Progress 08/01/17 to 07/04/22
Outputs
PROGRESS REPORT Objectives (from AD-416): Objective 1: Develop strategies to manage and improve variation in meat quality, composition, and healthfulness traits. Sub-objective 1.A: Identification of genetic markers for myoglobin content of pork muscles to increase redness of pork products. Sub-objective 1.B: Estimate effects of three maternal lines and two mating systems on lamb carcass merit. Sub-objective 1.C: Genomic control of dark cutting and other beef quality traits. Sub-objective 1.D: Genomic control of pork fat quality and fatty acid profile. Sub-objective 1.E: Identify and validate novel single-nucleotide polymorphisms (SNP) for beef lean color stability. Sub-objective 1.F: Determine the effect of VQG' pork loin grading camera tenderness class on optimal aging time of boneless pork loins. Sub-objective 1.G: Impact of backgrounding strategies on beef carcass merit. Sub-objective 1.H: To determine the effects of replacing tylosin phosphate (Tylan®) with an essential oil containing limonene in the diet of finishing beef cattle on carcass characteristics. Objective 2: Characterize biological variation in meat quality, composition, and healthfulness traits. Sub-objective 2.A: Determine the impact of sire line on the meat quality defect characterized by a band of very pale, almost white, muscle tissue on the superficial portion of ham muscles (halo). Sub-objective 2.B: Characterize the effect of muscle metabolic efficiency, particularly in mitochondrial efficiency on beef tenderness and lean color stability attributes across varying pH classes in beef carcasses exhibiting normal lean color. Sub-objective 2.C: Determine if there are metabolomic differences between tender and tough beef across postmortem aging times. Sub-objective 2.D: Identification of differentially expressed proteins in beef longissimus steaks classified as tender with stable lean color during simulated retail display compared to steaks classified as tough with labile lean color during simulated retail display. Sub-objective 2.E: Develop technologies for measuring and predicting important traits relating to meat product quality and consistency and the biological mechanisms that control these traits. Approach (from AD-416): The overall goal of this project is to develop approaches to improve quality and healthfulness while reducing the variation in meat products. This will be accomplished by providing the red meat industries with 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 of beef, pork, and lamb. The two objectives of this project address needs in improving 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 approaches. Genetic and genomic strategies will be developed that may be combined with animal and meat management strategies to optimize quality and composition traits. Research will be conducted using 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 grade traits, tenderness, lean color stability, and fat quality. This is the final project plan for 3040-31430-006-000D ⿿Strategies to Optimize Meat Quality and Composition of Red Meat Animals which was replaced with project 3040-31430-007 ⿿Approaches for Improving and Measuring Red Meat Quality and Composition. Under Objective 1. Beef lean color is a primary determinant of consumer purchasing decisions. Cuts produced from the carcasses of some animals do not possess sufficient color life for commercial case-ready programs. Genome analysis of lean color stability on steaks from a large population of cattle representing the 18 most prevalent breeds in the U.S. beef herd identified 417 genes associated with variation in lean color stability. These genes indicate the importance of energy metabolism, which suggest mechanisms requiring further investigation. Follow-up efforts include additional DNA sequencing to identify the specific gene alterations with the greatest effects on color as well as investigating protein and metabolite profiles to further understand the role of these genes in regulating lean color stability. Dark cutting beef results in an annual loss of potential revenue for the U.S. beef industry in excess of $70 million. Dark cutting beef has long been understood to be caused by the animal having a negative energy balance before slaughter, which results in depletion of the animal⿿s muscle energy stores. However, it was not understood why a group of cattle could all be exposed to identical conditions resulting in some carcasses exhibiting the dark-cutting condition and others exhibiting ⿿normal, bright, cherry-red lean color. A naturally-occurring genetic mutation in cattle decreases the susceptibility of cattle to the dark- cutting condition. The mutation discovered in this work helps to account for much of the unexplained variation in susceptibility to dark cutting. The normal sequence is highly-conserved across all mammals and increases susceptibility to the dark-cutting condition. Thus, the mutant, which appears to have originated in British breeds of cattle, confers the desired bright, cherry-red lean. The frequency of the favorable allele ranges from 0 to 0.7 in beef breeds and the frequency of the favorable allele is very low in Holstein steers, which are the primary source of dairy beef. Selection for the favorable allele in this gene should significantly reduce the costly occurrence of dark-cutting beef. The medical community has long been critical of the fatty acid profile of beef products. Thus, there have been countless attempts to modify the fatty acid profile of beef products. However, saturation of fatty acids by rumen microorganisms makes it difficult to modify the fatty acid profile of beef products with changes to cattle diets. Naturally- occurring genetic variation in cattle affect the level of saturated fat in beef. The favorable form of this gene, results in a lower proportion of saturated fat and a higher proportion of monounsaturated fat. It is likely that marketing of products with the favorable gene form will increase beef consumption by consumers concerned about saturated fat intake, while potentially increasing the healthfulness of beef. Sheep production is very labor intensive, and producers need lower cost, lower input production systems to be profitable. Three breed-types of ewes (Katahdin, Polypay, and Composite IV) in two breeding systems: a purebred system, in which each maternal line was mated with rams of the same genetic line, and a terminal mating system in which ewes were mated with Texel rams were evaluated. The increased number of lambs born to Composite IV ewes relative to Polypay and Katahdin, resulted in more pounds of saleable meat produced per ewe exposed, despite the reduction in growth rate and leanness of Composite IV lambs. Use of Texel rams in a terminal mating system improved growth rate and pounds of lean meat of lambs from Composite IV ewes. Thus, Composite IV ewes bred to meat-type rams can be used effectively by producers in a low-input production system with reduced labor costs and improved profitability. Historical trends indicate the size of U.S. hogs is likely to continue to increase. Collaboration with the University of Illinois and Kansas State University determined the effect of increased carcass weights on pork quality. The heaviest group of carcasses weighed 36% more than the industry average and represent the expected average carcass weight by 2050. The increased carcass weight resulted in slower rates of loin muscle chilling. This resulted in loin chops that retained more moisture during cooking and were more tender and juicy. Carcass weight had minimal effect on other pork quality traits including lean color and marbling. These results show that continued improvement in production efficiency through selection for growth in pigs resulting in heavier market weights will improve eating quality of pork chops. Under Objective 2. Beef flavor is the most important factor in determining consumer eating satisfaction of beef products. The role of beef processing strategies and cookery in flavor development has been the subject of extensive research. However, little attention has been paid to the role of inherent