Carcass Characteristicsand Adaptive Traits of F₁ Backcross Progenies Derived from Normal-Feathered, Naked-Neck, and Frizzle Crossbred Chickens under Humid Tropical Conditions
The productivity of poultry under humid tropical conditions is frequently constrained by high ambient temperature and relative humidity, which impair growth performance and carcass yield. Genetic strategies that enhance thermotolerance while maintaining desirable meat characteristics are therefore essential for sustainable poultry production in tropical environments. This study evaluated the carcass characteristics and Adaptive Traitsof F₁ backcross progenies derived from normal-feathered (NF), naked-neck (Na), and frizzle (F) indigenous chickens crossed with exotic broiler breeders (Anak strain) under humid tropical conditions. The experiment was conducted at the Teaching and Research Farm of Michael Okpara University of Agriculture, Umudike, Nigeria (05°29′N, 07°33′E), located within the humid rainforest agro-ecological zone. The prevailing climatic conditions (maximum temperature of 27–36 °C; relative humidity of 57–91%; annual rainfall of 2,177 mm) provided a natural thermal-stress environment suitable for evaluating thermotolerant genotypes. A total of 90 parent birds (45 indigenous and 45 exotic) were used to generate six genetic groups through main and reciprocal crossing involving exotic (E), NF, Na, and F genotypes. Artificial insemination was employed to ensure controlled mating. F₁ progenies were brooded and managed under standard husbandry practices. At six weeks of age, carcass evaluation was conducted on randomly selected birds following a 10-hour feed withdrawal. Parameters measured included live weight, dressed weight, dressing percentage, primal carcass cuts (breast, back, thigh, drumstick, wing), and internal organ proportions. Data were analysed using a Randomized Complete Block Design with hatch as a blocking factor. Analysis of variance was performed using SAS (Version 9.4), and means were separated using Duncan’s Multiple Range Test at P < 0.05. Significant (P < 0.05) differences were observed among genetic groups for live weight, dressed weight, dressing percentage, and most carcass components. Reciprocal crosses consistently outperformed main crosses. The highest live weight was recorded in F × E (2200.81 g), followed by Na × E (2137.33 g), while the lowest was observed in E × F (1550.69 g). Similarly, Na × E exhibited the highest dressed weight (1450.02 g) and dressing percentage (63.14%), significantly surpassing other groups. Breast yield, the most economically valuable cut, was highest in Na × E (30.60% of dressed weight), indicating superior muscle accretion. Back and thigh percentages were also significantly higher in Na × E, whereas F × E demonstrated relatively enhanced shank development. Neck and head proportions showed minimal variation among genotypes. The superior carcass performance of reciprocal crosses, particularly Na × E and F × E, suggests the influence of heterosis, maternal genetic effects, and improved adaptability of indigenous hens under humid tropical conditions. The naked-neck gene, characterised by reduced feather coverage, likely enhances heat dissipation, reduces metabolic heat load, and improves nutrient partitioning toward muscle development. Similarly, the frizzle gene may have contributed to improved thermoregulation and structural growth. These genetic advantages appear to mitigate the adverse effects of heat stress, thereby enhancing carcass yield. The findings demonstrate that the incorporation of naked-neck and frizzle genes into crossbreeding programmes significantly improves carcass performance under humid tropical environments. Among all genotypes evaluated, Na × E emerged as the most promising combination for meat production, combining high live weight, superior dressing percentage, and enhanced breast and thigh yields. The study underscores the importance of genotype selection and crossbreeding strategies in developing climate-resilient poultry suited to hot-humid production systems. These results provide valuable insights for breeding programmes aimed at improving meat yield and production efficiency in tropical regions.
