Genotype-Dependent Sexual Dimorphism in Growth Performance, Feed Efficiency, and Survivability of Dual-Purpose and Layer Chickens Under Tropical Production Systems

Sexual dimorphism plays a pivotal role in shaping growth performance, feed efficiency, and survivability in poultry production systems, particularly under tropical conditions where environmental stressors may influence genotype expression. This study investigated sex-linked performance differences among three commercially relevant chicken strains—Noiler, Aco Black, and Isa Brown—during the first eight weeks of rearing under Nigerian tropical conditions. A total of 360 day-old chicks (60 males and 60 females per strain) were raised in a completely randomized design. Growth parameters including weekly body weight, body weight gain, feed intake, feed conversion ratio (FCR), and mortality were recorded and analyzed using analysis of variance. Significant strain and sex effects were observed across most performance indices. Noiler males exhibited the highest growth performance, achieving a final body weight of 1201.86 g, total weight gain of 1149.14 g, and the most efficient FCR (2.31). However, this rapid growth was accompanied by the highest mortality rate (50% in males), indicating compromised survivability. In contrast, Isa Brown birds recorded the lowest growth performance (female final weight: 682.60–697.20 g) but achieved the highest survival rate (up to 100%). Aco Black demonstrated intermediate growth (male final weight: 916.00 g) with high survivability (96–100%), reflecting balanced dual-purpose potential. The magnitude of sexual dimorphism varied among strains, with males consistently outperforming females in growth traits by week eight. Overall, the results highlight a trade-off between accelerated growth and survivability, underscoring the need for sex-specific and strain-oriented management strategies to optimize poultry productivity under tropical production systems