animal-to-animal variation in muscle metabolism in the development of beef flavor. Variation in muscle metabolites is associated with both positive and negative flavor attributes in beef strip loin steaks. These findings provide greater understanding of the mechanisms responsible for variation in beef flavor as well as selection strategies to improve overall beef flavor and consistency, which will increase consumer satisfaction and repeat purchases for beef. These results may add millions of dollars in revenue to the U.S. beef industry through increased demand for high quality beef products. The newest (7L) version of the VBG2000 grading camera was developed to more clearly quantify errors in operation of the grading camera during online application. Beef packing companies are anxious to adopt the 7L camera to improve the ability of plant employees in both camera operation and the proper presentation of the beef carcass for grading camera operation. At the request of USDA-Agricultural Marketing Service (AMS), the new 7L camera was compared to the currently approved VBG2000-LED grading camera and demonstrated to provide equivalent results with enhanced capacity to identify operational errors. The 7L camera has since been approved by AMS, and will improve employee training, will result in more accurate grade data, and is being adopted by all large North American beef packing plants for evaluation of marbling score and yield grade traits for USDA grading and certification activities. Human sensory evaluation for meat quality traits, such as tenderness, is the gold standard but is time consuming and expensive to conduct. Alternatively, shear force tests of cooked meat can be used to provide an accurate measure of meat tenderness. Historically, shear force tests were conducted parallel to the meat fiber direction, but for some meat cuts this is technically very challenging. To overcome this limitation, a method was developed and evaluated to conduct shear force perpendicular to the cut surface of the steak rather than parallel to the meat fiber direction. Shearing perpendicular to the cut surface of the steak provided similar mean shear force values and improved repeatability of the measurement. This new research tool will improve the accuracy of meat tenderness measurement and will provide an additional tool for the meat industries to evaluate and market meat products at higher value and with improved overall consumer eating satisfaction. Cured ham color is of great importance in meeting consumer expectations for ham products. Recently the pork industry identified a color defect in ham muscles that caused a high level of consumer dissatisfaction with cured ham products. Collaboration with pork processors determined the color defect occurs in almost all pigs regardless of production system or management practices. Sire lines differed significantly in traits that affect muscle color, thus, genetic selection could be utilized to minimize or eliminate the occurrence of the ham color defect and increase consumer satisfaction and the value of ham products. Tenderness is a primary driver of customer satisfaction of beef products. However, despite substantial research efforts, a large portion of the variation in tenderness cannot be explained by known factors influencing tenderness. In collaboration with scientists from Colorado State University, we characterized all compounds found in beef related to tenderness and identified more than 2,500 compounds that were associated with differences in tenderness. Of these, 28 were known compounds and the three most related to tenderness differences could be used to predict loin steak tenderness and facilitate marketing of a guaranteed tender brand of beef, which will improve consumer demand for beef products. The recent development of tenderness claims certification standards has given the beef industry added impetus to implement a tenderness-based marketing system. To effectively execute a tenderness-based marketing strategy, retailers need to be able to market all loin and rib cuts from a qualifying carcass as certified tender. Yet, at present, the certification protocols do not favor inclusion of top sirloins, which represent a substantial retail meat cut feature. Tenderness classes based on the VBG2000 beef grading camera allowed for identification of carcasses with more favorable top sirloin tenderness. This work showed that tenderness testing with the beef grading camera in combination with refrigerated aging for 28 days can be used to produce consistently tender top sirloin steaks that qualify for a guaranteed tender marketing claim. ACCOMPLISHMENTS 01 Validated biomarkers for beef quality. A majority of the variation in lean color, tenderness, and flavor cannot be explained. Recently, novel biomarkers associated with intermediates of muscle metabolism and cellular stress response have been identified that explain much more of the variation in meat quality traits than previously possible. However, these needed to be validated in more comprehensive studies. USDA-ARS scientists at Clay Center, Nebraska verified that these candidate biomarkers are predictive of variation in beef tenderness, flavor, and color and explain variation in these traits not previously accounted for. Implementation of these findings provide greater understanding of the mechanisms responsible for variation in meat quality and lead to selection strategies to improve quality, increase consumer satisfaction, and repeat purchases of beef. These outcomes will add millions of dollars in revenue to the U.S. beef industry through increased demand for high quality beef products. 02 Determined mechanisms for high pH, dark colored beef. High pH beef is heavily discounted because they have dark color and are undesirable to consumers. Although occurrence is seasonal, on average 3% of beef is dark enough to be discounted. Previous research determined that muscles with high pH had increased mitochondrial content and less efficient mitochondrial function than normal pH muscles. USDA-ARS scientists at Clay Center, Nebraska determined mitochondrial abundance and function across the range of meat pH observed in the industry to provide insight into the role of mitochondrial function in determining muscle pH. These results provide clarity in some of these relationships among metabolic function and meat quality traits, such as more completely explaining animal-to-animal variation in meat tenderness, flavor, and lean color. These results will lead to strategies to improve quality, increase consumer satisfaction, and repeat purchases of beef by decreasing the occurence of undesirable high pH beef. These outcomes will add millions of dollars in revenue to the U.S. beef industry through increased consumer satisfaction and demand for high quality beef products. 03 Confirming accuracy of beef grades. In the U.S., beef quality grading is based on the visible flecks of fat in the rib/loin muscle (marbling score) determined by an instrument grading camera. Consumers and meat marketers sometimes complain about some steaks appearing to have less marbling than they expect for a specific quality grade program. There is significant biological variation in marbling score among carcass sides and among steaks within the ribeye and loin that has never been quantified. USDA-ARS scientists at Clay Center, Nebraska, determined the level of variation in beef grading camera marbling score and ribeye fat among ribeye and loin steaks from both sides of beef carcasses. There are significant differences among ribeye and loin steaks in both instrument marbling score and fat content. These data explain observed discrepancies in steak marbling level and quality grade category and provide scientific data to alleviate concerns of inaccurate grading or deceptive marketing.
Impacts
(N/A)
Publications
- Warner, R.D., Wheeler, T.L., Ha, M., Li, X., Bekhit, A., Morton, J., Vaskoska, R., Dunshea, F.R., Liu, R., Purslow, P., Zhang, W. 2021. Meat tenderness: Advances in biology, biochemistry, molecular mechanisms and new technologies. Meat Science. 185. Article 108657. https://doi.org/10. 1016/j.meatsci.2021.108657.
