*While the full article for this executive summary is currently under peer review, these initial findings are being made available on BeefResearch.org to enable the industry to act on the research, inform the scientific community of ongoing work, and help prevent duplication of research efforts. Once peer review is complete, a link to the published article will be added to this summary.
Key Takeaways
- USDA beef yield grade equation, developed more than 60 years ago, may not accurately predict results for modern cattle.
- To improve its predictive power, inclusion of cattle type is a feasible alternative.
- The chuck, plate, and round indicate muscularity in the beef carcass.
- Adding more precise specifications about cattle type and anatomical regions to the YG equation may improve estimations of subprimal yield.
BACKGROUND
The United States Department of Agriculture (USDA) dual grading system for beef considers both quality and yield grade to value beef carcasses. Beef grading started in the early 1900s, as a need to provide a consistent indicator of carcass quality and value. As yield variations within the same quality grade were identified, it was necessary to establish an objective and precise system to predict beef yield. Recent research has demonstrated a discrepancy between USDA Yield Grade (YG) and subprimal yield (SY). The current YG equation utilizes only four predictors acquired from a cross-sectional area of the carcass between the 12th and 13th rib. Including additional independent variables may enhance the ability to forecast SY and carcass value. This study aimed to evaluate the accuracy of YG in relation to SY, improve the equation by incorporating additional variables and updated coefficients, and identify the predictive capacity of carcass components in explaining variations in composition.
Methodology
To evaluate the accuracy of the YG equation, individual carcass data (N=744) and cutout data were combined from four different cutability tests. Individual carcass cutout data were obtained through a yield test involving beef sides fabricated to final product fat specifications ranging from 0 to 0.25 inches. Yield data included weights of trimmed subprimals, bone, fat, and lean trimmings. Regression analysis was conducted to assess the current YG equation's predictive ability on SY. Multiple linear regression (MLR) was conducted to evaluate the inclusion of cattle type in the equation, and a new yield grade equation was created which included updated coefficients as well as cattle type adjustments. The change in yield grade proportions was analyzed using the new yield grade formula. Significance was set as (p < 0.05).
Findings
The study's main results reveal a notable linear correlation between YG and subprimal yield, underscoring the need to include cow type into the predictive model. The research conducted in this study revealed that the inclusion of cattle type as a variable significantly improves the predictive capacity of the equation, or how accurately the equation can estimate the yield outcome based upon input variables. The study further revealed certain anatomical parts of the carcass, including the chuck, plate, and round, as reliable indications of muscularity. Additionally, the study examined the effects of using different subprimals as explanatory factors. The findings underscored the need to use subprimal weights as a proportion of the hot carcass weight in order to effectively estimate red meat output. The plate, sirloin, and round sections of the carcass were identified as crucial factors for obtaining precise SY estimations.
Implications
The current USDA yield grade formula has a low predictive ability to forecast SY. The inclusion of cattle type in the equation and updating the coefficients could provide a modified equation that more accurately estimates subprimal yield. The chuck, plate, and round are regions of the carcass that could be used to obtain yield indicators. These changes could provide producers with more accurate grading for their animals, and presents the potential to either an increase or decrease of yield grades depending on cattle type.