Estimation of Heterosis, Combining Ability and Reciprocal Effects for Production, Reproduction, Carcass Characteristics and Egg Quality Traits in Four Genetic Groups of Chicken from a Full Diallel Cross
No Thumbnail Available
Date
2026
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Addis Abeba University
Abstract
Crossbreeding is an effective strategy for improving productivity and adaptability of chickens under diverse production environments. This study evaluated heterotic effects (He ), general combining ability (GCA), specific combining ability (SCA), reciprocal effects (RE), and maternal effects (Me ) for production, reproduction, carcass characteristics, and egg quality traits in a 4×4 full diallel cross involving four chicken breeds: Improved Horro (H), Commercial Sasso (S), Potchefstroom Koekoek (K), and Dzwhite feathered (D). The experiment was conducted at the poultry research farm of Werer Agricultural Research Center (WARC), located in Amibara Woreda of the Afar Regional State, Ethiopia. A total of 960 purebred and F1 hybrid chickens representing sixteen genetic
groups were reared in a completely randomized design to evaluate growth performance, with body weight (BW) recorded from hatch to 14 weeks of age. At 24 weeks, 288 chickens (144 males and 144 females), comprising 18 birds per genotype (9 males and 9 females), were used for carcass component analysis. Fertility and hatchability traits were monitored throughout the incubation period. Egg production data were collected from 672 hens, with eggs recorded twice daily from the onset of lay until 40 weeks of age to determine egg production. Egg quality traits were evaluated using 480 eggs (30 eggs per genetic group)
randomly sampled at peak production (32 weeks of age). Heterosis estimates revealed that crosses between S males and K or D females (including reciprocals) exhibited the strongest positive He for BW throughout the growth period, whereas K×D crosses showed negative H , and H×K crosses displayed low and showed decreasing trend after WK 10. The GCA effects were highly significant (P < 0.0001), underscoring the importance of additive gene effects on BW, while SCA significantly influenced early-age BW (hatch, WK 2, 4, and 10), highlighting non-additive genetic contributions. The RE was significant only at hatch, WK 2, and WK 10, suggesting transient maternal or paternal influences. These findings suggest prioritizing parental GCA for consistent BW gains and developing broiler lines from S sires crossed with K or D dams and H sires with S dams. Carcass traits showed moderate to high heterosis in several crosses, particularly H×S, S×K, S×D, and H×K, with strongerresponses in males. The S breed exhibited the highest positive GCA for slaughter, dressed, and eviscerated weights, while H showed negative GCA effects. Favorable SCA estimates were observed mainly in H×S, S×K, and K×D, and significant reciprocal effects indicated important maternal influences. Reproductive traits showed generally positive heterosis, with H×K and H×S crosses exhibiting superior fertility and hatchability. Genotype K showed the highest positive GCA for fertility and hatchability traits, whereas H showed negative GCA effects. The H×K cross demonstrated the best SCA for reproductive performance, and significant reciprocal effects confirmed the importance of cross direction. For egg production traits, 800 chickens were evaluated over 40 WK, with significant genotypic variations (P < 0.0001) in age at first egg (AFE), body weight at sexual maturity (BWSM), egg weight at first egg (EWAFE), egg number (EN), hen-housed egg production (HHEP), hen-day egg production (HDEP), and egg mass (EM). Heterosis varied widely: BWSM and EM showed positive He in most crosses, while AFE consistently exhibited negative He . Notably, the K×H cross demonstrated the highest He for HHEP (26.85%), HDEP (29.44%), EM (40.88%), and EN (28.27%), while D×H and K×S crosses also displayed strong heterosis for key traits. Reciprocal crosses generally showed positive H e for all traits except AFE. Both GCA and SCA were highly significant (P < 0.0001), with
GCA/SCA ratios indicating non-additive dominance for AFE, additive influence for EWAFE, and balanced additive/non-additive effects for HHEP, HDEP, EM, and EN. RE and Me further modulated trait expression, supporting optimized crossbreeding strategies such as using K sires with H/S dams and D sires with H dams to enhance egg production. Egg quality traits were assessed using 480 eggs from purebreds and crossbreds, evaluating egg weight (EWT), egg length (EL), egg width (EW), shell weight (SWT), shell thickness (ST), shell ratio (SR), albumen height (AH), albumen width (AW), yolk height (YH), yolk width (YW), yolk weight (YWT), yolk ratio (YR), and Haugh unit (HU). Positive He was observed for most traits, with significant GCA effects (P < 0.001) for EWT, EL, EW, AW,
YW, YWT, and YR, while SCA influenced all traits (P < 0.001). The K×S cross showed positive RE for EWT and AW, whereas D×S had the highest RE for ST. Additive effects primarily governed EWT and YWT, while non-additive effects dominated EL, EW, ST, and YR. Maternal effects significantly varied across genotypes, emphasizing their role in egg quality. In conclusion, these findings underscore the importance of tailored breedingstrategies based on trait-specific genetic architectures. For growth, leveraging high-GCA parents is critical, while crossbreeding programs should prioritize synergistic heterotic combinations like S×K/D for broilers and K×H/S for layers. Egg quality improvement requires balancing additive and non-additive selection, supported by molecular tools for
precision. This integrated approach enhances genetic gains across production traits in poultry breeding.
Description
Keywords
Combining ability, Diallel cross, Heterosis, Maternal effect, Reciprocal effect