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Introduction The majority of cattle fed in commercial feedlots are processed and placed into pens without sorting into groups of uniform size and body condition. As a result of the variability in weight and condition, this management practice may lead to some cattle being fed beyond their optimal harvest point, whereas others are underconditioned and harvested prematurely, and thus fail to reach desired weight or quality grade necessary to attract available carcass premiums. Our objective was to determine if ultrasound technology could be utilized with lightweight calves as a means of predicting carcass fat thickness and yield grade outcomes. If successful, ultrasound could be a useful means of sorting cattle into uniforms groups to improve marketing.

Introduction Tenderness is one of the most important factors affecting consumers’ perceptions and acceptance of palatability. Tenderness is affected by both myofibrillar proteins and connective tissue content and quality. Both marbling and carcass maturity can have a significant effect on beef palatability, with higher consumer sensory scores generally given to USDA Choice loin steaks than to Select steaks for tenderness, juiciness, and overall palatability. Endpoint temperature can also have a significant effect, with higher endpoint temperatures generally decreasing palatability.

Introduction Foodservice managers strive to control factors that affect yield, serving cost, and palatability of beef. Beef roasts are traditionally roasted at temperatures from 325°F to 350°F for both home and institutional use. Roasts relatively high in connective tissue cooked with moist heat generally are more tender than when cooked with dry heat. Roasts cooked to 150, 160, or 170°F could be expected to have cooking losses ranging from 20% to over 40%. The issue of cooking loss led Winston Industries to develop the CVap Cook and Hold Vapor Oven (Winston Industries, Louisville, KY). CVap technology controls evaporation by creating a moist environment, which creates an opposing vapor pressure that minimizes moisture loss and should improve cooking yields. The objectives of our research were to compare the effects of moist-heat cookery in a CVap oven and dry-heat cookery in a Blodgett forced-air convection oven on cooked yield, cooked color, tenderness, and sensory attributes of beef roasts differing in connective tissue content cooked to different endpoint temperatures.

Introduction With increasing feed costs, producers may be able to utilize forage resources to help cattle gain weight before entering a high-concentrate finishing phase. In theory, heavy stocker cattle need less time on feed before slaughter compared to lighter weight cattle; however, research determining the impact of a short feeding system on product quality is limited. Therefore, the purpose of this research was to investigate the impact of a shortened, high-concentrate feeding period on carcass characteristics and meat quality traits of heavy yearling stocker cattle.

Introduction In semitropical climates in the United States, Bos indicus breeds of cattle, primarily the Brahman breed, are utilized in crossbreeding programs with Bos taurus cattle to improve productivity by increasing disease and insect resistance, heat tolerance, heterosis, and additive genetic variation. About 25% of the U.S. beef population contains some Bos indicus breeding. Numerous published reports show that tenderness of ribeye and strip loin steaks and marbling are significantly reduced in Bos indicus straightbred or crossbred cattle compared to most Bos taurus breeds. One very large study reported that heritability of tenderness and marbling is around 0.4, making it a positive trait to try to improve through selection. Only one published report has compared tenderness differences between Bos indicus and Bos taurus cattle for more than the ribeye and strip loin (longissimus muscle) and that study showed that other muscles were less tender for Bos indicus cattle. The objectives of our study were: (1) to compare carcass traits between Hereford x Angus crossbred cattle with those containing at least 50% Brahman and Sahiwal inheritance, and (2) to validate Warner-Bratzler shear force of steaks and roasts and proximate composition of 10 different muscles from these cattle.

Introduction Meat tenderness is the most important palatability attribute affecting consumers’ overall eating experience. Injection enhancement and blade tenderization have long been used to improve this important trait. Injection enhancement has been shown to improve tenderness, juiciness, color stability, and cooking yield, but not all solutions have been adequately evaluated. Thus, there is a need to conduct research on the effectiveness of common enhancement solutions. We published results from an extensive study comparing a solution of phosphate, salt, and rosemary with a solution of calcium lactate and rosemary injected by using traditional needle injection. There were no differences in Warner-Bratzler shear force values between treatments, but trained panelists scored steaks enhanced with calcium lactate and rosemary to be less tender and juicy than steaks enhanced with phosphate, salt, and rosemary. However, steaks enhanced with the phosphate solution had a higher incidence of metallic and salty off-flavors, a darker initial color, and more color deterioration. Because needle-free injection enhancement is relatively similar to traditional needle-injection enhancement with regard to food safety, it should be evaluated for its effects on meat color, instrumental tenderness, sensory traits, and yields.

