Variation in palatability and biochemical traits within and among eleven beef muscles

Comparison of meat quality between eland (Taurotragus oryx) and cattle (Bos taurus) raised under similar conditions

Physical, chemical and sensory characteristics of meat were compared between non-domestic eland (Taurotragus oryx) bulls (n=6) and domestic Fleckvieh (Bos taurus) bulls (n=6) which were finished under controlled conditions of feeding and management. Musculus longissimus lumborum from eland were darker and less yellow in colour, with a higher pH24 and lower contents of intramuscular fat and total collagen, compared to cattle. Contents (mg/100 g muscle tissue) and proportions (g/100 g of FA determined) of SFA and MUFA were higher (P<0.01) in cattle. Although the proportion of total PUFA were higher (P<0.001) in eland, contents of PUFA were similar between species. Meat from cattle was consistently scored higher (P<0.05) for sensory texture characteristics, juiciness, flavour, and overall acceptance. We concluded that bulls of eland provided low-fat meat with a beneficial fatty acid composition from a human nutrition perspective, but with lower sensory scores, compared to bull beef.

Color stability and tenderness variations within the gluteus medius from beef top sirloin butts

Beef top sirloin butts (n=48) from USDA quality grade (QG; upper 2/3 US Choice vs. US Select) and yield grade categories (YG; 1 and 2 vs. 4 and 5) were aged 14 days, GM steaks were cut, with 2 steaks removed from the anterior (ANT), middle (MID) and posterior (POST) sections of the GM. One steak from each section was cut into lateral (LAT), central (CENT) and medial (MED) portions, packaged aerobically, and displayed for 7 days, whereas the second steaks were cooked to 71°C for WBSF. Top Choice-steaks were redder and more yellow (P<0.05) than Select steaks during display. Cooking losses were greatest (P<0.05) in the MED, and least (P<0.05) in the CENT, portions of GM steaks. Neither QG nor YG category affected WBSF, but differences within the GM were found for (P<0.05) WBSF. Results of this experiment indicate tenderness and color stability gradients exist within the GM.

Alternative pre-rigor foreshank positioning can improve beef shoulder muscle tenderness

Thirty beef carcasses were harvested and the foreshank of each side was independently positioned (cranial, natural, parallel, or caudal) 1h post-mortem to determine the effect of foreshank angle at rigor mortis on the sarcomere length and tenderness of six beef shoulder muscles. The infraspinatus (IS), pectoralis profundus (PP), serratus ventralis (SV), supraspinatus (SS), teres major (TM) and triceps brachii (TB) were excised 48 h post-mortem for Warner-Bratzler shear force (WBSF) and sarcomere length evaluations. All muscles except the SS had altered (P<0.05) sarcomere lengths between positions; the cranial position resulted in the longest sarcomeres for the SV and TB muscles whilst the natural position had longer sarcomeres for the PP and TM muscles. The SV from the cranial position had lower (P<0.05) shear than the caudal position and TB from the natural position had lower (P<0.05) shear than the parallel or caudal positions. Sarcomere length was moderately correlated (r=-0.63; P<0.01) to shear force.

Tenderization effect of soy sauce on beef M. biceps femoris

This study was conducted to evaluate the tenderization effect of soy sauce on beef M. biceps femoris (BF). Five marinades were prepared with 4% (w/v) sodium chloride and 25% (w/v) soy sauce solutions (4% salt concentration) and mixed with the ratios of 100:0 (S0, pH 6.52), 75:25 (S25, 5.40) 50:50 (S50, 5.24), 25:75 (S75, 5.05), and 0:100 (S100, 4.85), respectively. The BF samples which were obtained from Hanwoo cows at 48 h postmortem (n=24) were marinated with five marinades for 72 h at 4°C (1:4 w/w), and the effects of soy sauce on tenderness were evaluated. Soy sauce marination resulted in a decrease in the pH value of the BF sample. However, there were no significant differences in the water holding capacity (P<0.05). The S100 treatment showed the significant (P<0.05) increase in collagen solubility and myofibrillar fragmentation index, contributing to decreased shear force compared to S0 (control). Reduction in intensity of few myofibrillar protein bands were observed for S100 treatment compared to control using SDS-PAGE. Scanning electron microscopy revealed breakdown of connective tissue surrounding muscle fibers of the S100 treatment. The tenderization effect of soy sauce may attribute various mechanisms such as increased collagen solubility or proteolysis which depend on soy sauce level in marinade.

