The effect of incomplete sire pedigree on prediction of breeding value and estimation of the genetic trend of weaning weight and average daily gain in sheep

In order to study on the effect of incomplete sire''s pedigree on the prediction of breeding value and estimation of genetic trend، two quantitative traits such as weaning weight and average daily gain with heritabilities 0. 15 and 0. 30 were simulated. Phenotypic، genetic and environmental correlations were assumed 0. 5. Resulted data files with different proportion of missed sire pedigree (0-100) were analyzed using bivariate animal model. Breeding value means for WW and ADG reduced from 1. 61 to 0. 55 and 69. 48 to 24. 68 with 10 percent random deletion of sire pedigree. This parameter was also decreased to 1. 47 and 63. 67 for WW and ADG respectively، with 10 percent sequential deletion of sire pedigree. Decreasing genetic trend of ADG were 61. 32 and 0. 66 percent for 10 percent random and sequential deletion of sire pedigree، respectively. This reduction for WW was also 63. 43 and 0 percent. Generally، the incompleteness of sire pedigree affected the accuracy of breeding value prediction and genetic trend and based on the rate of sire pedigree deletion، the part of accuracy of breeding value prediction were lost. Then، the genetic tend estimated using real data should be analyzed based on the rate of completeness of sire pedigree.