Location: Meat Safety and Quality
2023 Annual Report
Objectives
Objective 1: Develop strategies to characterize, manage, measure, predict, and reduce variation in meat quality, composition, and healthfulness traits.
Sub Objective 1A: Utilize metabolomics, proteomics and other biochemical tools to understand and improve the biological variation in meat quality, composition, and healthfulness traits.
Sub Objective 1B: Develop genomic and practical meat management strategies to improve meat quality, composition, and healthfulness.
Objective 2: Develop and validate methods and technologies for measuring and predicting meat quality, composition, and healthfulness traits.
Sub Objective 2A: Improve the accuracy of meat tenderness measurement.
Sub Objective 2B: Develop new and improved technologies for predicting meat quality, healthfulness, and composition traits.
Approach
The inconsistency of product quality and composition has a negative impact on consumer demand for meat. These product characteristics are difficult to measure and can be impacted by genetics and management as well as processing variables. Progress is further impeded by lack of understanding of the biological mechanisms controlling variation in important traits. Producers and processors need better technologies to improve genetic selection and technologies to measure or predict quality and composition characteristics to more accurately determine value and send appropriate signals to other segments of the production chain. Processors also need a better understanding of the interaction between postmortem processing procedures and biochemical changes affecting meat quality traits. This project will develop approaches to improve quality and healthfulness while reducing the variation in meat products. This will be accomplished by providing the information and tools necessary to facilitate equitable valuation of carcasses and meat, improve the quality and consistency of meat, and optimize carcass and meat composition. This project addresses consistency of quality, composition, and healthfulness of red meat products by developing strategies and instrumentation to manage and improve these traits using basic and applied research. Genetic and genomic strategies will be combined with animal and meat management strategies to optimize quality and composition traits. Research will include metabolomics, proteomics and other biochemical tools to characterize variation in quality and composition as well as to evaluate and facilitate implementation of instrumentation for measuring or predicting value determining traits such as carcass grades, tenderness, flavor, lean color stability, and fat quality. Outcomes from this research will provide livestock producers, meat processors and USDA-Agricultural Marketing Service with information and technologies to ensure food animal production systems meet current and future needs for consistent, high quality and healthy meat products for diverse consumers while ensuring economic and environmental sustainability and animal well-being.
Progress Report
Under Objective 1, previous work from our project plan provided evidence that variation in muscle metabolism in the early postmortem period has profound effects on meat quality attributes. We hypothesize that differences in the metabolic machinery interact with the postmortem environment (i.e. temperature decline) to affect the conversion of muscle to meat. To test this hypothesis, we have identified samples from a previous project that had profoundly different outcomes in muscle metabolism. Specifically, these samples differed in ultimate pH ranging from 5.5 to 6.8. We have identified an in vitro system that isolates the metabolic machinery by removing confounding factors such as substrate concentrations. We have modified the system by altering temperature during incubation in a manner that mimics two differing chilling rates. Aliquots of tissue from the samples are being incubated in the system with differing temperature profiles to characterize how differences in metabolic machinery respond to altered chilling conditions. Preliminary results indicate that ranking samples by the rate of postmortem pH decline differs greatly depending on the rate of temperature decline. We have further determined that much of the differential functioning in the system occurs in the first 6 hours of incubation. Results from this experiment will lead to practical approaches to more successfully manage the chilling process to optimize meat quality. Moreover, this work will highlight functional variation in muscle metabolism that can be influenced by genetic selection or antemortem management.
Results from our previous project plan identified post-translational modifications to myoglobin associated with differences in lean color stability. Additional results from our previous project indicate that Angus and Charolais sired steers differed in lean color stability. We hypothesize that post translational modification of myoglobin contributes to breed differences in lean color stability. To test this hypothesis, we identified full blood Angus and Charolais steers in our ongoing germplasm evaluation project (GPE) that were from the same contemporary groups. We collected lean color stability data on steaks from these animals as part of the GPE project. We obtained additional samples from these animals to be subjected to 2-D Electrophoresis and subsequent mass spectrometry to identify differences in post-translational modification of myoglobin. These results will provide further understanding of the source of breed differences in lean color stability.
Previous work in our laboratory indicated that gene expression continued after harvest in pork longissimus muscle and that the differentially expressed genes were associated with pork quality traits. We initiated an experiment to determine the extent to which the postmortem environment influences postmortem gene expression, how long gene expression continues in postmortem muscle, and the optimal sampling time for relating postmortem gene expression to meat quality traits. Pigs were harvested via conventional means. For each carcass, one side was placed in a conventional chilling cooler (1°C). The remaining side was placed in a freezer (-20°C) for 2 hours, after which, the side was returned to the conventional chilling cooler. Muscle samples were removed at 0, 2, 24, 48, 72, and 96 hours postmortem. These muscle samples will be used to quantify gene expression at each time postmortem and to investigate proteomic changes in postmortem muscle. This work will provide the foundation for strategies to better manage carcasses to optimize meat quality traits.
The beef industry is increasingly making use of hot fat trimming to save energy costs, decrease labor requirements, and to facilitate processing of beef fat for renewable energy. Consequentially, there will be selection pressure placed on minimizing kidney-pelvic fat. We are investigating control of kidney-pelvic fat level in beef. Our work shows that there is significant variation among sire groups representing the common U.S. beef breeds. Work is ongoing to conduct a whole-genome analysis of regulation of kidney-pelvic fat deposition.
Under Objective 1, efforts to enhance the genomic prediction of beef eating quality with the University of New England, Australia, have made significant progress. Genomic data collection has been completed and consumer sensory evaluation is near completion. Statistical analyses will proceed once the full dataset has been completed.
