HETEROSIS FROM CROSSING SOME LOCAL STRAINS WITH TWO COMMERCIAL LINES OF LAYING HENS By

To determine the superior parents and hybrid combinations for developing a new hybrid with high genetic potential of egg production yield. Thus, heterotic analysis was used widely to compare different genetic groups derived from crossing four local strains of chickens (Baheij, Matrouh, Silver Montazah and Golden Montazah) with two commercial egg type chickens (Lohman Brown and Lohman Selected Leghorn). The current results showed superiority of Silver Montazah local strain in egg number at 90 d., of laying (EN1), egg number till 180 d., of laying (EN2), egg number till 240 d., of laying (EN3), egg number till 52 wks., of laying (EN4), egg weight at 52 wks., of laying (EW4) and annual egg mass (EM), with 48 eggs, 80 eggs, 128 eggs, 155 eggs, 53.5 g., and 8 kg., respectively. While, Golden Montazah local strain was the earliest local strains in reaching sexual maturity (ASM) 184 d., and it was superior in egg weights at 90 and 180 d., of laying (EW1 and EW2) with 51.9 and 52.4 g., respectively. The commercial lines Lohman Brown and Lohman Selected Leghorn gained either high (12 Kg.) or low (11 Kg.) annual egg mass (EM), respectively. Whereas, among the hybrid combinations, the LSL crosses were found to exhibit an outstanding higher estimates of egg production traits i.e. 186 d. (A.S.M), 39 eggs (EN1), 114 eggs (EN2), 148 eggs (EN3), 201 eggs (EN4) and 11 Kg. (EM) than LB crosses, which were associated with the heaviest egg weight at different laying periods studied i.e. 52.7, 53.0, 53.4 and 53.7 g., for EW1, EW2, EW3 and EW4, respectively. Also, all interaction effects were significant (P<0.01) indicating the presence of heterosis for all of the studied traits. Estimates of genetic variance components indicated that the nature of gene effects was additive for most of egg production traits, but age at sexual maturity was affected largely by dominance gene action. Generally, results of annual egg production, suggest that crossing the local strains with the two commercial lines were associated with an increase in egg production along with a reduction in age at first egg.