Effects of mass selection on egg production on some reproductive traits in Japanese quail

Most of the selection studies in Japanese quail have focused on high body weight or short-term egg production. The effect of selection on long-term egg production is not well known. Japanese quail lines were subjected to phenotypic mass selection in different ways over 11 generations and a control group was reproduced by random mating. A high body weight line (HL), a low body weight line (LL) (based on 5-week body weight), a line (L) subjected to selection for egg production (120 day) and a control line (C) were used. Age at sexual maturity, egg weight, total number of eggs for 45 weeks and body weight of the lines were determined. A nonlinear regression analysis using the Grossman egg production function was used for the comparison of egg productions of the flocks. Selection for low body weight delayed age at sexual maturity and reduced egg weight. On the other hand, selection for high body weight increased egg weight and peak production level. The highest value for the b(4)-parameter of the Grossman Model was determined for the HL line in which the fastest decrease in egg production occurred after the peak production. The highest value for persistency parameter (p) of the model was found for the L line where the quail had high egg production for a longer period. The selection for high body weight led to a reduction in egg production by 13.5%. Eleven generations of selection for increasing 120 days egg production resulted in an increase by 5.05%. The use of a selection criterion estimating total egg production better would make selection more efficient and improve egg production. Determination of the monthly egg yield, which has a high genetic correlation with total egg production, is suggested for this purpose.