The new WBV evaluation system is now able to use all available data from crossbred Wagyu, including their genotypes, which leads to higher accuracy breeding values across the entire population.
For example, across F1, F2 and F3 Wagyu, there are approximately 14,000 animals with both genotype information and carcase performance records (such as marbling score, eye muscle area, rump fat and carcase weight). This data is now fully incorporated into the Wagyu genotype and phenotype reference population, which, together with Fullblood and Purebred records, forms the foundation of the WBV single-step evaluation.
Under the previous EBV system, performance data from crossbreds could be used, but it could not be combined with genomic information. As a result, only high-grade animals closely related to the Fullblood Black Wagyu population contributed genomically. The new WBV approach overcomes this limitation by integrating both performance and genomic data from crossbred Wagyu, substantially broadening the information base and improving the precision of the evaluation.
By using all available genomic information and performance information, we can calculate genomically influenced WBVs for the 14,000 crossbred animals with performance data recorded and compare them to the prior BREEDPLAN EBVs. The below example shows the prior Marble Score (MS) EBV based on performance data and pedigree on the x-axis plotted against the MS WBV based on performance data, pedigree and genomic information.
Figure legend: EBV to WBV change comparing 14,000 crossbred Wagyu MS EBVs with sire and performance data (x-axis BREEDPLAN EBV) to WBVs including sire, performance and genomic data (y-axis AWA WBVs).
The Figure shows that generally, there is a moderately strong relationship between EBVs and WBVs for crossbred animals for the Marble Score trait. However, there is significant variation around the line of best fit between EBVs and WBVs, meaning that including genomic information for crossbred animals in the genetic evaluation has a large impact on the breeding value estimate and this will impact the sire and dam of the crossbred progeny.
With this change to AWA’s genetic evaluation, we can now more effectively use the genomic information of the crossbred progeny to better attribute the crossbred animals genetic merit including for carcase performance to relatives up or down the pedigree.
Further, as in both the previous and current evaluations, performance data from crossbred Wagyu only contributes when breed effects are accounted for in the contemporary group formation. This ensures that crossbred animals are only compared against animals of the same crossbred type, maintaining meaningful comparisons.