Developing a Reduced SNP Panel for Low-cost Genotyping in Beef Cattle

The objective of this study was to develop a low-density reduced SNP panel (RP) that could capture most of the predictive ability of a 50K panel for six important traits (birth, weaning and yearling weights; calving ease direct; marbling; and rib eye area) in beef cattle. More than 15,000 animals from six cattle breeds genotyped with 50K were used to select markers highly associated with target traits. Accuracies of direct genomic breeding values (DGV) were calculated for 3 independent validation populations using either 50K or RP. Accuracies of DGV obtained from RP were comparable with those obtained from 50K (\u3e75% predictive ability of 50K) while the size of RP i

Accuracies of Genomic Prediction in Beef Cattle

The objective of this study was to derive and evaluate the accuracies of molecular breeding values (MBV) for economically relevant traits for commercial implementation in several beef cattle breeds. We developed MBV forHereford, Red Angus and Simmental breeds. Accuracies of MBV ranged from 0.18 to 0.45 in Hereford, 0.37 to 0.85 in Red Angus, and from 0.29 to 0.65 in Simmental using within breed genomic predictions. Single breed genomic predictions had no utility when applied to other breeds. However, the accuracies of MBV improved for some breeds when predictions were derived using multi-breed reference populations. These results have now been implemented as routine predictions for breeders of American Hereford, American Red Angus and American Simmental beef cattle. Similar findings will soon be extended to other breeds

Impact of Pedigree Information and Genome Assembly Errors on Inference of SNP Haplotypes in Cattle

The impact of pedigree information and SNP location determined from either the UMD3.1 genome sequence assembly or the USDA-AIPL map on phasing accuracy were evaluated for 2 chromosomes in 2,778 parent verified Angus sire/offspring pairs. DAGPHASE (Druet and Georges, 2010), using a single generation pedigree was superior to BEAGLE software (Browning and Browning, 2007) for phasing. Results based on USDA-AIPL map are closer to expectation than those based on UMD3.1, but the difference is not significant. Recombination hotspots weredetected near 4 and 82Mb on BTA14, and near 25Mb on BTA15

Accuracy of direct genomic breeding values for nationally evaluated traits in US Limousin and Simmental beef cattle

BACKGROUND: In national evaluations, direct genomic breeding values can be considered as correlated traits to those for which phenotypes are available for traditional estimation of breeding values. For this purpose, estimates of the accuracy of direct genomic breeding values expressed as genetic correlations between traits and their respective direct genomic breeding values are required. METHODS: We derived direct genomic breeding values for 2239 registered Limousin and 2703 registered Simmental beef cattle genotyped with either the Illumina BovineSNP50 BeadChip or the Illumina BovineHD BeadChip. For the 264 Simmental animals that were genotyped with the BovineHD BeadChip, genotypes for markers present on the BovineSNP50 BeadChip were extracted. Deregressed estimated breeding values were used as observations in weighted analyses that estimated marker effects to derive direct genomic breeding values for each breed. For each breed, genotyped individuals were clustered into five groups using K-means clustering, with the aim of increasing within-group and decreasing between-group pedigree relationships. Cross-validation was performed five times for each breed, using four groups for training and the fifth group for validation. For each trait, we then applied a weighted bivariate analysis of the direct genomic breeding values of genotyped animals from all five validation sets and their corresponding deregressed estimated breeding values to estimate variance and covariance components. RESULTS: After minimizing relationships between training and validation groups, estimated genetic correlations between each trait and its direct genomic breeding values ranged from 0.39 to 0.76 in Limousin and from 0.29 to 0.65 in Simmental. The efficiency of selection based on direct genomic breeding values relative to selection based on parent average information ranged from 0.68 to 1.28 in genotyped Limousin and from 0.51 to 1.44 in genotyped Simmental animals. The efficiencies were higher for 323 non-genotyped young Simmental animals, born after January 2012, and ranged from 0.60 to 2.04. CONCLUSIONS: Direct genomic breeding values show promise for routine use by Limousin and Simmental breeders to improve the accuracy of predicted genetic merit of their animals at a young age and increase response to selection. Benefits from selecting on direct genomic breeding values are greater for breeders who use natural mating sires in their herds than for those who use artificial insemination sires. Producers with unregistered commercial Limousin and Simmental cattle could also benefit from being able to identify genetically superior animals in their herds, an opportunity that has in the past been limited to seed stock animals