Identification of quantitative trait loci associated with egg quality, egg production, and body weight in an F2 resource population of chickens¹

Abstract

Egg production and egg quality are complex sex-limited traits that may benefit from the implementation of marker-assisted selection. The primary objective of the current study was to identify quantitative trait loci (QTL) associated with egg traits, egg production, and body weight in a chicken resource population. Layer (White Leghorn hens) and broiler (Cobb-Cobb roosters) lines were crossed to generate an F2 population of 508 hens over seven hatches. Phenotypes for 29 traits (weekly body weight from hatch to 6 weeks, egg traits including egg, albumen, yolk, and shell weight, shell thickness, shell puncture score, percentage of shell, and egg shell colour at 35 and 55 weeks of age, as well as egg production between 16 and 55 weeks of age) were measured in hens of the resource population. Genotypes of 120 microsatellite markers on 28 autosomal groups were determined, and interval mapping was conducted to identify putative QTL. Eleven QTL tests representing two regions on chromosomes 2 and 4 surpassed the 5% genome-wise significance threshold. These QTL influenced egg colour, egg and albumen weight, percent shell, body weight, and egg production. The chromosome 4 QTL region is consistent with multiple QTL studies that define chromosome 4 as a critical region significantly associated with a variety of traits across multiple resource populations. An additional 64 QTL tests surpassed the 5% chromosome-wise significance threshold.

W chromosome expression responds to female-specific selection

“…traits (22,31,32), or for marker-assisted selection for industrial egg production. However, CNV does not explain the majority of variation in expression.…”

Phenotypic characterization of chicken inbred lines that differ extremely in growth, body composition and egg production traits

“…Therefore, genetic studies have been performed to map genes and genomic loci that affect growth, body composition (MCELROY et al 2006, CAMPOS et al 2009, and reproduction traits (TUISKULA-HAAVISTO et al 2002, SASAKI et al 2004, HANSEN et al 2005, SCHREIWEIS et al 2006. If inbred lines of diverse selection lines are used for gene mapping experiments, the probability is very high that different alleles contributing to different traits segregate in the mapping population, and thus these genetic differences can be identified.…”

Polymorphisms associated with egg number at 300 days of age in chickens

“…QTL influencing the egg number from 16 to 25 weeks of age was mapped to chromosome 4, whereas QTL related to the egg number between 18 and 40 weeks of age were mapped to chromosome 8, Z and 11 (Tuiskula-Haavisto et al, 2002Schreiweis et al, 2006). Additionally, the QTL region between 87 and 105 cM of the Z chromosome was found to affect the egg number from 18 to 40 weeks of age and from 41 to 60 weeks of age, the average egg weight of these two periods, as well as the age of first egg (AFE) (Tuiskula-Haavisto et al, 2002;Sasaki et al, 2004).…”

“…Many studies have been performed to identify QTL regulating chicken egg number (Hansen et al, 2005;Schreiweis et al, 2006;Chatterjee et al, 2010). QTL influencing the egg number from 16 to 25 weeks of age was mapped to chromosome 4, whereas QTL related to the egg number between 18 and 40 weeks of age were mapped to chromosome 8, Z and 11 (Tuiskula-Haavisto et al, 2002Schreiweis et al, 2006).…”