Mapping Quantitative Trait Loci underlying Kleiber ratio and identification of their mode of action in an F2 population of Japanese quail (Coturnix coturnix japonica)

A three-generation resource population was developed by using two distinct Japanese quail strains, wild and white to map quantitative trait loci underlying Kleiber ratio, an indirect criterion of feed efficiency. Eight pairs of white (S) and wild (W) birds were crossed reciprocally and 34 F1 birds were produced. The F1 birds were intercrossed to generate 422 F2 offspring. All of the birds from three generations (472 birds) were genotyped for eight microsatellite markers on chromosome 1. Liveweight data from hatch to 5 weeks of age were collected on the F2 birds. QTL analysis was conducted applying the line-cross model and the least-squares interval mapping approach. The results indicated QTL affecting Kleiber ratio for 1 to 2, 3 to 4, 4 to 5 and hatch to 5 weeks of age on chromosome 1. The F2 phenotypic variance explained by the detected QTL effects ranged from 0.8 to 3.7 for different traits. Modeling both additive and dominance QTL effects revealed QTL with significant additive mode of action. However, there was no evidence for imprinting (parent-of-origin) effects.