Influence of age of the hen and selection on egg production and egg quality characteristics of Japanese quails

The study was conducted on a growth line, a control line and a dam line of Japanese quails. The growth line had consistently lower hen-day and hen-house production, delayed age at 50% production, took long time to attain peak production, lower peak production, short stability period of production, low egg production in the entire laying period and high laying-house mortality. Performance of dam line was intermediate for egg production. Egg weight improved by 14.5% from 10 to 24 weeks of age and then deteriorated by about 6% upto 32 weeks of age and the length and width of eggs at different ages paralleled with the change in egg weight. Shape index and Specific gravity were significantly (p≤0.01) high during earlier period of laying. Haugh Unit Score (HUS %) varied significantly at different ages. Albumen, yolk and shell weight comprised 62.8, 29.6 and 7.5% of egg weight respectively. Albumen and yolk weight % were high at 10 and 24 weeks of age respectively and yolk quality as measured by yolk height (mm), yolk diameter and yolk index improved with age. The three lines differed significantly (p≤0.01) for egg weight and shape index. Due to the effect of selection the growth and dam-line had significantly (p≤0.01) high weight, length and width of eggs, albumen height (mm) and HUS % but the control line had higher shape index and specific gravity. The differences among the lines were statistically significant for physical egg-composition traits. The selection employed for improvement of body weight in the growth line resulted in deterioration of egg production performance, shell quality, yolk and shell weight % and lead to improvement in egg weight, albumen and yolk quality. These traits need to be incorporated in the selection based on egg production performance along with body weight selection.