Effect of low- and high-forage diets on meat quality and fatty acid composition of Alentejana and Barrosã beef breeds

This study investigated the effects of genotype and diet on meat fat composition and palatability obtained from Alentejana (AL) and Barrosã (BA) breeds. Herein, 20 males from each breed allocated at 11 months of age were fed ad libitum a low-forage diet or a high-forage diet and slaughtered at 18 months of age. Trained sensory panel analysis found that the longissimus lumborum (Ll) muscle from BA had higher tenderness, juiciness and overall acceptability scores than the AL breed. The highest scores for those attributes were observed in the BA breed fed the high-forage diet. Regarding the semitendinosus (St) muscle, breed was a source of variation of tenderness scores. In contrast to the Ll muscle, the highest tenderness scores for the St muscle were observed in the AL breed. The intramuscular fat (IMF) content was positively correlated with tenderness, juiciness and overall acceptability in Ll muscle and negatively correlated with flavour in the St muscle. The levels of 14:0 and 16:0, 16:1c9, 18:1c9 and 18:1c11 were positively correlated to juiciness, tenderness and overall acceptability in the Ll muscle. These correlations were not observed in the St muscle, which may be related to its low IMF content. Nonetheless, negative correlations were observed for the St muscle between flavour and 14:0, 16:0 and 18:0 FA contents.The IMF varied widely in the Ll but not in the St muscle. The latter had higher levels of 16:1c9 and trans fatty acids (∑TFA) in the BA than in the AL breed. Regarding the Ll muscle, the BA had higher amounts of 14:0, 16:0, 16:1c9, 18:0, 18:1c9, 18:1c11, saturated fatty acids (∑SFA), cis monounsaturated fatty acids (∑cis MUFA), ∑TFA and n-3 polyunsaturated fatty acids (∑n-3 PUFA) than the AL breed. The diet exerted an influence on the IMF content and on the levels of 14:0, 16:0, 16:1c9, 18:0, 18:1c9, 18:1c11, ∑SFA, ∑cis MUFA and ∑TFA in both Ll and St muscles. Moreover, the levels of ∑n-3 PUFA in the Ll muscle and 18:2n-6, 20:4n-6, ∑n-6 PUFA and ∑PUFA in the St muscle were influenced by diet. The results obtained in this study, with two Portuguese breeds, confirm that genetic background plays a major role in the determination of meat eating quality.

Cluster analysis application identifies muscle characteristics of importance for beef tenderness

BACKGROUND

An important controversy in the relationship between beef tenderness and muscle characteristics including biochemical traits exists among meat researchers. The aim of this study is to explain variability in meat tenderness using muscle characteristics and biochemical traits available in the Integrated and Functional Biology of Beef (BIF-Beef) database. The BIF-Beef data warehouse contains characteristic measurements from animal, muscle, carcass, and meat quality derived from numerous experiments. We created three classes for tenderness (high, medium, and low) based on trained taste panel tenderness scores of all meat samples consumed (4,366 observations from 40 different experiments). For each tenderness class, the corresponding means for the mechanical characteristics, muscle fibre type, collagen content, and biochemical traits which may influence tenderness of the muscles were calculated.

RESULTS

Our results indicated that lower shear force values were associated with more tender meat. In addition, muscles in the highest tenderness cluster had the lowest total and insoluble collagen contents, the highest mitochondrial enzyme activity (isocitrate dehydrogenase), the highest proportion of slow oxidative muscle fibres, the lowest proportion of fast-glycolytic muscle fibres, and the lowest average muscle fibre cross-sectional area. Results were confirmed by correlation analyses, and differences between muscle types in terms of biochemical characteristics and tenderness score were evidenced by Principal Component Analysis (PCA). When the cluster analysis was repeated using only muscle samples from m. Longissimus thoracis (LT), the results were similar; only contrasting previous results by maintaining a relatively constant fibre-type composition between all three tenderness classes.

CONCLUSION

Our results show that increased meat tenderness is related to lower shear forces, lower insoluble collagen and total collagen content, lower cross-sectional area of fibres, and an overall fibre type composition displaying more oxidative fibres than glycolytic fibres.

