Imposing Restriction in Selection for Disproportionate Cut-Up Carcass Yield in an Experimental Flock of Broiler Chicken

Abstract

An experimental flock consisted of five broiler strains was used to evaluate the response to selection for breast and thighs weight with imposing restriction against low value portions of carcass over three generations. The linear models fitted for mean breast yield (BY), legs yield (LY), low value portions yield (LVPY), against generation showed an average improvement of 0.5%, 0.05%, and -0.2% per generation, respectively. The initial mean values for these traits were 21.6%, 22.8% and 29.1%, respectively. Genetic group showed significant influence on all the traits. Carcass weight (CW), breast weight (BW), legs weight (LW) and low value portions weight (LVPW) were significantly influenced by gender. Rate of feathering exhibited a significant impact on CW, BW, BY, and LW. Based on pooled data, the heritability estimate for CW, BW, LW and LVPW was 0.14, 0.16, 0.17 and 0.17, respectively. The estimate for corresponding yield traits was 0.11, 0.39, 0.10 and 0.31. Genetic correlations between absolute weight of carcass and cut-up parts were generally high (>0.85). However, the yield traits showed low correlations ranging from -0.05 to 0.22 with carcass weight. Imposing restriction for low value portions of carcass was found to be effective but merely through improvement in breast weight and yield. Negative influence of such a policy on thighs yield might be minimized using higher relative economic values for thighs weight in index construction process. Considering BY and LVPY instead of BW and LVPW in selection programs to create and improve particular lines could be more efficient based on their genetic characteristics and irrespective of constant lower variability in BY and LVPW.

Keywords

• breast
• broilers
• cut-up carcass
• legs
• restricted selection index