- Nonneman, D.J., Keel-Mercer, B.N., Lindholm-Perry, A.K., Rohrer, G.A., Wheeler, T.L., Shackelford, S.D., King, D.A. 2022. Transcriptomic analysis for pork color ⿿ The ham halo effect in biceps femoris. Meat and Muscle Biology. 6(1):1-8. Article 13050. https://doi.org/10.22175/mmb.13050.
- Artegoitia, V.M., Newman, J.W., Foote, A.P., Shackelford, S.D., King, D.A., Wheeler, T.L., Lewis, R.M., Freetly, H.C. 2022. Non-invasive metabolomics biomarkers of production efficiency and beef carcass quality traits. Scientific Reports. 12. Article 231. https://doi.org/10.1038/s41598-021- 04049-2.
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Progress 10/01/20 to 09/30/21
Outputs
PROGRESS REPORT Objectives (from AD-416): Objective 1: Develop strategies to manage and improve variation in meat quality, composition, and healthfulness traits. Sub-objective 1.A: Identification of genetic markers for myoglobin content of pork muscles to increase redness of pork products. Sub-objective 1.B: Estimate effects of three maternal lines and two mating systems on lamb carcass merit. Sub-objective 1.C: Genomic control of dark cutting and other beef quality traits. Sub-objective 1.D: Genomic control of pork fat quality and fatty acid profile. Sub-objective 1.E: Identify and validate novel single-nucleotide polymorphisms (SNP) for beef lean color stability. Sub-objective 1.F: Determine the effect of VQG' pork loin grading camera tenderness class on optimal aging time of boneless pork loins. Sub-objective 1.G: Impact of backgrounding strategies on beef carcass merit. Sub-objective 1.H: To determine the effects of replacing tylosin phosphate (Tylan®) with an essential oil containing limonene in the diet of finishing beef cattle on carcass characteristics. Objective 2: Characterize biological variation in meat quality, composition, and healthfulness traits. Sub-objective 2.A: Determine the impact of sire line on the meat quality defect characterized by a band of very pale, almost white, muscle tissue on the superficial portion of ham muscles (halo). Sub-objective 2.B: Characterize the effect of muscle metabolic efficiency, particularly in mitochondrial efficiency on beef tenderness and lean color stability attributes across varying pH classes in beef carcasses exhibiting normal lean color. Sub-objective 2.C: Determine if there are metabolomic differences between tender and tough beef across postmortem aging times. Sub-objective 2.D: Identification of differentially expressed proteins in beef longissimus steaks classified as tender with stable lean color during simulated retail display compared to steaks classified as tough with labile lean color during simulated retail display. Sub-objective 2.E: Develop technologies for measuring and predicting important traits relating to meat product quality and consistency and the biological mechanisms that control these traits. Approach (from AD-416): The overall goal of this project is to develop approaches to improve quality and healthfulness while reducing the variation in meat products. This will be accomplished by providing the red meat industries with 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 of beef, pork, and lamb. The two objectives of this project address needs in improving 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 approaches. Genetic and genomic strategies will be developed that may be combined with animal and meat management strategies to optimize quality and composition traits. Research will be conducted using 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 grade traits, tenderness, lean color stability, and fat quality. Under Objective 2. Lean color is the primary factor considered by consumers when making beef purchasing decisions, and products not meeting consumer expectations are discriminated against. Muscle pH is a driver of muscle color and muscles with high muscle pH are termed ⿿dark cutters and are heavily discounted. Previous research from our laboratory determined that increased severity of the dark cutter condition resulted in less red, less stable lean color along with increased incidence of undesirable flavor attributes. Moreover, that work indicated that beef from mild dark cutters had increased toughness relative to severe dark cutter and normal pH beef. We determined that muscles with the dark cutting condition had increased mitochondrial content and less efficient mitochondrial function than normal pH muscles. However, the impact of mitochondrial function on color, tenderness, and flavor traits of muscles across the full range of pH values is not known. We have initiated an experiment to determine the effects of muscle pH classes on beef flavor, tenderness, and color stability. Carcasses were selected based on loin muscle pH (less than 5.55, 5.56 to 5.7, 5.71 to 5.9, and greater than 5.9) . Steaks from each carcass were used for simulated retail display to determine color stability, objective measures of tenderness, and evaluation by a trained sensory panel for beef flavor attributes. Moreover, component traits describing mechanisms that contribute to these traits, as well as intermediates of muscle metabolism, mitochondrial abundance, and mitochondrial function are being measured. These data are currently being collected and analyzed. These data will be contrasted across pH categories to determine how muscle pH affects important meat quality traits and how metabolism impacts muscle pH. These results will be independent validation of previous metabolic fingerprinting experiments. Under Objective 2. In the United States beef carcass quality grading is primarily a function of marbling score. Consumers and meat marketers sometimes complain about some steaks appearing to have less marbling than they expect for the quality grade program they purchased. The United States Standards for Grades of Carcass Beef state that ⿿when both sides of a carcass have been ribbed prior to presentation for grading and the characteristics of the two ribeyes (area, marbling, color, texture, and firmness) would justify different quality and/or yield grades, the final grade of the carcass shall reflect the ⿿highest of each of these grades as determined from either side. Marbling score can frequently differ among carcass sides. Additionally, visible marbling and intramuscular fat content can differ among the various ribeye and strip loin steaks from a carcass. USDA-ARS scientists at Clay Center, Nebraska, assessed the level of variation in beef grading camera marbling score and intramuscular fat among various ribeye and strip loin steak locations from both sides of beef carcasses. Preliminary data indicate some ribeye steaks had lower marbling scores than strip loin steaks from the same carcasses, despite no difference in ether-extractable intramuscular fat level between steaks. Also, marbling scores of ribeye steaks were lower on average than the marbling score of the corresponding carcass, with more than twice as many ribeye steaks having marbling scores below modest as was expected based on the marbling scores of the carcass sides. These data highlight the normal biological variation that occurs within muscles and across carcass sides and explains observations made at the retail level and should help alleviate concerns of deceptive marketing. Record of Any Impact of Maximized Teleworking Requirement: The covid-19 pandemic has caused a delay in many research activities from collecting data and samples to processing samples in the lab for various assays. Inability