Improving hatchability in white egg layer strains through breeding

Hatchability is of considerable economic importance for all hatcheries and therefore must be given appropriate attention in breeding programs for commercial layers. The variability between and within strains will tell us whether reproductive performance can be improved by selection within specific lines. The aim of this study was to analyse the genetic variation of hatchability and correlations with production traits. Data collected from two pure-bred female lines (LSL) at 45-46 weeks of age were used. Estimated heritabilities were low (h² = 0.13 and 0.15) for fertility, but moderately high (h² = 0.27 and 0.30) for hatch of ‘fertile’ eggs (eggs transferred at 18 days). Hatchability was negatively correlated with egg weight (r g = -0.43 to -0.52) and albumen height (r g = -0.25 to -0.42). Favourable correlations were found with egg production (rg = -0.01 to +0.28), percentage yolk (r g = +0.08 to +0.39) and some shell quality traits like shape index and breaking strength (r g = +0.14 to +0.32), but not with dynamic stiffness (r g = -0.08 to -0.17). Hatch of fertile eggs has sufficient genetic variation in these White Leghorn lines to expect improvement by within-line selection, especially if supported by a reduction in total egg weight and selection for higher egg production, yolk percentage and shell breaking strength.