Estimating the purebred-crossbred genetic correlation of body weight in broiler chickens with pedigree or genomic relationships

Pascal Duenk,Rachel Hawken,Piter Bijma,Yvonne C J Wientjes,Vivian P Breen,John M Henshall,Mario P L Calus

doi:10.1186/s12711-019-0447-9

Pascal Duenk, Rachel Hawken + Show 5 more

Open Access

https://doi.org/10.1186/s12711-019-0447-9

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Abstract

BackgroundIn pig and poultry breeding programs, the breeding goal is to improve crossbred (CB) performance, whereas selection in the purebred (PB) lines is often based on PB performance. Thus, response to selection may be suboptimal, because the genetic correlation between PB and CB performance (r_{pc}) is generally lower than 1. Accurate estimates of the r_{pc} are needed, so that breeders can decide if they should collect data from CB animals. r_{pc} can be estimated either from pedigree or genomic relationships, which may produce different results. With genomic relationships, the r_{pc} estimate could be improved when relationships between purebred and crossbred animals are based only on the alleles that originate from the PB line of interest. This work presents the first comparison of estimated r_{pc} and variance components of body weight in broilers, using pedigree-based or genotype-based models, where the breed-of-origin of alleles was either ignored or considered. We used genotypes and body weight measurements of PB and CB animals that have a common sire line.ResultsOur results showed that the r_{pc} estimates depended on the relationship matrix used. Estimates were 5 to 25% larger with genotype-based models than with pedigree-based models. Moreover, r_{pc} estimates were similar (max. 7% difference) regardless of whether the model considered breed-of-origin of alleles or not. Standard errors of r_{pc} estimates were smaller with genotype-based than with pedigree-based methods, and smaller with models that ignored breed-of-origin than with models that considered breed-of-origin.ConclusionsWe conclude that genotype-based models can be useful for estimating r_{pc}, even when the PB and CB animals that have phenotypes are closely related. Considering breed-of-origin of alleles did not yield different estimates of r_{pc}, probably because the parental breeds of the CB animals were distantly related.

Highlights

In pig and poultry breeding programs, the breeding goal is to improve crossbred (CB) performance, whereas selection in the purebred (PB) lines is often based on PB performance
Estimates of rpc and of the additive genetic covariance were larger for body weight measured around 35 days (BW35) than for body weight measured around 7 (BW7) (Fig. 2)
For BW7, the estimate of the additive genetic variance was smaller for PB performance than for CB performance, except with PED_BOA (Fig. 3)

Summary

Introduction

In pig and poultry breeding programs, the breeding goal is to improve crossbred (CB) performance, whereas selection in the purebred (PB) lines is often based on PB performance. Response to selection may be suboptimal, because the genetic correlation between PB and CB performance ( rpc ) is generally lower than 1. The rpc estimate could be improved when relationships between purebred and crossbred animals are based only on the alleles that originate from the PB line of interest. Response to selection in CB performance may be suboptimal, because the genetic correlation between PB and CB performance ( rpc ) is generally lower than 1 [1,2,3]. When these data are available, rpc can be estimated with a pedigree-based animal or sire model [13] Such models treat PB and CB performance as correlated traits and use a pedigree-based relationship matrix ( A ) to link PB and CB observations [1]. In practice, pedigree information is often not recorded in CB populations and the number of sires that have both PB and CB offspring with phenotypes may be limited

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