Copyright © 2018 IJRAS, All right reserved 291 International Journal of Research in Agricultural Sciences Volume 5, Issue 6, ISSN (Online): 2348 – 3997 Estimation of Heterosis, Combining Ability and Reciprocal Effects for Growth Traits in Chickens from a Full Diallel Cross Mohamed H. Khalil 1 , Ahmed A. Debes 2 and Mostafa K. Shebl 1* 1 Department of Poultry Production, Faculty of Agriculture, Alexandria University, Egypt. 2 Animal Production Research Institute, Agriculture Research Center, Ministry of Agriculture, Egypt. Date of publication (dd/mm/yyyy): 25/11/2018 Abstract – A 4x4 complete diallel cross was carried out involving four Egyptian local breeds of chickens: Alexandria (AA), Fayoumi (FF), Matrouh (MM) and Golden Montazah (GG). Data on body weight (BW) and body weight gain (BWG) at 4, 8, and 12 weeks of age were analyzed using complete diallel analysis. Heterosis estimates indicated that crossing between Fayoumi males and Matrouh females at earlier ages as well as between Matrouh males and Golden Montazah females at later age gave the highest heterotic effects for BW and BWG. General combining ability effects showed that additive genetic variance was important in determining BW and BWG and indicated superiority of AA breed in these traits. This breed therefore may be used as one of the parents if its improvement is sought through crossbreeding. The contribu- -tion from specific combining ability was significant for BW and BWG during all ages. Reciprocal recurrent selection would be advantageous to exploit non-additive gene effects to produce commercial broilers (FM and MG). Reciprocal effects were significant for BW. This cleared that sex-linked effects were important for the genetic improvement of BW. This study suggested that use of crossbreeding tool to develop new synthetic breeds suitable to Egyptian conditions with acceptance performance. Keywords – Diallel Cross, Heterosis, Combining Ability, Sex- Linked, Crossbred Chickens. I. INTRODUCTION The rapid growth of the human population in Egypt has led to the relatively high demand for protein sources. Poultry meat is the cheapest source of protein compared to animal protein forms and probably the most consumed. The relevance of poultry meat for humans also has been recognized by the UN Food and Agricultural Organization (FAO), who considers this widely available, relatively inexpensive food to be particularly useful in developing countries, where it can help to meet shortfalls in essential nutrients. Moreover, poultry meat consumption also contributes to the overall quality of the diet in specific ages and conditions (Franca Marangoni et al., 2015). The local gene pool (native and indigenous chickens) in Egypt still provides the basis for the poultry sector. The genetic resource base of the indigenous chickens could form the basis for genetic improvement and diversification to produce breeds adapted to local conditions. Crossbreeding is one of the tools for exploiting genetic variation and is a better option than selection to obtain birds with a faster growth rate that is adapted to native environmental condition (Segura- Correa et al., 2004). The performance of a breed or strain or line in cross combination can be evaluated in terms of general and specific combining abilities. Data for growth traits (body weight and body weight gain) on four local Egyptian breeds of chickens were used. These breeds were one native (Fayoumi), and three indigenous (Alexandria, Matrouh and Golden Montazah). This study was undertaken to evaluate the percent heterosis, general and specific combining ability, and reciprocal effects in a full diallel cross involving the above four breeds. II. MATERIALS AND METHODS This study was conducted at the Poultry Research Center, Poultry Department, Faculty of Agriculture, Alexandria University, Egypt during 2014/2015. The experimental pedigreed chickens (1776) were obtained by mating four local breeds of chickens in a full 4*4 diallel cross, which resulted in four pure-bred, six cross-bred and six reciprocal cross-bred progenies. These breeds were (Alexandria, Fayoumi, Matrouh and Golden Montazah). Sixteen pens representing 4 single sires of each breed were set up and each sire was concurrently mated to three females of its own breed and three females each of the other three breeds. Five hatches were used. Management conditions were similar throughout the experiment. The traits measured were individual body weights (BW) and body weight gain (BWG) in grams every 4 weeks from 4 to 12 weeks of age. Statistical Analysis: Data were analyzed for variation between the genotypes using the general linear model of SPSS software (IBM, SPSS, 2016). Differences were tested for significance using Duncan test (Duncan, 1955). Following linear model was tested to analyze the data: Yijkl = U + Gi + Hj + Sk + GHij + GSik + HSjk + GHSijk + eigkl Where: Yijkl = the observation on the genotype, U = the overall mean, Gi = the fixed effect of i th genotype, Hj = the fixed effect of j th hatch, Sk = the fixed effect of k th sex, GHij, GSik, HSjk, GHSijk = the interaction between the fixed effects, and eigkl = random error For the combining ability analysis and estimation of various gene effects, i.e., general combining ability (GCA), specific combining ability (SCA), and reciprocal effects (RE), the following fixed model of Griffing (1956) was used: Yij = U + gi + gj + sij + rij + 1/c ∑k eijk i, j = 1 to 4 k = 1 to nij