to fly has prevented sample collection from some commercial facilities. Day-to-day scientist interactions, spontaneous research discussions, and stakeholder interactions are all severely reduced and continue to impact scientific productivity. ACCOMPLISHMENTS 01 Determined influence of muscle metabolism intermediates on beef flavor development. Beef flavor is the most important factor in determining consumer eating satisfaction of beef products. The role of beef processing strategies and cookery in flavor development has been the subject of extensive research. However, little attention has been paid to the role of inherent animal-to-animal variation in muscle metabolism in the development of beef flavor. USDA-ARS scientists at Clay Center, Nebraska, determined that variation in muscle metabolites is associated with both positive and negative flavor attributes in beef strip loin steaks. These findings provide greater understanding of the mechanisms responsible for variation in beef flavor as well as selection strategies to improve overall beef flavor and consistency, which will increase consumer satisfaction and repeat purchases for beef. These results may potentially add millions of dollars in revenue to the U.S. beef industry through increased demand for high quality beef products. 02 Improved beef grading camera. The newest (7L) version of the VBG2000 grading camera was developed to more clearly quantify errors in operation of the grading camera during online application. Beef packing companies are anxious to adopt the 7L camera to improve the ability of plant employees in both camera operation and the proper presentation of the beef carcass for grading camera operation. At the request of USDA- Agricultural Marketing Service, USDA-ARS scientists at Clay Center, Nebraska, compared the new 7L camera to the currently approved VBG2000- LED grading camera and demonstrated it provided equivalent results with enhanced capacity to identify operational errors. The 7L camera has since been approved by AMS, and will improve employee training, will result in more accurate grade data, and is being adopted by all large North American beef packing plants for evaluation of marbling score and yield grade traits for USDA grading and certification activities. 03 Novel meat tenderness measurement. Human sensory evaluation for meat quality traits, such as tenderness, is the gold standard but is time consuming and expensive to conduct. Alternatively, shear force tests of cooked meat can be used to provide an accurate measure of meat tenderness. Historically, shear force tests were conducted parallel to the meat fiber direction, but for some meat cuts this is technically very challenging. To overcome this limitation, USDA-ARS scientists at Clay Center, Nebraska, developed and evaluated methods to conduct shear force perpendicular to the cut surface of the steak rather than parallel to the meat fiber direction and demonstrated that shearing perpendicular to the cut surface of the steak provided similar mean shear force values and improved repeatability of the measurement. This new research tool will improve the accuracy of meat tenderness measurement, providing an additional tool for the meat industries to evaluate and market meat products at higher value and with improved overall consumer eating satisfaction.
Impacts
(N/A)
Publications
- King, D.A., Shackelford, S.D., Wheeler, T.L. 2021. Postmortem aging time and marbling class effects on flavor of three muscles from beef top loin and top sirloin subprimals. Meat and Muscle Biology. 5(1). https://doi.org/ 10.22175/mmb.10939.
- King, D.A., Shackelford, S.D., Cushman, R.A., Wheeler, T.L. 2021. Extended aging and marbling class effects on color stability of beef Longissimus lumborum, Gluteus medius, and Biceps femoris steaks. Meat and Muscle Biology. 5(1):1-14. https://doi.org/10.22175/mmb.11139.
- Lerner, A.B., Rice, E.A., Tokach, M.D., DeRouchey, J.M., Dritz, S.S., Goodband, R.D., Woodworth, J.C., O'Quinn, T.G., Gonzalez, J.M., Allerson, M.W., Dilger, A.C., Boler, D.D., Price, H.E., Lowell, J.E., Richardson, E., Barkley, K.E., Honegger, L.T., Harsh, B.N., Shackelford, S.D., Wheeler, T. L., King, D.A., Fields, B. 2020. Effects of space allowance and marketing strategy on growth performance of pigs raised to 165 kg. Translational Animal Science. 4:1252-1262. https://doi.org/10.1093/tas/txaa065.
- King, D.A., Shackelford, S.D., Nonneman, D.J., Rohrer, G.A., Wheeler, T.L. 2020. Sire variation in the severity of the ham halo condition. Meat and Muscle Biology. 4(1). https://doi.org/10.22175/mmb.9743.
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Progress 10/01/19 to 09/30/20
Outputs
Progress Report Objectives (from AD-416): Objective 1: Develop strategies to manage and improve variation in meat quality, composition, and healthfulness traits. Sub-objective 1.A: Identification of genetic markers for myoglobin content of pork muscles to increase redness of pork products. Sub-objective 1.B: Estimate effects of three maternal lines and two mating systems on lamb carcass merit. Sub-objective 1.C: Genomic control of dark cutting and other beef quality traits. Sub-objective 1.D: Genomic control of pork fat quality and fatty acid profile. Sub-objective 1.E: Identify and validate novel single-nucleotide polymorphisms (SNP) for beef lean color stability. Sub-objective 1.F: Determine the effect of VQG' pork loin grading camera tenderness class on optimal aging time of boneless pork loins. Sub-objective 1.G: Impact of backgrounding strategies on beef carcass merit. Sub-objective 1.H: To determine the effects of replacing tylosin phosphate (Tylan®) with an essential oil containing limonene in the diet of finishing beef cattle on carcass characteristics. Objective 2: Characterize biological variation in meat quality, composition, and healthfulness traits. Sub-objective 2.A: Determine the impact of sire line on the meat quality defect characterized by a band of very pale, almost white, muscle tissue on the superficial portion of ham muscles (halo). Sub-objective 2.B: Characterize the effect of muscle metabolic efficiency, particularly in mitochondrial efficiency on beef tenderness and lean color stability attributes across varying pH classes in beef carcasses exhibiting normal lean color. Sub-objective 2.C: Determine if there are metabolomic differences between tender and tough beef across postmortem aging times. Sub-objective 2.D: Identification of differentially expressed proteins in beef longissimus steaks classified as tender with stable lean color during simulated retail display compared to steaks classified as tough with labile lean color during simulated retail display. Sub-objective 2.E: Develop technologies for measuring and predicting important traits relating to meat product quality and consistency and the biological mechanisms that control these traits. Approach (from AD-416): The overall goal of this project is to develop approaches to improve quality and healthfulness while reducing the variation in meat products. This will be accomplished by providing the red meat industries with 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 of beef, pork, and lamb. The two objectives of this project address needs in improving 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 approaches. Genetic and genomic strategies will be developed that may be combined with animal and meat management strategies to optimize quality and composition traits. Research will be conducted using 