title: Response and inbreeding from a genomic selection experiment in layer chickens.
abstract: BACKGROUND
  Genomic selection (GS) using estimated breeding values (GS-EBV) based on dense marker data is a promising approach for genetic improvement. A simulation study was undertaken to illustrate the opportunities offered by GS for designing breeding programs. It consisted of a selection program for a sex-limited trait in layer chickens, which was developed by deterministic predictions under different scenarios. Later, one of the possible schemes was implemented in a real population of layer chicken.
  
  
  METHODS
  In the simulation, the aim was to double the response to selection per year by reducing the generation interval by 50 %, while maintaining the same rate of inbreeding per year. We found that GS with retraining could achieve the set objectives while requiring 75 % fewer reared birds and 82 % fewer phenotyped birds per year. A multi-trait GS scenario was subsequently implemented in a real population of brown egg laying hens. The population was split into two sub-lines, one was submitted to conventional phenotypic selection, and one was selected based on genomic prediction. At the end of the 3-year experiment, the two sub-lines were compared for multiple performance traits that are relevant for commercial egg production.
  
  
  RESULTS
  Birds that were selected based on genomic prediction outperformed those that were submitted to conventional selection for most of the 16 traits that were included in the index used for selection. However, although the two programs were designed to achieve the same rate of inbreeding per year, the realized inbreeding per year assessed from pedigree was higher in the genomic selected line than in the conventionally selected line.
  
  
  CONCLUSIONS
  The results demonstrate that GS is a promising alternative to conventional breeding for genetic improvement of layer chickens.
authors.affiliation: Department of Animal Science, Iowa State University, Ames, IA, 50011-3150, USA. awolc@iastate.edu.|Hy-Line International, Dallas Center, IA, 50063, USA. awolc@iastate.edu.
authors.forename: Anna
authors.initials: A
authors.lastname: Wolc
authors.affiliation: Department of Animal Science, Iowa State University, Ames, IA, 50011-3150, USA. Honghua.Zhao@pioneer.com.
authors.forename: Honghua H
authors.initials: HH
authors.lastname: Zhao
authors.affiliation: Hy-Line International, Dallas Center, IA, 50063, USA. JArango@hyline.com.
authors.forename: Jesus
authors.initials: J
authors.lastname: Arango
authors.affiliation: Hy-Line International, Dallas Center, IA, 50063, USA. PSettar@hyline.com.
authors.forename: Petek
authors.initials: P
authors.lastname: Settar
authors.affiliation: Hy-Line International, Dallas Center, IA, 50063, USA. JFulton@hyline.com.
authors.forename: Janet E
authors.initials: JE
authors.lastname: Fulton
authors.affiliation: Hy-Line International, Dallas Center, IA, 50063, USA. NOSullivan@hyline.com.
authors.forename: Neil P
authors.initials: NP
authors.lastname: O'Sullivan
authors.affiliation: Lohmann Tierzucht GmbH, 27472, Cuxhaven, Germany. preisinger@ltz.de.
authors.forename: Rudolf
authors.initials: R
authors.lastname: Preisinger
authors.affiliation: agn Genetics GmbH, Börtjistrasse 8b, 7260, Davos, Switzerland. stricker@genetics-network.ch.
authors.forename: Chris
authors.initials: C
authors.lastname: Stricker
authors.affiliation: Department of Animal Science, Iowa State University, Ames, IA, 50011-3150, USA. dhabier@gmail.com.
authors.forename: David
authors.initials: D
authors.lastname: Habier
authors.affiliation: Department of Animal Science, Iowa State University, Ames, IA, 50011-3150, USA. rohan@iastate.edu.
authors.forename: Rohan L
authors.initials: RL
authors.lastname: Fernando
authors.affiliation: Department of Animal Science, Iowa State University, Ames, IA, 50011-3150, USA. dorian@iastate.edu.
authors.forename: Dorian J
authors.initials: DJ
authors.lastname: Garrick
authors.affiliation: Department of Animal Science, Iowa State University, Ames, IA, 50011-3150, USA. sjlamont@iastate.edu.
authors.forename: Susan J
authors.initials: SJ
authors.lastname: Lamont
authors.affiliation: Department of Animal Science, Iowa State University, Ames, IA, 50011-3150, USA. jdekkers@iastate.edu.
authors.forename: Jack C M
authors.initials: JC
authors.lastname: Dekkers
mesh_terms: D000818:Animals; D002645:Chickens / Q000235:genetics* / Q000502:physiology; D008957:Models, Genetic; D010375:Pedigree; D010641:Phenotype; D040641:Quantitative Trait Loci; D012641:Selection, Genetic; D000068618:Selective Breeding / Q000235:genetics*