A simple crossbreeding experiment between Fayoumi (F) and Rhode Island Red (R) and their F1 of ½R½F and ½F½R crosses was conducted. A total number of 480 chicks produced from four genetic groups was used to estimate direct additive genetic effects (GI ), maternal effects (GM) and direct heterosis (HI ) for growth traits by using generalized least squares procedure. The studied traits were body weights at hatch, 2, 4, 6, 8 and 10 weeks of age and daily gains during the intervals of 0-2, 2-4, 4-6, 6-8 and 8-10 weeks of age. Candidate gallinacin genes of GAL 2, GAL 3, GAL 4 and GAL 5 were genotyped using PCR-RFLP, associating the SNP with body weights and gains. Direct additive effects were mostly significantly (P≤0.01) in favour of R breed by 7.4 to 57.9 g for body weights and by 0.8 to 1.8 g for daily gains. The estimates of maternal effect were mostly significantly (P˂0.01) in favour of R breed and ranging from 0.8 to 25.1 g for body weights and 0.5 to 2.3 g for daily gains. All the estimates for direct heterosis were positive and significant (P˂0.01) and ranged from 0.15 to 35.2 g for body weights and 0.3 to 1.5 g for daily gains. The GAL 2 gene was one homozygous genotype in the four genetic groups, while in GAL 3, GAL 4 and GAL 5 genes only one homozygous genotype in Fayoumi breed was observed. The genotypes of Gal 3 gene had significant associations with most body weights and gains (p