Relationships between structural characteristics of bovine intramuscular connective tissue assessed by image analysis and collagen and proteoglycan content

Three muscles (Longissimus thoracis, Semimembranosus, Biceps femoris) of 40 young bulls from 3 breeds were used to quantify structural characteristics of bovine connective tissue by image analysis, with both macroscopic and microscopic approaches. Collagen and proteoglycan content was also investigated. Perimysium occupied a greater area (8 vs 6%), and was wider (42 vs 2 μm) and shorter per unit area (1.9 vs 30 mm mm(-2)) than endomysium. Perimysium and endomysium from Longissimus were thinner, less ramified than in Biceps. Longissimus showed less total collagen and cross-linking and more proteoglycans (P<0.0001) than Biceps muscle. Blond d'Aquitaine perimysium occupied less area, was more ramified and muscles contained less collagen, cross-linking and more proteoglycans than Angus (P<0.001). Limousin was intermediate. High proteoglycan content in muscle containing less total collagen suggested a complementarity between these molecules. They might influence mechanical properties of intramuscular connective tissue. This was especially true given that proteoglycans and total collagen were negatively and positively linked with structural parameters, respectively.

One technology does not fit all: profiling consumers of tender and tenderised beef steaks

New production technologies can help the beef sector to improve eating quality, in particular the tenderness, of low-value meat cuts. This paper aims at profiling potential consumers for unprocessed tenderloin M. Psoas major, muscle profiled M. Infraspinatus and marinated by injection M. Semitendinosus in Belgium (n=108) and Norway (n=110). Consumers' hedonic expectations for the three beef cuts, along with their general attitudes towards beef and food technology, were collected in central location tests. Results show that tenderloin triggers the highest hedonic expectations and best appeals to consumers profiled with high beef involvement in both countries. Consumers' expectations for steaks from novel technologies vary with consumers' attitudes towards beef, food technology and food risks and their country of residence, resulting in three additional consumer profiles. Furthermore, general attitudinal profiles of beef consumers also differ between the two countries. The results are useful for the positioning of novel beef products within the two national markets.

Chemical composition and cooking properties of beef forequarter muscles of Mexican cattle from different genotypes

Beef forequarter muscles biceps brachii (BRB), brachialis (BRA), complexus (COM), splenius (SPL), infraspinatus (INF), teres major (TER), rhomboideus (RHO), subscapularis (SUB), supraspinatus (SUP), triceps brachii long-head (TRB) and triceps brachii lateral-head (TRI) were obtained from Mexican beef carcasses originated from Bos indicus (Bi, n=10) or Bos taurus (Bt, n=10) young bulls. Muscles were analyzed for WBSF, cooking loss, and moisture and fat contents. INF had the lowest WBSF (37.23N) and cooking loss (31.78%) of all. RHO exhibited the lowest moisture (72.62%) and highest fat content (5.23%) of all. Bi genotype exhibited higher WBSF (53.78, 48.69N), higher cook loss (36.27, 34.32%), higher fat content (2.93, 2.35%), and lower moisture content (73.70, 75.07%) than Bt. Further research is needed to estimate the actual consumer acceptance of beef forequarter muscles and their marketing potential as individual cuts in the Mexican market.

Effect of sodium citrate plus sodium diacetate or buffered vinegar on quality attributes of enhanced beef top sirloins

As new pathogen intervention products come to market, it is important to ensure that they maintain or improve meat quality. Shelf-life and palatability traits were measured for top sirloins enhanced to 110% with solutions containing 0.5% sodium chloride and 0.4% sodium tripolyphosphate (CNT); CNT with a 1% solution of 80% sodium citrate plus 20% sodium diacetate (SC+D); or CNT with 2% buffered vinegar (VIN) in the final product. Enhancement solution did not influence color over 7days of retail display, except VIN was subjectively more red than CNT and SC+D on d 7 and SC+D had less discoloration than CNT on d 7 (P<0.05). VIN was rated lower (P<0.05) than CNT for trained sensory tenderness and there was no difference in shear force between treatments. SC+D and VIN show promise for use in beef enhancement solutions, however, further sensory studies are warranted.

