Wagyu Genetics Collaboration Research Project

Summary

​Performance, pedigree and genotype data on approximately 2-3,000 Wagyu predominantly Fullblood animals was collected, including data collected using the Japanese Digital Camera Image Analysis methodology. The lack of a universal ID system added significant project coordination costs, and will if not rectified, add costs in any project seeking to use detailed carcase data in genetic evaluation. Traditional pedigree analysis has demonstrated that it is possible to collect and genetically analyse detailed carcase information on commercial Wagyu animals, with results showing: carcase marbling, whether measured using the camera or via Ausmeat score, is moderately to highly heritable (current estimate for heritability is 0.52 for CMAU and 0.35 for CCMP); Carcase Marbling Fineness Index is moderately-highly heritable (0.50); the two measures of carcase marbling (CCMP and CMAU) are genetically essentially the same trait (genetic correlation = 1.00); and Carcase Eye Muscle Area and Camera Rib Eye Area are both moderately-highly heritable (heritability of 0.56 and 0.62 respectively), and strongly correlated genetically (correlation = 0.83). The distribution of Carcase Ausmeat Marble Scores suggests that actual marbling extends well past Ausmeat Score 9 – the overall mean is 7.4, and if the trait is normally distributed, there would be approximately 17% of the total sample > score 9, 6% >10, 2% >11 and 1% >12. There is considerable variation in estimated marbling percent within a Carcase Ausmeat Marble Score, and the variation appears to increase as marble score increases. This suggests the Ausmeat Marble Score assessment methodology needs to be extended and its accuracy improved. Genomic relationship matrix G analysis (GBLUP) showed the carcase traits are highly heritable and for most traits the heritability estimates from GBLUP are higher than or similar to those from the pedigree based BLUP. The genetic correlations between the carcase marbling measures (CCMP vs CMAU) and between values for eye muscle area measured by camera images and by the traditional method were unity, as in the BLUP analyses. The Carcase marbling fineness or coarseness indices (CCFI and CCCI) are also highly correlated with marbling measures (CCMP and CMAU). The GEBVs were highly correlated with their BLUP EBVs. This dataset and research establish the concept that genotyping can be a useful tool for the Wagyu breeder and producer – both in use in selection, and for use in sorting animals for production.