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Journal of Animal Science Abstract - Animal Genetics

Effect of different genomic relationship matrices on accuracy and scale1


This article in JAS

  1. Vol. 89 No. 9, p. 2673-2679
    Received: Sept 29, 2010
    Accepted: Mar 21, 2011
    Published: December 4, 2014

    2 Corresponding author(s):

  1. C. Y. Chen 23,
  2. I. Misztal*,
  3. I. Aguilar*†,
  4. A. Legarra and
  5. W. M. Muir§
  1. Department of Animal and Dairy Science, University of Georgia, Athens 30602-2771;
    Instituto Nacional de Investigación Agropecuaria, Las Brujas 90200, Uruguay;
    INRA, UR631 Station d’Amélioration Génétique des Animaux (SAGA), BP 52627, 32326 Castanet-Tolosan, France; and
    Department of Animal Science, Purdue University, West Lafayette, IN 47907-1151



Phenotypic data on BW and breast meat area were available on up to 287,614 broilers. A total of 4,113 birds were genotyped for 57,636 SNP. Data were analyzed by a single-step genomic BLUP (ssGBLUP), which accounts for all phenotypic, pedigree, and genomic information. The genomic relationship matrix (G) in ssGBLUP was constructed using either equal (0.5; GEq) or current (GC) allele frequencies, and with all SNP or with SNP with minor allele frequencies (MAF) below multiple thresholds (0.1, 0.2, 0.3, and 0.4) ignored. Additionally, a pedigree-based relationship matrix for genotyped birds (A22) was available. The matrices and their inverses were compared with regard to average diagonal (AvgD) and off-diagonal (AvgOff) elements. In A22, AvgD was 1.004 and AvgOff was 0.014. In GEq, both averages decreased with the increasing thresholds for MAF, with AvgD decreasing from 1.373 to 1.020 and AvgOff decreasing from 0.722 to 0.025. In GC, AvgD was approximately 1.01 and AvgOff was 0 for all MAF. For inverses of the relationship matrices, all AvgOff were close to 0; AvgD was 2.375 in A22, varied from 11.563 to 12.943 for GEq, and increased from 8.675 to 12.859 for GC as the threshold for MAF increased. Predictive ability with all GEq and GC was similar except that at MAF = 0.4, they declined by 0.01 for BW and improved by 0.01 for breast meat area. Compared with BLUP, EBV in the ssGBLUP were, on average, increased by up to 1 additive SD greater with GEq and decreased by 2 additive SD less with GC. Genotyped animals were biased upward with GEq and downward with GC. The biases and differences in EBV could be controlled by adding a constant to GC; they were eliminated with a constant of 0.014, which corresponds to AvgOff in A22. Unbiased evaluation in the ssGBLUP may be obtained with GC scaled to be compatible with A22. The reduction of SNP with small MAF has a small effect on the real accuracy, but it may falsely increase the estimated accuracies by inversion.

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Copyright © 2011. American Society of Animal Science