Written by Nancy Crawshaw, Angus Australia Extension Officer — AngusPRO Magazine 2024
Research Breeding Values (RBVs) have emerged as pivotal tools in the TransTasman Angus Cattle Evaluation (TACE), offering Angus breeders invaluable insights into the genetic makeup of their cattle. The recent introduction of two new RBVs, MSA (Meat Standards Australia) Marbling Score and Shear Force, marks a significant stride towards empowering breeders with the ability to make informed selection decisions aimed at enhancing the quality of beef products for the end consumer.
“RBVs are an important step in allowing early release of genetic information for new traits,” says Christian Duff, Angus Australia’s General Manager Genetic Improvement.
Christian says this enables the refinement of both the performance recording information and the analytical models used in their calculation. Importantly, it also allows feedback from users before becoming TACE EBVs.
The MSA Marbling Score RBV and Shear Force RBV draw from a vast dataset comprising over 10,000 animals, predominantly steers from the Angus Sire Benchmarking Program (ASBP), that have undergone both grading at abattoirs and genotyping. Notably, 38 New Zealand-born Angus sires have been included in the ASBP across various cohorts. The MSA Marbling Score RBV and Shear Force RBV are highlighted as significant additions to the existing evaluation framework.
MSA Marbling Score, a subjective assessment of intramuscular fat content and Shear Force, an objective measure of beef tenderness, are both identified as important traits impacting consumer eating experience and carcass value. Both these traits are significant for enhancing Angus carcase value and consumer satisfaction through eating experience.
MSA Marbling Score RBVs are expressed in MSA marbling score units, with higher values indicating the likelihood of progeny producing higher marbling scores in a 400kg steer carcass. Shear Force RBVs, on the other hand, are expressed in kilograms of shear force required to pull a mechanical blade through a piece of cooked meat, with lower values indicating more tender meat.
MSA Marbling Score is used to assess the intramuscular fat content in beef, commonly referred to as marbling. The AusMeat marbling score commonly used in New Zealand, ranges from 0 to 9, with higher scores indicating greater marbling and a higher quality grade. MSA marbling scores are used to provide a finer scale than the AUS-MEAT scores. It is assessed based on the amount as well as distribution of the marbling within the eye muscle. Each MSA marbling score is divided into tenths for grading, creating a score range from 100 to 1,190 in increments of 10.
The Meat Standards Australia (MSA) marble score is a similar grading system used to assess marbling in beef, taking into account the distribution and piece size of the marbling fleck instead of the total amount of marbling such as the AusMeat score. The MSA Marbling Score ranges from 100 to 1200, with higher scores indicating higher marbling levels.
Studies conducted on the Angus Australia data by Angus Genetics Breeding Unit AGBU reveal a substantial genetic component to variations in both MSA Marbling and Shear Force. MSA Marbling has a high heritability of 0.54. This study also looks at the correlation between MSA Marbling with bull ultrasound scan IMF as well as heifer ultrasound scan IMF, both having a genetic correlation with MSA Marbling of 0.35. Shear Force demonstrates a moderate heritability of 0.37, as determined by studies conducted by AGBU.
RBVs for MSA Marbling Score and Shear Force serve as valuable predictors of genetic differences among animals, enabling breeders to select individuals that are predisposed to produce progeny with superior marbling and tenderness characteristics. The routine analysis of these RBVs in the TACE every two weeks ensures breeders have access to up-to-date genetic information to inform their selection strategies.
RBVs enable early access for Angus breeders to select animals with desirable genetics for MSA Marbling Score and Shear Force, while also considering other traits relevant to their breeding objectives. It emphasises the dynamic nature of RBVs, subject to refinements in analytical models and additional performance data collection and analysis.
In conclusion, the integration of MSA Marbling Score and Shear Force RBVs into the TACE framework represents a pivotal advancement in genetic evaluation within the Angus breeding community. By leveraging these RBVs, breeders and commercial farmers can enhance the quality of their cattle and ultimately deliver superior beef products to consumers, thus fostering sustainability and profitability within the industry.