Introduction Ractopamine hydrochloride (Elanco, Greenfield, IN) and Zilmax (zilpaterol hydrochloride; Intervet/Schering-Plough, Millsboro, DE) are β-adrenergic agonists approved in the United States and several other countries to increase growth rate, improve efficiency of feed utilization, and increase carcass meat yield. Zilmax has been shown to improve feed efficiency by 26% and increase hot carcass weight, longissimus muscle area, and meat yield. However, a few studies have shown that Zilmax significantly increased Warner-Bratzler shear force values (decreased tenderness).

Introduction Rapid expansion of fuel ethanol production has made available abundant supplies of distillers grains with solubles, which are well-suited as a substitute for cereal grains in finishing cattle diets. Several recently reported experiments have revealed that feeding distillers grains may have adverse effects on carcass value as a result of the tendency to produce carcasses with lower quality grades and/or higher yield grades. The effects on quality grade have been most evident in flaked-grain diets, but effects on yield grade are more or less independent of the type of grain fed. In Kansas, two common methods for processing grains are steam flaking and dry rolling. Thus, feeding cattle distillers grains with different grain processing types is an important consideration for feedlots. Our experiment was designed to evaluate meat quality and composition in heifers fed flakedcorn diets containing dry-rolled corn and/or dried corn distillers grains.

Introduction Blade tenderization has been used for decades to increase tenderness in beef cuts that are highly variable in tenderness or predicted to be “tough.” Injection enhancement also is commonly used in industry to increase tenderness, juiciness, and flavor of some beef muscles. These processes have the potential to translocate microbial organisms on the exterior to interior portions of whole muscles. One research study reported that 3 to 4% of surface bacteria are transferred into the interior of muscles but only penetrate an average of 1⁄4 inch deep into the surface. Even though the frequency of subprimal surfaces being contaminated with pathogens is low, translocation of these contaminants into the interior of subprimals by tenderization or injection procedures poses a public health risk. Microbial contamination on beef surfaces generally is eliminated during typical cooking; however, given the low infectious doses of pathogens such as Escherichia coli O157:H7, internalized contamination may survive if adequate temperatures are not reached at the center of cuts (i.e., rare and medium rare endpoints) and lead to illness. Industry groups have developed a guide, Best Practices: Pathogen Control During Tenderizing/Enhancing of Whole Muscle Cuts to minimize any hazard that may be present with such technologies.

Introduction Beef cows are culled from herds because of reproductive inefficiency, poor performance, old age, or farm downsizing due to high production costs. The National Market Cow and Bull Beef Quality Audit of 1999 reported that challenges associated with cull cow carcasses are undesirable dressing percentages and meat yields. Since 1999, an increasing number of producers are either selling cows in better physical condition or feeding cows a high concentrate ration for 50 to 100 days prior to harvest. According to the 2007 audit, cow carcasses were heavier and leaner and had more desirable muscle and fat color scores than in 1999. Although these improvements are positive steps toward increasing the value of cull cows, use of growth promoting agents, such as steroid implants and β-adrenergic agonists, can increase muscling and leanness more efficiently than feeding a concentrate ration alone. Currently, there are two β-agonists on the market for use in beef cattle in the United States: Optaflexx (ractopamine hydrochloride; Elanco, Greenfield, IN), a β1-agonist, and Zilmax (zilpaterol hydrochloride; Intervet Inc., Millsboro, DE), a β2-agonist. These growth promotants have been studied individually and in combination with implants (primarily in young steers and heifers), but no research published to date has investigated feeding a sequence of these growth promoting agents. Therefore, our objective was to investigate effects of feeding Optaflexx for 25 days followed by Zilmax for 20 days plus a 3-day withdrawal on cull cow performance, carcass traits, and meat quality.

Marbling continues to be a major factor affecting profitability for beef producers, processors, retailers, and restaurateurs. However, feeding animals to ‘fatten’ is quite inefficient, requiring about 2.25 times more energy than is needed for producing lean muscle. For the cattle feeding industry to be sustainable in the future, increases in marbling must be accomplished without increasing days on feed, slaughter age carcass weight, and fatness and without sacrificing feed efficiency and carcass cutability.

Case-ready meat provides many benefits, including quality and safety. Meat packaged in high-oxygen (HiO2) modified atmosphere packaging (MAP) has a desirable bright red display color but may have increased offflavors and decreased tenderness. According to several international research reports, steaks aged and packaged in HiO2 MAP had more off-flavor, including warmed-over flavor, and were less tender and juicy than steaks aged in vacuum packaging (VP). Research at Kansas State University found that injection-enhanced beef quadriceps muscles packaged in HiO2 MAP were less tender and had more offflavors than those in ultra-low oxygen MAP. Detrimental effects of O2 on tenderness might be caused by protein oxidation. Oxidation of beef muscle proteins early postmortem inactivates the primary enzyme (μ-calpain) necessary to break down proteins postmortem, which results in decreased myofibrillar proteolysis and limited tenderization.

