Conservation and Genetic Evaluation of Exotic Chicken Germplasms and Their Crossbreds Under Intensive Rearing in Bangladesh

This study aimed to enhance the conservation and productivity of four purebred chicken lines (White Leghorn, WL; Rhode Island Red, RIR; White Rock, WR; and Barred Plymouth Rock, BPR), as well as their crossbreds with Desi chickens. For crossbreeding, two of the pure lines, BPR and RIR, were used to develop three crossbred combinations: Cross 1 (BPR × Desi), Cross 2 (Desi × RIR), and Cross 3 (RIR × Desi, reciprocal to Cross 2). A total of 4,000-day-old chicks were selected using a multi-trait index incorporating age at first egg (days), 40th week body weight (g), egg production rate measured between 168 and 280 days of age (%), and 40th week egg weight (g). Crossbreds were assessed for growth performance, reproductive traits, feed efficiency, and carcass characteristics. Selection in the pure lines achieved significant genetic gains, with a selection response of 2.81% for egg production in WR and 1.96 g for egg weight in WL, while maintaining high genetic diversity (effective population size, Ne > 80) and minimal inbreeding (ΔF = 0.006). In crossbred evaluation, Cross 3 showed significantly higher (P