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 grade traits, tenderness, lean color stability, and fat quality. Under Objective 1. Interaction of beef dark cutting genotype and implant strategy on lean color. Current data indicate that both genomic variation and implant strategy impact lean color and the percentage of carcasses with dark lean color. Work is ongoing to assess the interaction of these factors. Preliminary analyses suggest that the impact of implant strategies is greatest for cattle that are genetically predisposed to produce dark colored lean. Under Objective 2. Lean color is the primary factor considered by consumers when making beef purchasing decisions, and products that lose their bright red color during retail display are often discarded. Thus, insufficient color-life is a large source of food waste. Tenderness is the primary driver determining beef customer satisfaction. These two economically important meat quality traits are generally considered separately in experiments. However, recent results indicate that variation in energy producing systems exists that beneficially affect both traits. Moreover, previous research indicates that beef flavor is impacted by similar variation in energy production. We have initiated an experiment to determine the influence of the ⿿fingerprint of small molecules within beef samples (metabolic profile) on these three traits. Beef carcasses have been selected to represent predicted tenderness and color stability classes (i.e. tender-stable, tender-labile, tough-stable, and tough-labile). Strip loins were obtained from each carcass and stored for either 12 or 26 days in refrigeration. Aged steaks were cut from each strip loin and used to quantify lean color stability, tenderness, or trained sensory panel flavor ratings. Moreover, component traits describing mechanisms regulating variation in these traits as well as metabolic biomarkers previously identified to be predictive of these traits are being measured. Analysis of these data is in progress. These results will be independent validation of previous metabolic fingerprinting experiments. Also, these results, will allow selection of samples to represent the most extreme combinations of tenderness, flavor, and color stability for metabolic profiling. The metabolic profiles of these groups will be contrasted to identify metabolites contributing to these important meat quality traits. Under Objective 2. Objective measurement of meat tenderness. Slice shear force is a rapid method of tenderness measurement that allows for greater throughput than the traditional Warner-Bratzler shear force method. For some muscles, slice shear force procedures have required knowledge of whether the muscle originated from the left or right side of the carcass. To overcome this problem, methods were developed for sampling perpendicular to the cut surface of the steak rather than parallel to the muscle fiber orientation. A concern was that when a similar approach was attempted with Warner-Bratzler shear force, sampling perpendicular to the cut surface of the steak resulted in a substantial reduction in the mean shear force value and the repeatability of shear force. Preliminary data indicate that for slice shear force, sampling perpendicular to the cut surface of the steak allowed sampling up to 6 slices per steak with improved repeatability and little effect on mean slice shear force values. Accomplishments 01 Classification of beef carcasses for top sirloin tenderness. The recent development of tenderness claims certification standards has given the beef industry added impetus to implement a tenderness-based marketing system. For retailers to effectively execute a tenderness-based marketing strategy, retailers need to be able to market all loin and rib cuts from a qualifying carcass as certified tender. Yet, at present, the certification protocols do not favor inclusion of top sirloins, which represent a substantial retail meat cut feature. USDA-ARS scientists in Clay Center, Nebraska, determined that tenderness classes based on the VBG2000 beef grading camera allowed for identification of carcasses with more favorable top sirloin tenderness. This work showed that tenderness testing with the beef grading camera in combination with refrigerated aging for 28 days can be used to produce consistently tender top sirloin steaks that qualify for a guaranteed tender marketing claim. This potentially could lead to over $18,000,000 of added annual revenue for the U.S. beef industry. 02 Improving meat tenderness and lean color simultaneously. Premature color change resulting in loss of bright red color of beef products during retail display results in those products being discarded, causing significant food waste. Beef tenderness is the primary driver of consumer satisfaction in beef products. Thus, both traits have been extensively studied but are generally thought to be unrelated by scientists. However, USDA-ARS scientists at Clay Center, Nebraska, identified some commonalities in the molecular fingerprints associated with favorable outcomes for both traits. Currently, 10% of retail beef products are discounted and 5% are discarded, costing the industry greater than $1 billion, annually. Meanwhile insufficient tenderness reduces repeat purchases. These findings should lead to strategies to improve both tenderness and color stability to mitigate food waste and improve consumer satisfaction with beef adding millions of dollars in revenue to the U.S. beef industry. 03 New measure of meat tenderness. Tenderness is a primary driver of customer satisfaction of beef products. However, despite substantial research efforts, a large portion of the variation in tenderness cannot be explained by known factors influencing tenderness. USDA-ARS scientists in Clay Center, Nebraska, validated a new approach to measuring protein degradation that is a primary determinant of meat tenderness. This methodology provides scientists with an improved tool to identify animals that produce more tender meat and better understand the biology controlling meat tenderness. A better understanding of variation in meat tenderness could lead to the ability to guarantee meat tenderness which will improve consumer satisfaction and demand for beef products and add millions of dollars in revenue to the U.S. beef industry.
Impacts
(N/A)
Publications
- Rice, E.A., Lerner, A.B., Olson, B.A., Prill, L.L., Drey, L.N., Price, H.E. , Lowell, J.E., Harsh, B.N., Barkley, K.E., Honegger, L.T., Richardson, E., Woodworth, J.C., Gonzalez, J.M., Tokach, M.D., DeRouchey, J.M., Dritz, S. S., Goodband, R.D., Allerson, M.W., Fields, B., Shackelford, S.D., King, D. A., Wheeler, T.L., Dilger, A.C., Boler, D.D., O'Quinn, T.D. 2019. Effects of increased pork hot carcass weights. 1: Chop thickness impact on consumer visual ratings. Meat and Muscle Biology. 3(1):433-446.
- Overholt, M.F., Arkfeld, E.K., Bryan, E.E., King, D.A., Wheeler, T.L., Dilger, A.C., Shackelford, S.D., Boler, D.D. 2019. Effect of hot carcass weight on the rate of temperature decline of pork hams and loins in a blast-chilled commercial abattoir. Journal of Animal Science. 97(6):2441- 2449.
- Price, H.E., Lerner, A.B., Rice, E.A., Lowell, J.E., Harsh, B.N., Barkley, K.E., Honegger, L.T., Richardson, E., 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., Dilger, A.C., Boler, D.D. 2019. Characterizing ham and loin quality as hot carcass weight increases to an average of 119 kilograms. Meat and Muscle Biology. 3(1):330-343.
