Comparative Evaluation of Growth, Laying Performance, and Egg Quality in Six Korean Native Chicken Crossbred Strains

Native poultry breeds are valuable genetic resources with considerable diversity, adaptability, and variation in productive traits. Despite their significance, many native strains have been underutilized in commercial breeding programs, highlighting the need for targeted characterization to support conservation and future genetic improvement. This study evaluated the growth performance, laying productivity, and egg quality traits of six Korean Native Chicken (KNC) crossbreds (RCYD, YCCF, YCCK, YDRC, YDCF, YDCK) from hatch to 32 weeks of age. A total of 480 birds were reared under standardized management during the growing (Day 1–Week 18) and laying (Week 18–32) phases. Productive parameters, including body weight, hen-day egg production (HDEP), egg mass, feed conversion ratio (FCR), and detailed external and internal egg quality traits, were recorded. Significant differences in body weight were observed among strains throughout the study (<i>P</i>&lt;0.001), with YDRC showing the greatest final weight. In contrast, HDEP, egg mass, and FCR did not differ among strains (<i>P</i>&gt;0.05), indicating comparable laying performance across the crossbreds. Strain-dependent variations in shell color, albumen height, and shell thickness were detected at week 24, while differences in shell color, albumen height, Haugh unit, and shell thickness were evident at week 32 (<i>P</i>&lt;0.05). Notably, YDCK and YCCK produced darker shells, whereas YDRC and YDCF exhibited superior albumen height and Haugh unit values. Overall, these findings reveal meaningful phenotypic variation among KNC crossbreds and provide a valuable foundation for targeted breeding, conservation programs, and the continued development of slow-growing egg-producing lines.