days (RL120D). Partial recording traits such as period (days) in which first ten eggs were laid (PF10E), egg mass for first ten eggs (EMF10E), egg number (EN2D/W) and egg mass (EM2D/W) for two days per week, egg number (EN1W/M) and egg mass (EM1W/M) for one week per month, as well as pause periods during 90 days (PP90D) and 120 days (PP120D) were studied.
Numbers of 6103 eggs were collected from all genetic groups to study egg characteristics. The studied egg quality traits were: egg weight (EW), albumen weight (AW), yolk weight (YW), shell weight (SW), Haugh units (HU), egg shape index (ESI), albumen index (AI), yolk index (YI) and shell thickness (STH). Single - trait animal model analysis was used to analyze the data.
The results obtained can be summarized as follows:
First: Egg production traits:
1. Breed of WL had superiority (P |
