Estimating the purebred-crossbred genetic correlation for uniformity of eggshell color in laying hens.

Han A Mulder,Julien Fablet,Jeroen Visscher

doi:10.1186/s12711-016-0212-2

Abstract

BackgroundUniformity of eggs is an important aspect for retailers because consumers prefer homogeneous products. One of these characteristics is the color of the eggshell, especially for brown eggs. Existence of a genetic component in environmental variance would enable selection for uniformity of eggshell color. Therefore, the objective of this study was to quantify the genetic variance in environmental variance of eggshell color in purebred and crossbred laying hens, to estimate the genetic correlation between environmental variance of eggshell color in purebred and crossbred laying hens and to estimate genetic correlations between environmental variance at different times of the laying period.MethodsWe analyzed 167,651 and 79,345 eggshell color records of purebred and crossbred laying hens, respectively. The purebred and crossbred laying hens originated mostly from the same sires. Since eggshell color records of crossbred laying hens were collected per cage, these records could be related only to cage and sire family. A double hierarchical generalized linear sire model was used to estimate the genetic variance of the mean of eggshell color and its environmental variance. Approximate standard errors for heritability and the genetic coefficient of variation for environmental variance were derived.ResultsThe genetic variance in environmental variance at the log scale was equal to 0.077 and 0.067, for purebred and crossbred laying hens, respectively. The genetic coefficient of variation for environmental variance was equal to 0.28 and 0.26, for purebred and crossbred laying hens, respectively. A genetic correlation of 0.70 was found between purebred and crossbred environmental variance of eggshell color, which indicates that there is some reranking of sires for environmental variance of eggshell color in purebred and crossbred laying hens. Genetic correlations between environmental variance of eggshell color in different laying periods were generally higher than 0.85, except between early laying and mid or late laying periods.ConclusionsOur results indicate that genetic selection can be efficient to improve uniformity of eggshell color in purebreds and crossbreds, ideally by applying combined crossbred and purebred selection. This methodology can be used to estimate genetic correlations between purebred and crossbred lines for uniformity of other traits and species.Electronic supplementary materialThe online version of this article (doi:10.1186/s12711-016-0212-2) contains supplementary material, which is available to authorized users.

Highlights

Uniformity of eggs is an important aspect for retailers because consumers prefer homogeneous products
The genetic standard deviation expressed relative to the mean, i.e. the genetic coefficient of variation (GCVVe), is ~0.3 [4], which indicates that if the selection response in VE is equal to one genetic standard deviation, VE would change by 30 %
Permanent environmental effects explained a large proportion of the phenotypic variance even after subtracting three quarters of the genetic variance (16.7 %), i.e. the additive genetic variance due to dam and Mendelian sampling

Summary

Introduction

Uniformity of eggs is an important aspect for retailers because consumers prefer homogeneous products. One of these characteristics is the color of the eggshell, especially for brown eggs. Existence of a genetic component in environmental variance would enable selection for uniformity of eggshell color. Mulder et al Genet Sel Evol (2016) 48:39 does not necessarily make the eggs uniform and to date, there is no evidence that selection for more uniform brown eggs is possible. Selection for more uniform brown eggs requires the presence of genetic variation in the uniformity of this trait. Eggshell color is measured several times during a laying period, which provides the opportunity to study genetic variation in VE of eggshell color at different times of the egg laying period. Genetic variation in VE may differ between laying periods and genetic correlations between VE in different laying periods may differ from 1

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