- Gredell, D.A., Schroeder, A.R., Belk, K.E., Broeckling, C.D., Heuberger, A. L., Kim, S., King, D.A., Shackelford, S.D., Sharp, J.L., Wheeler, T.L., Woerner, D.R., Prenni, J.E. 2019. Comparison of machine learning algorithms for predictive modeling of beef attributes using rapid evaporative ionization mass spectrometry (REIMS) data. Scientific Reports. 9:5721.
- Rice, E.A., Lerner, A.B., Olson, B.A., Prill, L.L., Drey, L.N., Price, H.E. , Lowell, J.E., Harsh, B.N., Barkley, K.E., Honegger, L.T., Richardson, E., Woodworth, J.C., Gonzalez, J.M., Tokach, M.,D. DeRouchey, J.M., Dritz, S. S., Goodband, R.D., Allerson, M.W., Fields, B., Shackelford, S.D., King, D. A., Wheeler, T.L., Dilger, A.C., Boler, D.B., O'Quinn, T.G. 2019. Effects of increased pork hot carcass weights. II: Loin quality characteristics and palatability ratings. Meat and Muscle Biology. 3(1):447-456.
- Schulte, M.D., Johnson, L.G., Zuber, E.A., Steadham, E.M., King, D.A., Huff-Lonergan, E., Lonergan, S.M. 2020. Investigation of the sarcoplasmic proteome contribution to the development of pork loin tenderness. Meat and Muscle Biology. 4(1):8, 1-14.
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Progress 10/01/18 to 09/30/19
Outputs
Progress Report Objectives (from AD-416): Objective 1: Develop strategies to manage and improve variation in meat quality, composition, and healthfulness traits. Sub-objective 1.A: Identification of genetic markers for myoglobin content of pork muscles to increase redness of pork products. Sub-objective 1.B: Estimate effects of three maternal lines and two mating systems on lamb carcass merit. Sub-objective 1.C: Genomic control of dark cutting and other beef quality traits. Sub-objective 1.D: Genomic control of pork fat quality and fatty acid profile. Sub-objective 1.E: Identify and validate novel single-nucleotide polymorphisms (SNP) for beef lean color stability. Sub-objective 1.F: Determine the effect of VQG' pork loin grading camera tenderness class on optimal aging time of boneless pork loins. Sub-objective 1.G: Impact of backgrounding strategies on beef carcass merit. Sub-objective 1.H: To determine the effects of replacing tylosin phosphate (Tylan®) with an essential oil containing limonene in the diet of finishing beef cattle on carcass characteristics. Objective 2: Characterize biological variation in meat quality, composition, and healthfulness traits. Sub-objective 2.A: Determine the impact of sire line on the meat quality defect characterized by a band of very pale, almost white, muscle tissue on the superficial portion of ham muscles (halo). Sub-objective 2.B: Characterize the effect of muscle metabolic efficiency, particularly in mitochondrial efficiency on beef tenderness and lean color stability attributes across varying pH classes in beef carcasses exhibiting normal lean color. Sub-objective 2.C: Determine if there are metabolomic differences between tender and tough beef across postmortem aging times. Sub-objective 2.D: Identification of differentially expressed proteins in beef longissimus steaks classified as tender with stable lean color during simulated retail display compared to steaks classified as tough with labile lean color during simulated retail display. Sub-objective 2.E: Develop technologies for measuring and predicting important traits relating to meat product quality and consistency and the biological mechanisms that control these traits. Approach (from AD-416): The overall goal of this project is to develop approaches to improve quality and healthfulness while reducing the variation in meat products. This will be accomplished by providing the red meat industries with 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 of beef, pork, and lamb. The two objectives of this project address needs in improving 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 approaches. Genetic and genomic strategies will be developed that may be combined with animal and meat management strategies to optimize quality and composition traits. Research will be conducted using 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 grade traits, tenderness, lean color stability, and fat quality. Under Objective 2. Lean color is the primary factor considered by consumers when making beef purchasing decisions, and products with short color life are often discarded. Thus, insufficient color-life is a large source of food waste. Tenderness is the primary driver determining beef customer satisfaction. These two economically important meat quality traits are generally considered separately in experiments. However, recent results indicate that metabolic factors exist that beneficially affect both traits. Moreover, previous research indicates that beef flavor is impacted by muscle metabolism. We have initiated an experiment to determine the influence of metabolic profiles on these three traits. Beef carcasses have been selected to represent predicted tenderness and color stability classes (i.e. tender-stable, tender-labile, tough-stable, and tough-labile). Strip loins were obtained from each carcass and stored for either 12 or 26 days in refrigeration. After aging, steaks were cut from each strip loin and used to quantify lean color stability, tenderness, or trained sensory panel flavor ratings. Analysis of these data is in progress. From these results, groups of samples will be selected to represent the most extreme combinations of tenderness and color stability (i.e. tender-stable, tough-labile, etc.) for metabolic profiling. Moreover, samples with the greatest differences in flavor attributes will be selected for metabolic profiling. The metabolic profiles of these groups will be contrasted to identify metabolites contributing to these important meat quality traits. Under Objective 2. A simplified protocol for instrumental measurement of beef top sirloin tenderness with slice shear force was developed. This procedure will make it easier for research institutions and industry laboratories to measure slice shear force of top sirloin. It was determined that the simplified procedure allows for more thorough sampling of each steak, which increases the repeatability of the measurement. Moreover, it was determined that the simplified procedure did not change the mean slice shear force value compared to the conventional procedure. Therefore, transition to the new procedure should be seamless. Additional data collection is needed to confirm preliminary results. Accomplishments 01 Identified a genetic selection approach to solve a pork color defect. Cured ham color is of great importance in meeting consumer expectations for ham products. Recently the pork industry identified a color defect in ham muscles that caused a high level of consumer dissatisfaction with cured ham products. USDA-ARS scientists at Clay Center, Nebraska, collaborated with pork processors to determine the color defect occurs in the almost all pigs regardless of production system or management practices. They also determined that sire lines differed significantly in traits that affect muscle color, thus, genetic selection could be utilized to minimize or eliminate the occurrence of the ham color defect and increase consumer satisfaction and the value of ham products. 