Gene mapping and discovery programs have resulted in the detection of numerous DNA ‘markers’ for various beef cattle production traits. Prior to commercializing genetic markers, it is important to validate their purported effects on the traits of interest in different breeds and environments, and assess them for correlated responses in associated traits. One of the biggest challenges in achieving this objective is the availability of cattle populations with sufficient phenotypic data to assess the association between various traits and newly discovered genetic markers. Results from such validation studies to date have not been widely published and genetic marker tests sometimes may be commercialized prior to the collection of field validation data. In addition, conflicting reports about some commercially available markers, as well as the recognized occurrence of well-proven bulls with a high EPD for a given trait but carrying two copies of the “wrong” (unfavorable) marker for that trait, have made some producers wary of investing in DNA-based testing. Producers want to know whether DNA-based tests perform in accordance with the claims of the marketing company and are interested in third-party, independent validation of these tests. The objective of this study was to validate three commercially-available genetic tests (GeneSTAR Quality Grade, GeneSTAR Tenderness, and Igenity TenderGENE).

Crossbred Hereford × Angus calves (n = 103) were used to determine the effects of early weaning on feedlot performance of bulls and steers. Treatments were: 1) early-weaned (117 days of age) bulls, 2) early-weaned steers, 3) normal-weaned (220 days of age) bulls, and 4) normal-weaned steers. Earlyweaned calves were placed on a grower ration at an average age of 134 days and on a finishing ration at 182 days of age. Normal-weaned calves were placed on a finishing ration at 242 days of age. Weight, feed intake, and ultrasound measurements were recorded during the feeding period. Three early-weaned cattle were removed due to chronic bloat, and four early-weaned cattle died in the feedlot. The feedlot period was terminated at either 358 or 387 days of age. Early-weaned cattle had greater average daily gains early in the feedlot period, but normal-weaned cattle had greater gains later in the feedlot period. Excluding the initial weight at 117 days of age, earlyweaned cattle maintained heavier weights throughout the feeding period. Bulls had greater average daily gains until feedlot entry of normal-weaned calves, but steers had greater average daily gains later in the feedlot period, resulting in similar final weights. For early-maturing British-type cattle, early weaning resulted in heavier final weights, but it may not be the most viable management strategy because of disadvantages in animal health. Overall, there was no growth-performance advantage for leaving males intact, suggesting that the implant regimen used for these steers was sufficient to compensate for the expected loss in performance when bulls are castrated. Introduction

Crossbred Hereford × Angus calves (n = 103) were used to determine the effect of early weaning on carcass and ribeye (longissimus muscle) characteristics of bulls and steers. Treatments were: 1) early-weaned (117 days of age) bulls, 2) early-weaned steers, 3) normal-weaned (220 days of age) bulls, and 4) normal-weaned steers. Cattle were harvested at 360 and 389 days of age. At 36 hours postmortem, carcass quality and cutability were measured. Ribeye steaks were aged 14 days and scored for color, Warner-Bratzler shear force, and sensory panel evaluations. Carcasses from early-weaned cattle had greater dressing percentages, heavier weights, greater fat thicknesses, and higher numerical USDA Yield Grades (lower cutability). They also had more marbling and greater USDA quality grades, but had similar longissimus color, shear force, and sensory panel scores, compared with those of normal-weaned cattle. Bulls had greater dressing percentages, but had similar carcass weights to steers. Bull carcasses had less fat thickness and greater ribeye areas, resulting in lower numerical USDA Yield Grades (higher cutability) than steers had. They also had less marbling, darker color, and lower USDA quality grades than steers did. Longissimus muscles from bulls were darker, had greater shear forces, and had lower sensory panel tenderness scores than those from steers. For early-maturing British-type cattle, early weaning is a viable management strategy to produce heavier, higher-quality carcasses than those of normalweaned cattle. Carcasses from early-weaned cattle are fatter and have lower cutability. For a non-implant “natural” market, bulls could be an alternative for producing high-cutability carcasses. Steaks may be less tender, however, and pre-harvest management must be optimized to reduce dark-cutting carcasses.