Modification of muscle inherent properties through age at slaughter, growth promotants and breed crosses

Girard, I., Aalhus, J. L., Basarab, J. A., Larsen, I. L. and Bruce, H. L. 2011. Modification of muscle inherent properties through age at slaughter, growth promotants and breed crosses. Can. J. Anim. Sci. 91: 635–648. A 24 factorial experiment tested the interactions of slaughter age (12–13 or 18–20 mo), growth hormone use, β-adrenergic agonist (β-AA) use and breed cross [Hereford–Aberdeen Angus (HAA) or Charolais–Red Angus (CRA)] on the composition, fibre types, and connective tissue characteristics of m. semitendinosus (ST) and m. gluteus medius (GM) from 112 crossbred steers. Muscle weights increased with slaughter age, implantation and CRA genetics (P<0.05), but were not affected by ractopamine hydrochloride (RAC) (P>0.10).Animal age increased fast glycolytic (FG) and decreased fast oxidative glycolytic (FOG) fibre percentages by 7.2 and 6.6%, respectively, in the ST and increased slow oxidative (SO) and FOG fibre areas in both muscles (P<0.05). Cross-sectional areas of all fibre types were increased in the ST with implantation. In the GM, implantation increased SO (3.1%) and reduced FOG (3.2%) fibre percentages, while RAC reduced the SO (3.8%) and increased the FG (6.1%) fibre percentages (P<0.05).Only GM total collagen content increased with slaughter age (P<0.05),but collagen solubility decreased with slaughter age for both muscles (P<0.05). CRA genetics increased FG percentage in the GM of yearling-fed steers and increased moisture and protein and reduced fat contents of both muscles (P<0.05). In the muscles studied, IMP, slaughter age and animal genetics induced greater changes in muscle inherent properties than RAC.

Effects of manipulation of the caspase system on myofibrillar protein degradation in vitro

Apoptosis via the intrinsic caspase 9 pathway can be induced by oxidative stressors hydrogen peroxide (H₂O₂) and N-(4 hydroxyphenol) rentinamide (fenretinide), a synthetic retinoid. Accelerated muscle atrophy and proteolysis in muscle-wasting conditions have been linked to oxidative stress and activated protease systems. Therefore, the hypothesis of this study was that proteolysis of myofibrillar proteins could be manipulated through the induction or inhibition of the caspase system. After slaughter, LM and supraspinatus muscles from callipyge (n = 5) and normal (n = 3) lambs were excised, finely diced, and incubated with treatment buffers containing oxidative stressors fenretinide or H₂O₂, recombinant caspase 3, caspase-specific inhibitor N-acetyl-Asp-Glu-Val-Asp-CHO (DEVD), or control solution. Muscle samples were incubated for 1, 2, 7, and 21 d at 4°C. Activation of the initiator caspase, caspase 9, and myofibrillar protein degradation was determined by SDS-PAGE and Western blotting. Results showed that fenretinide, H₂O₂, and recombinant caspase 3 increased (P < 0.05) proteolysis of myofibril proteins, whereas DEVD inhibited degradation (P < 0.05). Proteolysis of myofibrillar proteins increased with incubation time (P < 0.0001), and incubation time × treatment interactions (P < 0.05) indicated that the treatment effects did not all occur at the same rate. This study has shown that manipulation of the caspase system through induction or inhibition of activity can affect degradation of myofibrillar proteins, providing further evidence that the caspase system could be involved in postmortem proteolysis and tenderization. However, these stimulated changes were not sufficient to overcome the lack of proteolysis that is characteristic of muscle from callipyge lambs.

Estimation of relationships between mineral concentration and fatty acid composition of longissimus muscle and beef palatability traits

The objective of this study was to determine the influence of beef LM nutrient components on beef palatability traits and evaluate the impact of USDA quality grade on beef palatability. Longissimus muscle samples from related Angus cattle (n = 1,737) were obtained and fabricated into steaks for trained sensory panel, Warner-Bratzler shear force (WBSF), lipid oxidation measured by thiobarbituric acid reactive substances (TBARS), fatty acid, and mineral composition analysis. Pearson phenotypic correlations were obtained by the correlation procedure of SAS. Beef palatability data were analyzed by the GLM procedure of SAS with USDA quality grade as the main effect. Specific mineral concentrations did not demonstrate strong correlations with WBSF or sensory traits (r = -0.14 to 0.16). However, minerals appeared to have a stronger relationship with flavor; all minerals evaluated except Ca and Mn were positively correlated (P < 0.05) with beef flavor. Stearic acid (C18:0), C18:2, C20:4, and PUFA were negatively correlated (P < 0.05) with all 3 panelist tenderness traits (r = -0.09 to -0.22) and were positively correlated (P < 0.05) with WBSF (r = 0.09 to 0.15). The MUFA were positively correlated (P < 0.05) with panelist tenderness ratings (r = 0.07 to 0.10) and negatively associated (P < 0.05) with WBSF (r = -0.11). The strongest correlations with juiciness were negative relationships (P < 0.05) with C18:2, C18:3, C20:4, and PUFA (r = -0.08 to -0.20). Correlations with beef flavor were weak, but the strongest was a positive relationship with MUFA (r = 0.13). Quality grade affected (P < 0.05) WBSF, TBARS, and all trained sensory panel traits, except livery/metallic flavor. As quality grade increased, steaks were more tender (P < 0.05), as evidenced by both WBSF and sensory panel tenderness ratings. Prime steaks were rated juiciest (P < 0.05) by panelists, whereas Select and Low Choice were similarly rated below Top Choice for sustained juiciness. Quality grade influenced (P < 0.05) beef flavor, but not in a linear fashion. Although there were significant correlations, these results indicate tenderness, juiciness, and flavor are not strongly influenced by individual nutrient components in beef LM. Furthermore, the positive linear relationships between USDA quality grade and beef palatability traits suggest quality grade is still one of the most valuable tools available to predict beef tenderness.

