Performance evaluation and heterosis for economic traits of White Leghorn under reciprocal recurrent selection

The mean performance of pure lines and per cent heterosis for production traits in reciprocal crosses between two lines (IWH & IWI) of White Leghorn undergoing reciprocal recurrent selection for part period egg production up to 280 days of age were studied over six consecutive generations. The crosses were, in general, superior to their mid-parent values over the generations for egg production, 20 and 40 week body weights, but inferior for egg weight and age at sexual maturity. The average heterosis for egg production to 280 days of age, egg weight, age at sexual maturity, 20 and 40 week body weight varied from 1.24 to 19.00%, −4.85 to 6.11%, −6.01 to 0.13%, −0.26 to 9.38% and −8.47 to 12.01%, respectively over the generations. The reciprocal crosses differed in performance for all the traits suggesting the existence of maternal/sex-linked effects. The superiority of HI cross over respective IH crosses consistently across the generations suggested the use of IWH as sire and IWI as dam line for the production of a commercial layer strain.