Two local breeds, namely Fayoumi (F) and Dandarawi (D) and two exotic ones named Rhode Island Red (R) and White Leghorn (L) were used in 4x4 diallel cross mating system. Thirty-two breeding pens were used. Two sires were mated to 16 dams in each breeding pen. Progeny of F1 of all breed groups (16 groups) were produced in two hatches within one year. Records of 587 hens were used to estimate general combining ability (GCA), heterosis, specific combining ability (SCA), maternal ability (MA) and reciprocal or sex-linked (SL) effects on productive traits [age at sexual maturity (ASM), body weight at sexual maturity (BWSM), egg production during the first 90-days (EP90D) and total egg production (TEP)]. A simple additive genetic model using crossbreeding program was used to determine the crossbreeding effects responsible for the differences among breeding groups.
Results showed that F hens had the earliest ASM (190.8 d) over all purebreds, followed by L (200.4 d). Purebred of R gave the highest BWSM, EP90D and TEP traits. Differences between means for productive traits of exotic and native breeds were significant (P<0.05). Average of crossbreds gave the earlier ASM than purebreds. Most of heterotic effects were highly significant (P<0.01) on ASM, BWSM traits, while it was significant (P<0.05) effect of D breed only on EP90D and non-significant for TEP. Crossbreds of LxF, FxL, DxR and LxR gave the highest heterosis for ASM, BWSM, EP90D and TEP, respectively. The percentages of heterotic effects came from these crosses were 6.1, 6.9, 18.4 and 20.1%, respectively. Significant (P<0.05 or 0.01) differences between purebreds for the effects of GCA, MA, SCA and SL were obtained on most the studied traits. The F breed gave the lowest (P<0.01) and negative effect of GCA on ASM, while D had superior MA for the same trait. The R had superior estimates (P<0.05 or 0.01) for GCA and MA in BWSM and TEP traits. Clearly, the RxF and LxD crosses gave the lowest (P<0.01) negative estimates of SCA for ASM trait compared to the other crossbreds. The RxD gave the highest (P<0.01) positive estimates of SCA for traits of BWSM and TEP. The RxF and RxD crosses had superior (P<0.05 or 0.01) SL effects for BWSM and EP90D traits, respectively.
From the previous results, it could be concluded that R sires (as an exotic breed) and F and/or D dams (as a native breed) would be selected to produce birds with earlier ASM and higher egg production in Egypt through crossbreeding programs. |