Meat retailers have reported bone marrow discoloration to be a problem, especially in modified-atmosphere packages (MAP). To evaluate causes of bone marrow discoloration in different beef bones and packaging systems, 36 beef arm bones, ribs, shoulder blades, and thoracic vertebrae from USDA Select and Choice carcasses were obtained from a commercial abattoir, cut into 1-inch-thick sections at 4 days postmortem, and packaged into 1) polyvinyl chloride film (PVC) overwrap; 2) high-oxygen (80% O2, 20% CO2) MAP; or 3) ultra-low-oxygen (70% N2, 30% CO2) MAP. Packages were displayed under continuous fluorescent lighting for 4 days at 35.6 F. Ribs, shoulder blades, and thoracic vertebrae packaged in PVC and high-oxygen MAP developed undesirable gray or black discoloration during display. In ultra-low-oxygen MAP, mean visual-color scores were acceptable throughout display. The a* values (larger values equate to redder color) for ribs, shoulder blades, and thoracic vertebrae decreased (P

To evaluate how antioxidants might prevent bone marrow discoloration, beef lumbar vertebrae held at 35.6°F for 6 or 14 days postmortem before packaging were cut into 1inch-thick sections and packaged into 1) PVC overwrap; 2) high-oxygen (80% O2, 20% CO2) modified atmosphere packages (MAP); or 3) ultra-low-oxygen (70% N2, 30% CO2) MAP. Before packaging, bones were treated with: no treatment application (control); 1.25% or 2.5% ascorbic acid; 0.1% or 0.2% rosemary; or a combination treatment of 0.15% OriganoxTM + 0.3% ascorbic acid. Packages were displayed under continuous fluorescent lighting for 4 days at 35.6°F. Untreated lumbar vertebrae and those treated with 0.1 or 0.2% rosemary discolored to gray or grayish-black, as measured by visual color scores and instrumental a* values, in PVC and high-oxygen MAP. The 1.25% ascorbic acid and 0.15% OriganoxTM + 0.3% ascorbic acid were able to maintain desirable color scores through day 2 of display in PVC and highoxygen MAP, but not after 4 days. The 2.5% ascorbic acid treatment was most effective in preventing discoloration and maintaining initial color in both PVC and high-oxygen MAP. In ultra-low-oxygen MAP, the 1.25% ascorbic acid treatment was as effective as the 2.5% ascorbic acid treatment in preventing bone marrow discoloration. In general, discoloration tended to be greater in bones held 14 days postmortem before packaging than in those held 6 days. Ascorbic acid treatments, particularly the 2.5% application, were effective in preventing bone marrow discoloration. Introduction

Previous studies have shown that citrate has the potential to inhibit phosphofructokinase (PFK), a key enzyme in post-mortem glycolysis. The objective of our study was to determine the effects of oral administration and feeding of citrate or acetate to pigs on post-mortem glycolysis, pH, and pork quality attributes. In Experiment 1, citrate, acetate, or water was orally administered to 30 pigs 45 min before stunning (electric plus captive bolt). In Experiment 2, citrate or acetate was fed to 30 gilts in 454 g of feed 60 min before stunning. Ante-mortem treatment had no effect (P > 0.05) on muscle pH or post-mortem concentrations of glycolytic metabolites: glucose-6 phosphate, fructose-6 phosphate, fructose-1,6 bisphosphate, glyceraldehyde-3 phosphate, dihydroxyacetone phosphate, or lactate. Minor, but inconsistent, differences in quality attributes were found in longissimus chops and inside and outside semimembranosus quality attributes among treatments (P>0.05). The reason for the lack of PFK inhibition is not known. Glycolytic-metabolite data indicate that PFK was a main regulatory enzyme in post-mortem muscle.

Color characteristics were evaluated on 48 pork backbones. After 6 d postmortem, six 1inch-thick sections of lumbar vertebrae were cut from each backbone. Lumbar vertebrae were treated with different concentrations of ascorbic acid, with combination treatments of ascorbic acid and natural antioxidants, or left untreated. Bones were packaged in one of three systems: high-oxygen modifiedatmosphere packaging (MAP), ultra-lowoxygen MAP, or polyvinyl chloride (PVC) overwrap trays. Bones were visually evaluated by a trained panel on d 0, 1, 2, 3, 4, 5, and 8. Lightness (L*) was also measured on d 0, 2, and 8 of display. After 8 d of display, antioxidant-treated bones packaged in highoxygen MAP were more desirable than those in PVC overwrap trays. Bones packaged in ultra-low-oxygen MAP became less desirable over 8 d of display. Solutions of 1.875% and 2.50% ascorbic acid yielded the most desirable color after 8 d for bones in high-oxygen MAP and in PVC overwrap trays. Bones treated with 1.875% or 2.50% ascorbic acid tended to have lighter color (higher L*) on d 8 for high-oxygen MAP and PVC overwrap trays, whereas an overall difference was not observed for lightness for bones packaged in ultra-low-oxygen MAP.

