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ARS Home » Plains Area » Clay Center, Nebraska » U.S. Meat Animal Research Center » Meat Safety and Quality » Research » Research Project #423446


Location: Meat Safety and Quality

2014 Annual Report

Objective 1: Develop strategies to manage and improve variation in meat quality and composition traits. 1.1: Determine the temperature and pH profiles for optimal quality of modern pork. 1.2: Develop genetic markers for pork lean color stability, tenderness, water holding capacity, intramuscular fat content, sarcomere length, and postmortem proteolysis. 1.3: Evaluation of plasma glucose and lactate levels at exsanguination as predictors of meat quality attributes. 1.4: Evaluate the relationships between mitochondrial abundance and efficiency and animal variation in beef lean color stability. 1.5: Determine seasonal variation in fatty acid profile of belly adipose from first-pull and run-out hogs fed diets differing in fatty acid profile. 1.6: Determine variation in fatty acid profile of belly fat from first-pull and run-out gilts, barrows, and immuno-castrated barrows. Objective 2: Develop non-invasive technology to improve meat quality, composition, and healthfulness traits. 2.1: Develop regression equations for prediction of ribeye (longissimus) area and other value determining characteristics using the laser-enhanced VBG2000 beef carcass grading camera. 2.2: Determine the effect of light source on robustness of regression equations for prediction of marbling score using the laser-enhanced VBG2000 beef carcass grading camera. 2.3: Develop regression equations for prediction of beef fatty acid profiles with on-line visible and near infrared (VISNIR) spectroscopic evaluation of the ribeye (longissimus) and subcutaneous fat during beef carcass grading. 2.4: Develop regression equations for on-line prediction of fatty acid profiles of pork belly fat with VISNIR spectroscopy. Objective 3: Improve product quality and healthfulness, and food animal growth and production efficiencies, through development of alternatives to conventional antimicrobials utilizing novel metagenomic and microbial genomic technologies.

The effects of the interaction of muscle pH and temperature decline on various pork quality traits will be determined. Genetic markers will be identified that can be used to optimize various pork quality traits. Plasma glucose and lactate levels at exsanguination will be evaluated as predictors of meat quality traits. Mitochondrial abundance and efficiency will be evaluated as mechanisms controlling variation in lean color stability. Season, marketing group, and immuno-castration will be investigated as sources of variation in pork fat quality. The USMARC beef carcass grading camera accuracy will be enhanced by developing prediction models using more stable light sources and laser-enhanced placement adjustments. Healthfulness and quality of beef and pork will be improved by developing visible and near-infrared prediction of fatty acid profile of lean and fat. The effect of alternatives to antibiotics such as lysozyme for young piglets on growth and efficiency will be determined. In addition, the potential for improvement of product quality and efficiency will be determined for diet modified gut microbial composition.

Progress Report
Both objectives were advanced this year. For Objective 1, a comprehensive study of heat stress and zilpaterol feeding was initiated to evaluate the impact on production traits, measures of heat stress, and carcass yield and quality. In addition, the impact of extended aging time on consumer evaluation of steak palatability will be determined. A study of the impact of extended aging time on steak tenderness of ribeyes from cattle fed ractopamine was initiated. A study of the impact of feeding cattle beta-agonists on the lean color stability of retail meat packages was initiated and will include measurements at 1, 4, 7, and 11 days of retail display. A study was started to evaluate the relationship between ribeye tenderness and tenderness of top sirloin and bottom round cap muscles after 7, 14, 21, and 35 d postmortem aging time. Under Objective 2, a live animal imaging system was installed at our feedlot and preliminary data were collected to begin developing a prediction of number of days on feed required to optimize marketing of animals. In addition, this system was used to measure stride length to contribute to evaluation of animal mobility for other experiments.

1. Development of a robust regression equation for tenderness prediction for the beef carcass grading camera system. Variation in beef tenderness results in consumer dissatisfaction. Therefore, many companies desire technology to identify carcasses that excel in tenderness. ARS scientists from Clay Center, Nebraska, worked with the instrument manufacturer and the beef industry to develop a robust regression equation for the system that has obtained USDA-AMS approval for tenderness prediction at the time of beef carcass grading. For the first time, this technology provides the beef processing industry with the ability to measure USDA quality grade, yield grade, and tenderness with the same instrument.

2. Association between mitochondrial abundance and efficiency and the dark ribeye color in beef. Long-term stress can deplete the muscle of glycogen in beef cattle resulting in abnormal pH decline during the onset of rigor mortis. The result is an unattractive dark-colored ribeye which is associated with off-flavors, decreased tenderness, and rapid spoilage, thus, carcasses displaying this condition are severely discounted in price. ARS scientists at Clay Center, NE, demonstrated that muscles from carcasses exhibiting the dark ribeye condition have greater concentrations of mitochondria than contemporary carcasses from the same production lot displaying normal ribeye color. Moreover, carcasses displaying the dark ribeye condition were found to have different muscle physiology than their normal cohorts and are less able to deal with stress. This is the first identification of a pre-existing difference in live animals that produce carcasses with dark colored ribeyes. This knowledge may lead to technology to reduce or eliminate incidence of the dark ribeye condition.

3. Novel food safety interventions could be applied to subprimals without deleterious effects on meat quality. Blade tenderization is a common tenderization strategy utilized by beef processors to increase palatability and, thus, consumer satisfaction of beef steaks. However, because of increased food safety risk, processors seek new technology to ensure product safety prior to blade tenderization. ARS scientists at Clay Center, NE, determined that three novel food safety interventions had minimal effects on beef lean color, lean color stability, and flavor, when applied to cuts of beef prior to blade tenderization and steak cutting. These novel antimicrobial interventions could be used to improve food safety of blade tenderized products without negatively affecting product quality.

Review Publications
Casas, E., Duan, Q., Schneider, M.J., Shackelford, S.D., Wheeler, T.L., Cundiff, L.V., Reecy, J.M. 2014. Polymorphisms in the calpastatin and mu-calpain genes associated with beef iron content. Animal Genetics. 45(2):283-284. DOI: 10.1111/age.12108.
King, D.A., Shackelford, S.D., McDaneld, T.G., Kuehn, L.A., Kemp, C.M., Smith, T.P., Wheeler, T.L., Koohmaraie, M. 2012. Association of genetic markers in cattle receiving differing implant protocols. Journal of Animal Science. 90:2410-2423.
Shackelford, S.D., King, D.A., Wheeler, T.L. 2012. Chilling rate effects on pork loin tenderness in commercial processing plants. Journal of Animal Science. 90:2482-2849.
Grayson, A.L., King, D.A., Shackelford, S.D., Koohmaraie, M., Wheeler, T.L. 2014. Freezing and thawing or freezing, thawing, and aging effects on beef tenderness. Journal of Animal Science. 90(6):2735-2740.