Study of the effect of increasing markers density on the accuracy of genomic evaluation using rrBLUP

Genomic selection is a method to predict the breeding values of individuals using a large number of single nucleotide polymorphism markers. The cost of the high-density marker panel genotyping is very high, which prevents the widely application of genomic selection. The present simulation study was carried out to evaluate the use of low to medium marker density panels to predict direct genomic values. In this study, a trait with heritability of 0.10, 0.20, and 0.40 was simulated. The simulated genome was consisted of 25 outosomes with the same distance (1morgan). Different marker density (12.5, 27.5 and 50 k) and 125, 250, 500 and 1000 random distributed QTL were simulated. The least square means of genomic accuracy varied between the different levels of heritability and the different marker density (P<0.05)­. For low heritable trait (10℅), increasing the markers density had no effect on genomic accuracy with low (125) or high (1000) number of QTL, but did with the moderate number of QTLs (250 and 500 QTLs). The results showed that along with increasing in the number of markers, genomic accuracy was not changed in traits with medium heritability (20℅). For high heritable trait (40℅), increasing the marker density had no effect on genomic accuracy whit the moderate to high QTL density (250, 500 or 1000 QTLs), but but it increased the accuracy with low number of QTLs (125 QTLs).