title: Evaluation of the effect and profitability of gene-assisted selection in pig breeding system.
abstract: OBJECTIVE
  To evaluate the effect and profitability of using the quantitative trait loci (QTL)-linked direct marker (DR marker) in gene-assisted selection (GAS).
  
  
  METHODS
  Three populations (100, 200, or 300 sows plus 10 boars within each group) with segregating QTL were simulated stochastically. Five economic traits were investigated, including number of born alive (NBA), average daily gain to 100 kg body weight (ADG), feed conversion ratio (FCR), back fat at 100 kg body weight (BF) and intramuscular fat (IMF). Selection was based on the estimated breeding value (EBV) of each trait. The starting frequencies of the QTL's favorable allele were 0.1, 0.3 and 0.5, respectively. The economic return was calculated by gene flow method.
  
  
  RESULTS
  The selection efficiency was higher than 100% when DR markers were used in GAS for 5 traits. The selection efficiency for NBA was the highest, and the lowest was for ADG whose QTL had the lowest variance. The mixed model applied DR markers and obtained higher extra genetic gain and extra economic returns. We also found that the lower the frequency of the favorable allele of the QTL, the higher the extra return obtained.
  
  
  CONCLUSIONS
  GAS is an effective selection scheme to increase the genetic gain and the economic returns in pig breeding.
authors.affiliation: College of Animal Science, South China Agricultural University, Guangzhou, China.
authors.forename: Ya-Lan
authors.initials: YL
authors.lastname: Li
authors.forename: Qin
authors.initials: Q
authors.lastname: Zhang
authors.forename: Yao-Sheng
authors.initials: YS
authors.lastname: Chen
mesh_terms: D000818:Animals; D001947:Breeding / Q000191:economics / Q000379:methods*; D005819:Genetic Markers; D008957:Models, Genetic; D040641:Quantitative Trait Loci; D012641:Selection, Genetic; D013552:Swine
chemical_list: D005819:Genetic Markers