Relationship among productivity and egg traits in the Japanese quail hen

The influence of the 6th week body weight (point of lay) and lay-period on the relationship among egg production and egg quality traits was investigated in Coturnix coturnix japonica (Japanese quail) hens. One hundred and eighty quail birds at six weeks were randomized into three body weight groups (123-130, 131-137, and 138-144 g), each consisting of six replicates of 10 birds per replicate. The body weight groupings interacted with three lay periods to give a 3 x 3 factorial treatment design. All replicates were fed common diets from the 6th week to 15th week. Daily feed intake (DFI), average body weight (ABW) average egg weight (AEW), hen day egg production (HDP), feed conversion ratio (FCR), albumen weight (AWT) and yolk weight (YWT) were recorded throughout the experiment by standard experimental procedures. Data were analyzed with the Multiple Linear Regression (MLR) procedures of SAS. Standardized regression analyses revealed significant and positive relationship between DFI/AEW (b=0.819, R2= 0.615, P=0.001) in the 138-144 body weight group; positive relationship between AWT/AEW, ABW (b=0.671-1.514, d=0.119-0.269, R2 ≥ 0.671, P=0.001) in all body weight groups and lay periods; and a negative relationship between HDP/FCR, AEW (b= -0.791 to -1.373, d= -0.222 to -0.624, R2 ≥ 0.827, P=0.001) in the last two body weight groups and lay periods respectively. The relationship between daily feed intake and egg weight was positive in mid body weight. Albumen weight/average egg weight and average body weight were positively related, but hen day production/feed conversion ratio, and average egg weight, albumen weight and feed conversion ratio were negatively related. These relationships are of practical importance for management, breeding and improvement of quail production traits.