Genetic and phenotypic response to selection in various traits of IWH and IWI strains of White Leghorn under long term selection

Abstract

 A study was undertaken on male (IWH) and female (IWI) line of White leghorn completing 29 generation of selection. The average age at sexual maturity declined significantly in both the strains with the estimates of –1.404 and –1.28 days in IWH and IWI strains respectively on phenotypic scales. Corresponding estimates on genetic scales were –0.47 and –0.35 days per generation in IWH and IWI strains. The change in the average response per generation for egg weight at 28 ^th and and  40 ^th wk of age in both the selected strains were mostly non-significant except for significant negative genetic association of 40^th  weeks egg production with egg weight at 40 week of age in IWI strain.. Egg production ( 40^th wk) improved significantly in the both the selected strains with the estimates of 0.880.15 and 0.690.15 eggs per generation in IWH and IWI strains on genetic scale.  
. Average responses per generation for various economic traits observed at 64th wks of age revealed that body weight (BW-64) declined non-significantly in both the selected strains except for positive but non significant  response for 64^th  wk body weight on phenotypic scale.