Genetic and Phenotypic Characterization of MSA Index and its Association with Carcase and Meat Quality Traits in Angus and Brahman Cattle

MSA Index (MSA_I) predicts overall eating quality of a carcase from predictions of tenderness, juiciness, flavour and overall liking based on extensive consumer taste panel studies. Prices paid by processors for MSA graded meat are consistently higher than non-MSA graded cattle. There is significant industry pressure to determine the level of genetic control for MSA_I. This study used data from Angus (ANGS) and Brahman (BRAH) BIN cattle to estimate genetic parameters for MSA_I and their genetic and phenotypic relationships with key carcase and meat quality traits. Heritabilities for MSA_I were 0.50±0.09 and 0.49±0.16 in ANGS and BRAH cattle, respectively. In ANGS, genetic correlations between MSA_I and carcase weight (CWT), carcase rump fat (CP8), ossification score (OSS), MSA marble score (MSA_M), shear force (SF) and meat colour L (Col_L) were 0.41±0.12, 0.02±0.15, -0.22±0.18, 0.96±0.02, -0.33±0.19 and 0.40±0.16, respectively and in BRAH, were 0.12±0.21, 0.19±0.24, -0.51±0.20, 0.94±0.05, -0.18±0.25 and 0.46±0.21. Similar trends were observed in the correlations between MSA_I and carcase and meat quality traits in both breeds. This study showed that MSA_I has a very high genetic association with MSA_M and, to a lesser extent, OSS in both breeds. Selecting for higher MSA_M and lower OSS will genetically improve MSA_I of carcases of ANGS and BRAH cattle, and the addition of MSA_I as an additional trait in the evaluation would contribute almost no additional information about meat quality or value.