Location: Meat Safety and Quality2019 Annual Report
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.
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.
1. 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.
2. 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.
3. 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.
4. 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.
5. 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.
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. https://doi.org/10.22175/mmb2018.09.0027.
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. https://doi.org/10.1093/jas/sky451.
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. https://doi.org/10.1016/j.meatsci.2018.05.021.
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. https://doi.org/10.1093/jas/skx055.