02 New predictors of beef tenderness discovered. Tenderness is a primary driver of customer satisfaction of beef products. However, despite substantial research efforts, a large portion of the variation in tenderness cannot be explained by known factors influencing tenderness. USDA-ARS scientists in Clay Center, Nebraska, in collaboration with scientists from Colorado State University, conducted the first characterization of all compounds found in beef related to tenderness and identified more than 2,500 compounds that were associated with differences in tenderness. Of these, 28 were known compounds and the three most related to tenderness differences could be used to predict loin steak tenderness and facilitate marketing of a guaranteed tender brand of beef, which will improve consumer demand for beef products. 03 Identified genomic variation in beef cattle that reduces saturated fat in beef. The medical community has long been critical of the fatty acid profile of beef products. Thus, there have been countless attempts to modify the fatty acid profile of beef products. But, saturation of fatty acids by rumen microorganisms makes it difficult to modify the fatty acid profile of beef products with changes to cattle diets. Therefore, this study was conducted to determine the sources and level of genomic control of fatty acid profile in beef breeds commonly used in the U.S. USDA-ARS scientists at Clay Center, Nebraska, discovered naturally-occurring genetic variation in cattle affecting the level of saturated fat in beef. The favorable form of this gene, results in a lower proportion of saturated fat and a higher proportion of monounsaturated fat. It is likely that marketing of products with favorable gene form will increase beef consumption by consumers concerned about saturated fat intake, while potentially increasing the healthfulness of beef. 04 Identified a breed-type of ewes that excel in production efficiency. Sheep production is very labor intensive and producers need lower cost, lower input production systems in order to be profitable. USDA-ARS scientists at Clay Center, Nebraska, compared three breed-types of ewes (Katahdin, Polypay, and Easycare) in two breeding systems: a purebred system to produce breeding ewes and a terminal mating system in which ewes were mated with Texel rams to produce lambs for meat. The increased number of lambs born to Easycare ewes relative to Polypay and Katahdin, resulted in more pounds of saleable meat produced per ewe exposed, despite the reduction in growth rate and leanness of Easycare lambs. Use of Texel rams in a terminal mating system improved growth rate and pounds of lean meat of lambs from Easycare ewes. Thus, Easycare ewes bred to meat-type rams can be used effectively by producers in a low-input production system with reduced labor costs and improved profitablility. 05 Increases in pork carcass weight will improve tenderness of pork loin chops. Historical trends indicate the size of U.S. hogs is likely to continue to increase, thus, USDA-ARS scientists at Clay Center, Nebraska, collaborated with the University of Illinois and Kansas State University to determine the effect of increased carcass weights on pork quality. Results indicated the heaviest group of carcasses weighed 36% more than the industry average and represent the expected average carcass weight by 2050. The increased carcass weight resulted in slower rates of loin muscle chilling. This, in turn, resulted in loin chops that retained more moisture during cooking and were more tender and juicier. Carcass weight had minimal effect on other pork quality traits including lean color and marbling. These results show that continued improvement in production efficiency through selection for growth in pigs resulting in heavier market weights will improve eating quality of pork chops.
Impacts
(N/A)
Publications
- King, D.A., Shackelford, S.D., Broeckling, C.D., Prenni, J.E., Belk, K.E., Wheeler, T.L. 2019. Metabolomic investigation of tenderness and aging response in beef longissimus steaks. Meat and Muscle Biology. 3(1):76-89.
- Bennett, G.L., Tait, R.G., Shackelford, S.D., Wheeler, T.L., King, D.A., Casas, E., Smith, T.P.L. 2019. Enhanced estimates of carcass and meat quality effects for polymorphisms in myostatin and mu-calpain genes. Journal of Animal Science. 97(2):569-577.
- Santos, C., Zhao, J., Dong, X., Lonergan, S., Huff-Lonergan, E., Outhouse, A., Carlson, K., Prusa, K., Fedler, C., Yu, C., Shackelford, S.D., King, D. A., Wheeler, T.L. 2018. Predicting aged pork quality using a portable Raman device. Meat Science. 145:79-85.
- Freking, B.A., King, D.A., Shackelford, S.D., Wheeler, T.L., Smith, T.P.L. 2018. Effects and interactions of myostatin and callipyge mutations: I. Growth and carcass traits. Journal of Animal Science. 96:454⿿461.
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Progress 10/01/17 to 09/30/18
Outputs
Progress Report Objectives (from AD-416): Objective 1: Develop strategies to manage and improve variation in meat quality, composition, and healthfulness traits. Sub-objective 1.A: Identification of genetic markers for myoglobin content of pork muscles to increase redness of pork products. Sub-objective 1.B: Estimate effects of three maternal lines and two mating systems on lamb carcass merit. Sub-objective 1.C: Genomic control of dark cutting and other beef quality traits. Sub-objective 1.D: Genomic control of pork fat quality and fatty acid profile. Sub-objective 1.E: Identify and validate novel single-nucleotide polymorphisms (SNP) for beef lean color stability. Sub-objective 1.F: Determine the effect of VQG' pork loin grading camera tenderness class on optimal aging time of boneless pork loins. Sub-objective 1.G: Impact of backgrounding strategies on beef carcass merit. Sub-objective 1.H: To determine the effects of replacing tylosin phosphate (Tylan�) with an essential oil containing limonene in the diet of finishing beef cattle on carcass characteristics. Objective 2: Characterize biological variation in meat quality, composition, and healthfulness traits. Sub-objective 2.A: Determine the impact of sire line on the meat quality defect characterized by a band of very pale, almost white, muscle tissue on the superficial portion of ham muscles (halo). Sub-objective 2.B: Characterize the effect of muscle metabolic efficiency, particularly in mitochondrial efficiency on beef tenderness and lean color stability attributes across varying pH classes in beef carcasses exhibiting normal lean color. Sub-objective 2.C: Determine if there are metabolomic differences between tender and tough beef across postmortem aging times. Sub-objective 2.D: Identification of differentially expressed proteins in beef longissimus steaks classified as tender with stable lean color during simulated retail display compared to steaks classified as tough with labile lean color during simulated retail display. Sub-objective 2.E: Develop technologies for measuring and predicting important traits relating to meat product quality and consistency and the biological mechanisms that control these traits. Approach (from AD-416): The overall goal of this project is to develop approaches to improve quality and healthfulness while reducing the variation in meat products. This will be accomplished by providing the red meat industries with 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 of beef, pork, and lamb. The two objectives of this project address needs in improving 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 approaches. Genetic and genomic strategies will be developed that may be combined with animal and meat management strategies to optimize quality and composition traits. Research will be conducted using 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 grade traits, tenderness, lean color stability, and fat quality. Objective 1. In order to evaluate various lamb production systems, lambs (n = 1,237) were produced by