Our objective was to determine the effects of endpoint temperature, cooking method, and marbling on Warner-Bratzler shear force (WBSF; an objective method for determining tenderness) of three beef muscles. Eighteen subprimals of a muscle containing low content of connective tissue, longissimus lumborum (strip loin), and two muscles containing a high content of connective tissue, biceps femoris (bottom round) and deep pectoralis (brisket), were selected from USDA Select and Choice (Certified Angus Beef) carcasses. After 14 days of aging, subprimals were frozen, fabricated into steaks, and stored frozen until cooking. Steaks were assigned to one of two cooking methods, the Magikitch’n electric belt grill (a rapid conduction method) or a water bath (a slower, convection method); and one of nine endpoint cooking temperatures, 104, 113, 122, 131, 140, 149, 158, 167, or 176°F. According to WBSF results, optimum tenderness for the strip loin occurred around 131°F. Higher marbling protected tenderness at higher endpoint temperatures. Tenderness increased in bottom round and brisket muscles as endpoint temperature increased from 104 to 140°F, then tenderness decreased as endpoint temperature rose from 149 to 176°F. Endpoint temperature was the only significant factor affecting bottom round tenderness. Steaks cooked in the water bath had higher WBSF and, therefore, were less tender than those cooked on the belt grill. This was true for both the strip loin and brisket. The effect of increasing endpoint temperature on WBSF of the strip loin was different than for the bottom round and brisket.

Appreciation is expressed to the Beef Checkoff for funding this project, National Cattlemen’s Beef Association for coordination, and to Cryovac Sealed Air Corporation for providing packaging materials. The authors would like to acknowledge the assistance of J. W. Stephens, J. R. Davis, S. L. Stroda, S. Lowak, and A. Jenkins. Department of Human Nutrition. Department of Statistics. National Cattlemen’s Beef Association, Centennial, CO. Cattlemen’s Day 2003

Carcass data and Warner-Bratzler shear force (WBSF) data on strip loin steaks were collected from nearly 8,500 cattle in contemporary groups of progeny from the more popular sires in 14 different beef cattle breeds in the Carcass Merit Traits project funded by Beef Checkoff dollars, the breed associations, and MMI Genomics. In addition, trained sensory panel evaluations were conducted on over 2,500 strip loin steaks from contemporary groups of progeny from five sires included in the DNA marker validation component of the project. The correlation between WBSF and tenderness scored by the trained sensory panel was -0.82, indicating that as WBSF increased, tenderness scored by the sensory panel decreased. Our results showed that a WBSF value of ≥ 11.0 lb generally results in a sensory score of slightly tough or tougher. In this study, 22.8% of the cattle had WBSF values ≥ 11.0 lb and 26.3% had sensory scores of slightly tough or tougher. The phenotypic range of WBSF means for sires within breeds ranged from 1.9 to 6.6 lb. The phenotypic range of WBSF means across breeds was 8.9 lb, whereas the range among sires across breeds was a dramatic 14.4 lb. The phenotypic range for flavor intensity scores among sires within and across breeds was much smaller than for tenderness, with juiciness scores being intermediate. The 40 widely used sires that produced progeny with steaks that were unacceptable in tenderness in this study might be expected to be sires of several thousand bulls used in commercial herds. This demonstrates that seedstock producers should aggressively utilize sires that have genetics for tender meat.

The infraspinatus muscle (top blade) from the chuck clod, the gluteus medius muscle (top sirloin) from the sirloin, and the psoas major muscle (tenderloin) from the loin were obtained from 140 Aand B-maturity carcasses with either low-Slight or Small marbling and with either normal pH (5.7 or less) or high ultimate pH (6.0 or higher) to evaluate factors that could cause livery flavor in cooked beef. Muscles were aged for 7, 14, 21, or 35 days. A highly trained, flavor-profile sensory panel evaluated charbroiled steaks from these muscles. Approximately 8% of all sensory panelist judgments were scored to have some livery flavor. Numerous statistical interactions were found among traits, which made it difficult to make clear conclusions. In general, marbling and aging time had little direct effect on livery flavor, and livery flavor was not related to raw muscle lipid oxidation.

