02627naa a2200253 a 450000100080000000500110000800800410001902200140006002400270007410000200010124501330012126000090025452018490026365000330211265300230214565300220216865300230219070000210221370000160223470000150225070000160226570000160228177300760229710538622015-12-02       2015    bl uuuu     u00u1 u    #d  a0931-26687 a10.1111/jbg.121612DOI1 aFRAGOMENI, B.O.  aUse of genomic recursions and algorithm for proven and young animals for single-step genomic BLUP analyses - a simulation study.  c2015  aABSTRACT.  The purpose of this study was to examine accuracy of genomic selection via single-step genomic BLUP (ssGBLUP) when the direct inverse of the genomic relationship matrix (G) is replaced by an approximation of G1 based on recursions for young genotyped animals conditioned on a subset of proven animals, termed algorithm for proven and young animals (APY). With the efficient implementation, this algorithm has a cubic cost with proven animals and linear with young animals. Ten duplicate data sets mimicking a dairy cattle population were simulated. In a first scenario, genomic information for 20k genotyped bulls, divided in 7k proven and 13k young bulls, was generated for each replicate. In a second scenario, 5k genotyped cows with phenotypes were included in the analysis as young animals. Accuracies (average for the 10 replicates) in regular EBV were 0.72 and 0.34 for proven and young animals, respectively. When genomic information was included, they increased to 0.75 and 0.50. No differences between genomic EBV (GEBV) obtained with the regular G1 and the approximated G1 via the recursive method were observed. In the second scenario, accuracies in GEBV (0.76, 0.51 and 0.59 for proven bulls, young males and young females, respectively) were also higher than those in EBV (0.72, 0.35 and 0.49). Again, no differences between GEBV with regular G1 and with recursions were observed. With the recursive algorithm, the number of iterations to achieve convergence was reduced from 227 to 206 in the first scenario and from 232 to 209 in the second scenario. Cows can be treated as young animals in APY without reducing the accuracy. The proposed algorithm can be implemented to reduce computing costs and to overcome current limitations on the number of genotyped animals in the ssGBLUP method.  © 2015 Blackwell Verlag GmbH  aMEJORAMIENTO GENETICO ANIMAL  aGENETIC EVALUATION  aGENOMIC SELECTION  aSINGLE-STEP METHOD1 aLOURENCO, D.A.L.1 aTSURUTA, S.1 aMASUDA, Y.1 aAGUILAR, I.1 aMISZTAL, I.  tJournal of Animal Breeding and Genetics, 2015gv.132, no.5, p. 340-345.