General and Specific Combining Abilities for Egg Production Traits in a Two-Way Cross Between South African Local and Commercial Chicken Breeds.

This study aimed to determine the general combining ability (GCA) and specific combining ability (SCA) for egg production in a two-way cross between Potchefstroom Koekoek (PK) and Lohmann Brown (LB) chicken breeds. The study used 352 chickens in a completely randomized design. A total of 524 eggs were collected from the pure and crossbred chickens. R (Version 4.4.2) was used for data analysis. The results showed that the GCA effects were highly significant (p < 0.01) for age at first egg (0.50) and hen housed production (5.35), and SCA was highly significant (p < 0.01) for age at first egg (16.00) and hen housed production (36.49). GCA and SCA had no significant (p > 0.05) effect on external and internal egg quality traits. The GCA/SCA ratio results indicated that nonadditive influences (p < 0.05) body weight (-0.45) and egg weight (-0.92), while additive influences (p < 0.05) albumen ratio (5.89). The study concluded that selection for breeding, prioritizing parents with superior GCA, ensures predictable body weight. The results of the GCA/SCA ratio highlight selection and crossbreeding as ideal for improving body weight and egg weight. Furthermore, the use of a LB sire and PK dam is considered for developing a new strain.