We explored the mechanism(s) of calcium-induced tenderization in calciumenhanced beef muscle. At 72 hours postmortem, we injected (9% by weight) beef strip loins (n=15) with 0, 0.05, 0.1, 0.2, or 0.4 M calcium chloride (CaCl2) with and without 0.05 M zinc chloride (ZnCl2), and they were then aged until 15 days postmortem. WarnerBratzler shear force peak values indicated that addition of ZnCl2 drastically inhibited tenderization; however, enhancement with CaCl2 still tended to reduce shear values (P=0.07; 0.55 kg) when ZnCl2 was present. In the absence of ZnCl2, the 0.2 and 0.4 M CaCl2 treatments were 18.9 and 32.1% more (P

We pooled the mechanical probe data from two experiments to develop regression equations to predict beef longissimus tenderness. Fifty-three USDA Select strip loins were evaluated at 2 days postmortem with three mechanical probes to predict trained sensory panel (TSP) tenderness and WarnerBratzler shear force (WBSF) of cooked steaks aged 14 days. The sharp needle, sharp blade, and plumb bob probes were correlated to TSP tenderness (r=-0.51, -0.45, and -0.35, respectively) and WBSF (r=0.56, 0.53, and 0.36, respectively). Regression equations developed from sharp needle, sharp blade, and plumb bob probe measurements and L* (lightness) values accounted for 49, 50, and 47% of the variation in TSP tenderness. The predicted values of equations were also used to classify the strips as tough or tender, and this classification was compared to the actual TSP tenderness classification. Of the steaks predicted to be tender by the equations using the sharp needle, sharp blade, and plumb bob probes and WBSF 88, 88, 84, and 87%, respectively, were actually tender according to TSP. The sharp needle, sharp blade, and plumb bob probe prediction equations were comparable to WBSF in classifying carcasses into sensory panel determined tenderness groups, and they were superior to WBSF in simplicity and cost. Introduction

Introduction Combined microwave and convection cooking has gained popularity in the last 20 years because of more accurate heat control and more efficient use of energy. Combination microwave/convection cooking allows for more rapid cooking, but it does not have the same even heat distribution as convection cooking. Cooking is a critical stage when preparing meat. The main factors to consider during cooking are: temperature on the surface of meat, internal temperature throughout, and the method of heat transfer. Temperature on the surface and method of heat exchange primarily affect surface color and aroma, whereas internal temperature affects protein structure and flavor as well as aroma. At any temperature above 230°F, Maillard browning reactions start to occur and give meat its typical brown, caramelized appearance; however, high humidity prevents Maillard browning from occurring and dilutes flavor and odor components. All sensory attributes can, therefore, be significantly influenced by the cooking technique used. Different cooking methods allow for tenderness, flavor development, and color changes, all of which can be either acceptable or unacceptable for consumers.

We cooked steaks from two muscles; outside round (biceps femoris), and strip loin (longissimus lumborum) with an electric belt grill. Biceps femoris steaks had higher Warner-Bratzler shear force (WBSF), connective tissue force (WB Cforce), and myofibrillar force (WB Mforce) values than longissimus lumborum steaks. Holding biceps femoris steaks at 144°F after cooking increased WB C-force (P

We investigated mechanical force measurements on uncooked longissimus muscle as a means to predict WarnerBratzler shear force (WBSF) and trained sensory panel tenderness (SPT) of cooked strip loin steaks. Uncooked steaks from 24 USDA Select strip loins (IMPS 180) were evaluated at 2 and 14 days postmortem using plumb bob and needle probe devices attached to an Instron Universal Testing Machine. Cooked steaks aged 14 days were then evaluated for WBSF and SPT. Regression models to predict SPT from needle probe and plumb bob measurements individually taken at 2 days postmortem had R of 0.54 and 0.51, respectively. Combining needle probe and plumb bob measurements resulted in an R of 0.76; however, when quadratic terms for both variables were in the model, R was 0.80. Regressing needle probe and plumb bob measurements at 2 days postmortem with WBSF produced R of 0.51 and 0.45, respectively. When linear terms of both probes were combined, R improved to 0.77. An equation to predict WBSF including both the linear and quadratic terms of needle probe and plumb bob measurements resulted in R of 0.84. Using plumb bob and needle probe combined on uncooked longissimus muscle at 2 days postmortem can predict cooked WBSF and SPT of strip loin steaks aged for 14 days. (

Our study evaluated the effectiveness of the Beef Empire Days carcass index in ranking beef carcasses compared to rankings based on carcass prices. Two price sets were used: the average prices between January 1998 and June 2001, and a short-range price determined from the average prices between April and September of 2001. Additionally, carcass data from the top live-placing cattle were compared to the data of the highest indexing carcasses. The live show judges were very accurate in selecting for ribeye size. However, they selected cattle that were fatter, but did not marble as well as the high indexing carcasses. Changes that might improve the index are identified. However, the Beef Empire Days index ranked carcasses moderately well compared to the pricing system.

