Inheritance of mortality and its association with economic traits in layer chickens

Heritabilities and correlations of mortality at different stages (brooding, growing, and laying house) were estimated on a total of 6941 birds of two selected strains of White Leghorn. The strain having higher mortality from day old to 40 weeks of age was characterized by early sexual maturity. higher egg production, egg mass and body weights. Heritabilities for mortality were low (0.065 to 0.159). The genetic correlations among mortality at ditferent stages were inconsistent between the two strains. Brooding and growing house mortality had negative genetic correlation with age at sexual maturity. Laying house mortality had negative genetic correlations (−0.52 and -0.55) with hen-house production.