Relationship between egg quality traits and hatchability in pure-line white layer strains

Hatchability is a very important trait in a breeding program which has a great economical impact on franchise hatcheries. The variability between and within strains raises the question whether reproductive performance can be improved by selection within lines. The aim of this study is to analyse the genetic background of the hatchability and its correlations between egg quality and production traits. Data from two pure-bred female lines at an age of 45 weeks of an LSL commercial breeding program were used. The heritability for reproductive traits was between low and medium: 0.13 and 0.15 for fertility, as well as 0.27 and 0.29 for hatchability respectively. The correlation between hatchability and egg weight is negative with rg= -0.43 to -0.52. The same with the albumen height with rg= -0.25 to 0.42. There was a negative but not significant correlation with body weight. On the contrary, the correlation with yolk proportion was slightly positive (rg= +0.08 to +0.39), and the correlation with egg production (rg= -0.01 to +0.28). For egg quality traits like shell strength and shape index (length/width), positive correlations ranging from rg= +0.14 to +0.32 were estimated.