Effect of target trait in 2-trait selection index in two commercial lines of silkworm

In this study, genetic parameters of cocoon weight, cocoon shell weight and cocoon shell Percentage in two commercial lines (153 & 154), after three Generation, were Estimated. To achieve these goals, the REML Algorithm, and WOMBAT software were used. The base of selection was two conventional 2-trait index (based on cocoon weight- cocoon shell weight (A) and cocoon weight- cocoon shell percentage (B). for these goals were used from data in Iran Silkworm Research Center. Heritability's of cocoon weight, in two lines, in B method was upper than A method. In Mean Comparison of cocoon treats, between methods, to increase cocoon weight, a method was suggested. In cocoon shell weight, different between two methods, was no significant. Also between methods, to increase cocoon shell Percentage, B method was suggested. In production treats and Resistance, between methods in Hybrids, was no significant. Also the created of heterosis Percentage in two methods was same but means of cocoon shell Percentage between methods, was significant.