Under Objective 2, our laboratory has developed two different technologies to predict beef tenderness using image analysis and visible/near infrared spectroscopy, respectively. Whereas these technologies have been effective in determining carcasses that will produce tender beef cuts, many carcasses not predicted to be tender will produce cuts that are acceptably tender. Thus, these technologies cannot be used to provide pricing signals to improve tenderness of beef. We have also collected tenderness data on thousands of carcasses that have also been assessed by these technologies. We are using machine learning approaches to explore improved methodologies to use these technologies, alone or in concert to predict the tenderness status of beef carcasses more accurately. Data collected as part of the germplasm evaluation (GPE) project and other genomics projects have been combined and stratified by contemporary group. Numerous data reduction and machine learning techniques are being explored to improve prediction of tenderness using these technologies.
Recent research from several academic and industry groups suggests that the current methods for assessing beef carcass leanness, known as USDA yield grades or vision yield grades, have become ineffective. This lack of effectiveness has been observed in beef carcasses, Holstein steer carcasses, and beef on dairy carcasses that result from mating dairy cows to beef bulls. The beef industry has developed a red meat yield task force to develop improved methods of assessing beef carcass leanness. To address this, we are taking advantage of one of the unique populations of cattle at Clay Center, Nebraska. This population of Angus cattle has been maintained with very little selection pressure since 1970. These cattle lack the aggressive selection for growth rate and carcass traits of modern American Angus cattle. In collaboration with Texas Tech University and the beef packing industry, we are testing these cattle and their carcasses with a variety of non-invasive technologies to predict carcass leanness. This will allow us to establish a baseline for predictive accuracy. Then, promising technologies will be evaluated in multiple packing plants and across all biological types of cattle.
Accomplishments
1. Demonstrated increased gene expression in postmortem muscle. Gene expression has generally been thought to cease at the time of harvest and would not be influenced by the postmortem environment. However, many meat quality attributes are profoundly influenced by the postmortem environment. ARS scientists at Clay Center, Nebraska, determined that numerous genes in pork longissimus muscle are more highly expressed at 48 hours postmortem than at the time of harvest. Many of the genes that are highly expressed in the postmortem period code for proteins indicating that the postmortem muscle continues to produce new proteins in an attempt to maintain energy production. Genes that displayed increased expression coincided with previously reported genetic markers that could be used to select for improved quality in pork. This work represents a paradigm shift with regards to gene expression in postmortem muscle and will lead to greater understanding of meat quality development. Moreover, this work will increase the effectiveness of genetic marker discovery for meat quality traits and postmortem management to further improve meat quality.
2. Improvement of ribeye muscle area assessment with the VBG20007L beef grading system and artificial intelligence. The VBG20007L grading camera system uses lasers to quantify errors in beef carcass grading camera application due to carcass processing (ribbing) and instrument operation. In collaboration with industry partners, ARS scientists at Clay Center, Nebraska, determined that significant improvement could be made in ribeye muscle area prediction with inclusion of one of the laser variables from the VBG20007L instrument. Additionally, a ribeye segmentation method was developed using artificial intelligence, which also made a substantial improvement in ribeye area prediction. Implementation of these two improvements by the U.S. beef industry would result in more equitable assessment of beef carcass meat yields improving the accuracy of producer payments and providing better information to producers for genetic and management decisions on their operations.
Review Publications
Sanglard, L.P., Snelling, W.M., Kuehn, L.A., Thallman, R.M., Freetly, H.C., Wheeler, T.L., Shackelford, S.D., King, D.A., Spangler, M.L. 2022. Genetic and phenotypic associations of mitochondrial DNA copy number, SNP, and haplogroups with growth and carcass traits in beef cattle. Journal of Animal Science. 101. Article skac415. https://doi.org/10.1093/jas/skac415.
Price, H.E., Barkley, K.E., Lerner, A.B., Harsh, B.N., Woodworth, J.C., Tokach, M.D., Dritz, S.S., Goodband, R.D., DeRouchey, J.M., O'Quinn, T.G., Allerson, M.W., Fields, B., King, D.A., Wheeler, T.L., Shackelford, S.D., Boler, D.D., Dilger, A.C. 2022. Differences in carcass chilling rate underlie differences in sensory traits of pork chops from pigs with heavier carcass weights. Journal of Animal Science. 100(8). Article skac206. https://doi.org/10.1093/jas/skac206.
Duarte, T.L., Bolkenov, B., Klopatek, S.C., Oltjen, J.W., King, D.A., Shackelford, S.D., Wheeler, T.L., Yang, X. 2022. Evaluating the shelf life and sensory properties of beef steaks from cattle raised on different grass feeding systems in the western United States. Foods. 11(14). Article 2141. https://doi.org/10.3390/foods11142141.
Hernandez, M., Woerner, D.R., Brooks, J., Wheeler, T.L., Legako, J.F. 2023. Influence of aging temperature and duration on descriptive sensory attributes, consumer liking, and the volatile flavor profile of vacuum-packaged beef longissimus. Meat and Muscle Biology. 7(1). Article 15710. http://doi.org/10.22175/mmb.15710.
Hernandez, M., Woerner, D.R., Brooks, J., Wheeler, T.L., Legako, J.F. 2022. Influence of aging temperature and duration on spoilage organism growth, proteolytic activity, and related chemical changes in vacuum-packaged beef longissimus. Meat and Muscle Biology. 6(1). Article 13724. https://doi.org/10.22175/mmb.13724.