a multi-sire mating of three maternal lines (Katahdin, Polypay, and Easycare) in two mating systems: a purebred mating, system in which each maternal line was mated with rams of the same genetic line, and a terminal mating system, in which ewes were mated with Texel rams. Lambs (2,279) produced in the 2016 and 2017 lamb crops of a large sheep breeding project were harvested at a large-scale commercial packing plant that uses the VSS 2000 lamb carcass imaging system to evaluate each carcass as the hot carcasses move from the harvest floor to the chiller. The increased prolificacy of Easycare ewes relative to Polypay and Katahdin, in the low-input production system, offset the reduction in growthiness and leanness of Easycare as more pounds of carcass was produced per ewe exposed for breeding for Easycare than Polypay and Katahdin. Use of Texel rams in a terminal mating system improved growthiness, carcass leanness and carcass conformation of lambs from Easycare ewes; however, complementarity of sire breed for other growth and carcass traits should be investigated further. Using genomics to study pork fat quality, a mutation was discovered that affects the level of desaturation of fatty acids in pork fat. On-going work is being conducted to determine if other polymorphisms in the gene discovered in this work are more strongly related to the level of desaturation. This work should allow the swine industry to select for decreased desaturation, which will result in higher quality bellies that yield more, high-quality bacon. A large-scale project was conducted collaboratively with the University of Illinois and Kansas State University to determine the effect of increased carcass weights on pork quality. The heaviest group of carcasses weighed 36% more than industry average and represent the expected carcass weight after 35 years of genetic selection. Despite the increased carcass weight, there were little differences in pork quality, although, slice shear force, an objective measure of tenderness, was improved with increased carcass weight. We continued ongoing work to study the effect of backgrounding steers on fall cover crop on beef carcass quality. Relative to steers backgrounded on oats, steers backgrounded on oats + rape produced carcasses were heavier and more highly-marbled. The pork industry has identified that increasing color scores (more red) as an industry-wide goal. Most efforts in this area have addressed management of muscle pH. However, the amount of pigment present in muscle is an important driver of lean color, particularly redness. Moreover, increasing myoglobin (pigment) content in ham muscles may mitigate the Halo color defect. Thus, we conducted a genomic study for pork longissimus myoglobin content. These efforts included quantifying myoglobin content and pH in 600 pork loin samples and extracting DNA on those samples. The resulting analysis identified two quantitative trait loci for myoglobin content of pork longissimus muscle. The most highly associated QTL was located in the calcineurin gene which is associated with shifts in muscle fiber type. Objective 2. Cured ham color is of great importance in meeting consumer expectations for ham products. Recently a condition has been identified by the meat industry where a band of very pale lean tissue is present on the outside portion of ham muscles. This pale tissue does not produce normal cured color when the muscles are processed into ham products. We began working with pork processors and ham processors to quantify and characterize the phenomenon. Current results indicate the condition occurs in the vast majority of pigs regardless of production system and management and the pale portion of the muscle is higher in muscle pH and much lower in myoglobin concentration. These differences coincide with a significant shift in muscle fiber type towards white (glycolytic) fibers. Ongoing efforts include collaboration with a large pork processor to evaluate differing genetic lines on the incidence and severity of the condition. Moreover, the genomic study to identify genetic markers associated with myoglobin content may provide a strategy to mitigate the defect. We continued ongoing efforts to improve instrument grading with the beef grading camera. Implementation of the GigE upgrade to the beef grading camera resulted in a shift in beef grade distributions. At the request of USDA-AMS and beef industry leaders, we participated in a large- scale study to determine how the GigE camera should be adjusted. After several rounds of data collection and adjustment calculations, the GigE grading cameras were in line with expected results. Accomplishments 01 Identified genes associated with lean color stability in beef striploin steaks. Beef lean color is a primary determinant of consumer purchasing decisions. Cuts produced from the carcasses of some animals do not possess sufficient color life for commercial case-ready programs. USDA- ARS scientists at Clay Center, Nebraska evaluated lean color stability on steaks from a large population of cattle representing the 18 most prevalent breeds in the U.S. beef herd. An analysis of the genome of these cattle identified 417 genes associated with variation in lean color stability. These genes indicate the importance of energy metabolism, which suggest mechanisms requiring further investigation. Follow-up efforts include additional DNA sequencing to identify the specific gene alterations with the greatest effects on color as well as investigating protein and metabolite profiles to further understand the role of these genes in regulating lean color stability. 02 Identified a gene alteration that reduces dark-cutting lean beef. Dark cutting beef results in an annual loss of potential revenue for the U.S. beef industry in excess of $70 million. Dark cutting beef has long been understood to be caused by the animal having a negative energy balance before slaughter, which results in depletion of the animals muscle energy stores. However, it was not understood why a group of cattle could all be exposed to identical conditions resulting in some carcasses exhibiting the dark-cutting condition and others exhibiting �normal�, bright, cherry-red lean color. ARS scientists at Clay Center, Nebraska discovered a naturally-occurring genetic mutation in cattle that decreases the susceptibility of cattle to the dark-cutting condition. The mutation discovered in this work helps to account for much of the unexplained variation in susceptibility to dark cutting. The genetically-conserved sequence is highly-conserved across all mammals and increases susceptibility to the dark-cutting condition. Thus, the mutant, which appears to have originated in British breeds of cattle, confers the desired bright, cherry-red lean. The frequency of the favorable allele ranges from 0 to 0.7 in beef breeds and the frequency of the favorable allele is very low in Holstein steers, which are the primary source of dairy beef. Selection for the favorable allele in this gene should significantly reduce the costly occurrence of dark-cutting beef.
Impacts
(N/A)
Publications
- King, D.A., Shackelford, S.D., Schnell, T., Pierce, L., Wheeler, T.L. 2018. Characterizing the ham halo condition: A color defect in fresh pork biceps femoris muscle. Meat and Muscle Biology. 2(1):205-213.
- Cross, A.J., King, D.A., Shackelford, S.D., Wheeler, T.L., Nonneman, D.J., Keel, B.N., Rohrer, G.A. 2018. Genome-wide association of myoglobin concentrations in pork loins. Meat and Muscle Biology. 2(1):189-196.
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