Effects of muscle type on beef taste-traits assessed by an electric sensing system

To assess the role of muscle fiber type in beef taste-traits, we analyzed cooked meats from bovine masseter, diaphragm, psoas major, longissimus thoracis, and semitendinosus muscles with an electric taste sensing system (INSENT SA402B). The system is composed of five taste sensors of polymer membranes fixing different lipids. The sensors, CT0, CA0, AAE, C00 and AE1 are designed to respond to the individual tastes of salty, sour, umami, bitter and astringent, respectively. The system found significant differences in the converted outputs of CA0 (cvCA0), C00 (cvC00) and AE1 (cvAE1) among the bovine muscles. The slow-type muscles (masseter and diaphragm) showed lower cvCA0, higher cvC00, and higher cvAE1 than did the fast-type muscles (psoas major, longissimus thoracis, and semitendinosus). Lactic acid content was different among muscle types and was highly related to the cvCA0 output and pH. carbonyl compounds and free fatty acids were higher in the slow-type muscles. Free fatty acids were major components causing the difference in the C00 output among the muscle types. Iron content was also different among the muscle types and related to the cvC00 and cvAE1 outputs. These results suggested that the muscle fiber type affects the beef taste characteristics.

Kinetic analysis of cooking losses from beef and other animal muscles heated in a water bath--effect of sample dimensions and prior freezing and ageing

Cooking loss kinetics were measured on cubes and parallelepipeds of beef Semimembranosus muscle ranging from 1 cm × 1 cm × 1 cm to 7 cm × 7 cm × 28 cm in size. The samples were water bath-heated at three different temperatures, i.e. 50°C, 70°C and 90°C, and for five different times. Temperatures were simulated to help interpret the results. Pre-freezing the sample, difference in ageing time, and in muscle fiber orientation had little influence on cooking losses. At longer treatment times, the effects of sample size disappeared and cooking losses depended only on the temperature. A selection of the tests was repeated on four other beef muscles and on veal, horse and lamb Semimembranosus muscle. Kinetics followed similar curves in all cases but resulted in different final water contents. The shape of the kinetics curves suggests first-order kinetics.

Perception in France of the Australian system for the prediction of beef quality (Meat Standards Australia) with perspectives for the European beef sector

Australia has developed the Meat Standards Australia (MSA) grading scheme to predict beef quality for consumers. This system is comprehensive, accurate and scientifically supported. It is based on the development and the use of a research database with a large amount of data, including the use of a large-scale consumer testing system with cuts cooked in different ways as well as information on the corresponding animals, carcasses and cuts. The system is also based on statistical analyses carried out on this database to identify the critical control points of beef palatability which is indicated for individual muscles and for a specific cooking method and aging time. Experts involved in the French beef industry were questioned about their knowledge and views on the application of the MSA system. They recognised many qualities of the MSA system and it was judged as original, relevant and sufficiently mature in its application, and favouring scientifically based prediction of beef quality rather than replying on tradition and perceptions of quality. It was also thought to be credible, flexible and open ended. However, it was still considered to possess some weak points. Thus, while its development in Australia at the farmer and abattoir level has been impressive in a relatively short time, the final delivery of precise quality grades to consumers is still lacking at retail due to only partial implementation of the system. Its adaptability to France would be difficult due to the complexity of the French beef industry and market. But, the program is uniquely innovative and deserves consideration. It will facilitate awareness and induce much needed changes to underpin the preservation and the development of the beef sector in France and eventually in Europe.