A study was conducted to determine if excised, cold-shortened muscle improves in tenderness with refrigerated aging. Changes in muscle tenderness due to cooking rates were also evaluated. Beef ribeye and shoulder clod muscles from the left side of 12 carcasses were removed 45 min postmortem and placed in an ice bath to induce cold shortening. Corresponding muscles from the right side were chilled conventionally on the intact side. One-inch steaks from these muscles were either frozen at 24 hours or aged for 14 days at 40oF before being cooked and analyzed. Steaks were analyzed raw, or cooked to 160oF internally in a oven at 200 (SLOW) or 500°F (FAST). Sarcomere length (degree of contraction), tenderness, and the extent of degradation of structural proteins were measured. Rapid chilling caused severe muscle contraction, which had a dramatic toughening effect. At 24 hours, the coldshortened muscle showed less protein degradation than conventionally chilled muscle. After aging 14 days, tenderness had improved and protein degradation had occurred in both cold-shortened and conventional muscles, but degradation was still less in cold-shortened muscles. The improvement in tenderness and the increase in protein degradation from 1 to 14 days were equal between cold-shortened and conventional chilling treatments but the coldshortened muscles remained tougher. FAST cooking resulted in greater cooking losses and greater sarcomere shortening than SLOW cooking. Cooking rate did not affect the tenderness of ribeye steaks, but SLOW cooking improved the tenderness of shoulder clod steaks that are higher in connective tissue. Extreme chilling conditions, which induce cold shortening, may reduce protein degradation beyond the effect of shortening. Although aging improved the tenderness of cold-shortened muscles, they remained tougher than their conventionally chilled counterparts.

Twenty-four USDA Select strip loins (IMPS 180) were aged (32°F) until 14 days postmortem and fabricated into longissimus muscle (strip loin) steaks (1-in. thick). Then, steaks were either cooked or stored at −20°F for an additional 17 days before they were thawed and cooked. Cores and sensory panel samples were removed from the medial, center, and lateral sections of each steak and locational identify maintained. In addition, a random composite of cubes from an entire steak was used for a sensory panel evaluation. Previously frozen steaks had lower Warner-Bratzler shear force (WBSF) values, less cooking loss, and a shorter cooking time than fresh (non-frozen) steaks; however, no difference was found for combined thawing and cooking loss. Cores from the medial section of steaks had lower WBSF values than cores from the center section. A sensory panel found that the medial section was more tender than the lateral section and had less detectable connective tissue than the center or lateral sections or samples taken at random. The center and random treatments were juicer than the lateral section. Highest correlations between sensory panel tenderness and WBSF were obtained when the medial and lateral sections were averaged (r=−0.74, r=−0.69) and when all three sections were averaged (r=−0.70, r=−0.69) for fresh and frozen WBSF steaks, respectively. Freezing lowered WBSF values and the medial section of the steak was the most tender. An awareness of these results and potential procedural artifacts must be considered when handling and sampling steaks, and interpreting results.

Beef strip loins were assigned to one of 11 treatments that included injection marination (10% by weight) with three calcium salts at three molar concentrations, a distilled water control, and a nonmarinated control. The effects of calcium salt and concentration were tested for retail display color life, tenderness and sensory traits, and microbial growth. Calcium lactate marinated steaks had longer color life and less microbial growth than those treated with calcium chloride or calcium ascorbate. Increasing molar concentration (.1M to .2M to .3M) caused faster color deterioration, and did not significantly improve microbial inhibition. All calcium treatments improved tenderness; however, calcium chloride treatments induced off-flavors. Considering a whole system approach that accounts for color life, microbial inhibition, shear force, and sensory traits, we recommend injecting beef longissimus with 10% of a .1M solution of calcium lactate, and do not recommend other calcium salts or concentrations.

Three experiments using 63 pigs were conducted to determine if infrared thermography could segregate pigs based on subsequent pork quality. Pigs were subjectively classified as either “hot” or “normal” based on infrared surface temperature of the loin region prior to slaughter. In the first experiment 18 market weight pigs were transported, imaged by infrared thermography and slaughtered immediately after 1 to 4 h of lairage. Differences in meat quality were detected; hot pigs had lower a* (less red) and chroma (less intense red color) values, and higher hue angle (less red/more yellow) values, all of which indicate paler muscle color. In the second experiment, 27 market weight pigs were transported, held in lairage for 12 to 16 h, imaged by infrared thermography, and then slaughtered. In the third experiment, 18 market weight pigs were transported, imaged by infrared thermography, held in lairage for 12 to 16 h, and then slaughtered. Regardless of the time infrared images were taken, no meat quality differences between hot and normal pigs were detected when pigs were held in lairage for 12 to 16 h. These data suggest that measurement of live animal surface temperature by infrared thermography may allow for detection of poor meat quality if pigs are slaughtered without extended lairage.