Effect of age and cut on cooking loss, juiciness and flavour of South African beef

The juiciness and flavour characteristics of 15 aged primal beef cuts of electrically stimulated carcasses, from three different age groups, were assessed (n=61). Cooking losses were determined and proximate analyses (moisture, fat, nitrogen and ash) were performed. Tender cuts were cooked by a dry heat method, and less tender cuts were cooked by moist heat methods. A trained panel (n=10) evaluated sensory quality characteristics including initial and sustained juiciness, aroma and flavour. Flavour intensity was the biggest discriminant between the three age groups and declined with an increase in age. Initial impression of juiciness decreased with increased age of the animal and cooking losses increased nonlinearly with age, irrespective of the muscle. In contrast sustained juiciness increased with increased age. Cuts cooked according to a dry heat cooking method were reported juicier (both initial and sustained) than those cooked by moist heat methods.

Application of exogenous enzymes to beef muscle of high and low-connective tissue

Exogenous enzymes tenderize meat through proteolysis. Triceps brachii and Supraspinatus were randomly assigned to the seven enzyme treatments, papain, ficin, bromelain, homogenized fresh ginger, Bacillus subtilis protease, and two Aspergillus oryzae proteases or control to determine the extent of tenderization (Warner-Bratzler shear and sensory evaluation) and mode of action (myofibrillar or collagen degradation). Sensory evaluation showed improvement (P<0.0009) for tenderness and connective tissue component and all except ginger had a lower shear force than the control (P<0.003). Ginger produced more off-flavor than all other treatments (P<0.0001). Only papain increased soluble collagen (P<0.0001). Control samples were only significantly less than ficin for water soluble (P=0.0002) and A. oryzae concentrate for salt soluble proteins (P=0.0148). All enzyme treatments can increase tenderness via myofibrillar and collagenous protein degradation with no difference among high and low-connective tissue muscles.

Assessment of the sensory quality and shelf stability of selected Horro beef muscles in Ethiopia

The objective of this work was to assess sensory quality and retail life of Horro beef muscles in Ethiopia. Six muscles: M. rhomboideus (RM), M. infraspinatus (IS), M. longissimus lumborum (LL), M. semimembranosus (SM), M. biceps femoris (BF) and M. rectus femoris (RF) were considered. Sensory quality of the muscles was rated by a 9-member trained panel for palatability, tenderness, juiciness, amount of connective tissue (ACT), lean color and surface discoloration and measured by Warner-Bratzler Shear Force (WBSF). Retail life of the six muscles were evaluated for CIE 1976 L(∗)a(∗)b(∗) color values across 6 days. Significant differences (p<0.05) between muscles for all sensory attributes and WBSF were found. Significant L(∗)a(∗)b(∗) color values of muscles and USDA quality grades by retail life were found (p<0.05). Significant correlations (p<0.05 or p<0.01) of key parameters were also identified.

Effects of supplementing feedlot steers and heifers with zilpaterol hydrochloride on Warner-Bratzler shear force interrelationships of steer and heifer longissimus lumborum and heifer triceps brachii and gluteus medius muscles aged for 7, 14 and 21d

Longissimus lumborum (LL) muscles from 117 steers plus LL, gluteus medius (GM), and triceps brachii (TB) muscles from 132 heifers were evaluated for effects of feeding duration of zilpaterol hydrochloride (Zilmax(R); ZH; 7.56g/907kg on a dry matter basis) and aging time on tenderness. Both genders were blocked by initial weight into six blocks of four pens. Pens were assigned to treatments of control (C), or 20, 30 or 40days on ZH, with a 3day withdrawal. Steaks from each subprimal were vacuum aged individually for 7, 14 or 21days, frozen, thawed, and cooked to 71 degrees C for Warner-Bratzler shear force (WBSF). All muscles from steers and heifers from ZH30 and ZH40 treatments had higher (P<0.05) WBSF than those of C. The WBSF of steer LL and heifer TB from the ZH20 treatment was higher (P<0.05) than C. There was a treatment by aging interaction (P>0.05) for WBSF of GM steaks from heifers. Percentage of intramuscular fat had little effect on tenderness. Percentages of steer LL and heifer TB steaks with WBSF values below thresholds of either 5.0 or 4.6kg from the ZH20 treatment were quite high, whereas percentages of heifer LL and GM muscles below 5.0kg (67%) and 4.6kg (57%) were low. Feeding ZH20days generally increased WBSF values, but mean WBSF values for steer LL and heifer TB were below 4.6kg. Feeding ZH 20days resulted in>40% of GM steaks with WBSF values above 4.6kg.