We evaluated the interrelationships among carcass characteristics of steers and heifers selected from commercial feedlots for competition in the Beef Empire Days live and carcass contests. Because judging criteria are weighted heavily on cutability, the majority of cattle entered were trim and muscular. Within this highly selected group, heifer carcasses had larger ribeye areas, lower hot carcass weights, more ribeye area/100 lbs. of hot carcass weight, and a higher percentage of kidney-pelvic-heart fat than steers. However, steers graded USDA Choice or better 4% more often than heifers. Ribeye area, ribeye area/100 lbs. of hot carcass weight, and percentage of kidneypelvic-heart fat increased as dressing percentage increased; however, 12 rib fat thickness had no effect on dressing percentage. Percentage of carcasses grading USDA Choice or better tended to decrease with improved dressing percentage. As 12 rib fat thickness increased, ribeye area and ribeye area/100 lbs. of hot carcass weight decreased whereas percentage of kidneypelvic-heart fat and hot carcass weight of steers increased. As 12 rib fat thickness increased up to 0.50-0.59 inches, the percentage of cattle that graded low Choice or higher increased, but more finish did not result in further increase in percentage of low Choice or better. This study indicates that ribeye area is more closely related to economically important carcass characteristics in trim, muscular cattle than previously identified.

We used an electric belt grill, a forced-air convection oven, and an electric broiler to cook 170 bottom round, 142 brisket, 177 top sirloin, 176 strip loin, and 136 eye of round steaks from USDA Select carcasses to determine the effects of cooking method and muscle on shear force values, cooking traits, and repeatability of duplicate measurements. All cooking treatments allowed differences to be detected (P

Introduction Approximately 16% of cattle slaughtered in the United States are cows. When these cows are removed from the herd, they are typically in thin condition. Steaks from these cows are considered tougher than those from young steers and heifers but could potentially be improved with alternative management practices, such as high-concentrate feeding. Feeding high-concentrate diets, implanting, and feeding β-agonists prior to harvest have been shown to improve performance and carcass meat yields. However, the effect on steak tenderness of feeding Zilmax (zilpaterol hydrochloride; Intervet Inc., Millsboro, DE) to mature cows is unknown. Therefore, the objective of this study was to determine the effects of concentrate feeding, implanting, and feeding Zilmax on tenderness of strip loin and knuckle steaks from cull cows fed for 70 days.

Two groups of grain-finished, crossbred Charolais steers were utilized to determine the effects of post-bleeding vascular infusion on dressing percentages, USDA quality and yield grades, Warner-Bratzler shear force values, and flavor. Nine steers from one group of 18 were infused with a solution containing sugars, sodium chloride, and a phosphate blend (MPSC), and the remaining nine steers served as noninfused controls. Nine in the second slaughter group of 18 were MPSC-infused, and nine were infused with the MPSC solution plus 500 ppm vitamin C (MPSC+C). The MPSC cattle had a 2.9% higher mean dressing percentage (P .05) on Warner-Bratzler shear force or USDA quality and yield grades. Results from a descriptive flavor profile sensory panel showed some significant differences in flavor profile characteristics, but these differences were small and inconsistent. Vascular infusion with MPSC or MPSC+C increased carcass weights, had few effects on USDA quality or yield grades or shear force, and had no consistent effects on flavor profile characteristics of cooked beef.

Hereford × Angus carcasses were infused with a solution of either sugar/phosphate or calcium chloride immediately after exsanguination to determine effects on color stability during retail display. A calcium chloride solution darkened the cuts and reduced color stability. A sugar/phosphate blend made steaks appear lighter red (more desirable), and their color stability was equal to that of the noninfused control.

Because the beef industry commonly uses marbling as an indicator of meat palatability, determining the most cost effective methods of increasing quality grade in cattle is a high priority. Previous research showed that weaning calves at around 90 instead of 200 days of age can be beneficial in reducing cow production costs and increasing marbling in feedlot steers. Other studies demonstrated that high levels of vitamin A inhibit development of intramuscular fat. Vitamin A restriction is used commonly in Japanese cattle to increase marbling scores; this stimulated interest in applying this restriction in U.S. beef production systems. However, little research has been conducted to determine the effect that vitamin A restriction might have on other meat quality components. Therefore, our objective was to determine the effects of feeding high and restricted levels of vitamin A to early and traditionally weaned calves during finishing on color display life, lipid oxidation, and sensory attributes of two beef muscles.