Longissimus Steaks Research Articles

The effect of retail packaging method on objective and consumer assessment of beef quality traits

This study evaluated the effect of 7days of modified atmosphere packaging (MAP: 80% O2, 20% CO2) or skin packaging (no oxygen) of beef M. longissimus steaks after 1 or 7days of ageing in vacuum on objective and sensory meat quality traits and degradation of desmin. Shear force was negatively affected by MAP after both 1 and 7days of ageing in vacuum (P<0.005). Sensory evaluation of grilled steaks revealed significantly negative effects of MAP on sensory traits, resulting in an overall decrease of 8 points in the Meat Standards Australia (MSA) eating quality score (MQ4). Desmin degradation was not affected by packaging method, suggesting that the toughening effect of high-oxygen MAP is not due to inhibition of postmortem proteolysis. The results of this study and others suggest that packaging method should be incorporated as a variable in the MSA grading system. Further research to quantify the impact of oxidative cross-linking of proteins on tenderness appears warranted.

Effect of ractopamine hydrochloride and zilpaterol hydrochloride on tenderness of Longissimus steaks of Bos taurus steers

Effect of ractopamine hydrochloride and zilpaterol hydrochloride on tenderness of Longissimus steaks of Bos taurus steers

Myofibril Fragmentation Index as an Immediate Postmortem Predictor of Buffalo Meat Tenderness

A study was undertaken to compare and correlate the myofibril fragmentation index (MFI) of fresh buffalo longissimus steaks with Warner-Bratzler shear force (WBSF) and the subjective measurement of overall tenderness to suggest the suitability of MFI as a predictor of cooked buffalo meat tenderness. The study revealed a significant positive correlation (P < 0.01) between MFI and WBSF from day 1 to 8. The mean correlation coefficients (r2) of overall tenderness with MFI and WBSF were 0.61 and 0.73, respectively. This indicates that MFI could be used as an objective method of evaluation of tenderness of buffalo meat as it is strongly correlated with the overall tenderness and WBSF. Therefore, MFI of raw aged buffalo longissimus steaks can be used as a predictor of cooked buffalo meat tenderness enabling selection of tender meat for retail sale and processing. Furthermore, the results imply that significant tenderization occurs during the first 24 h postmortem. Practical Applications Myofibril fragmentation index appears to be an effective tool in predicting meat tenderness early postmortem as it was found to correlate with both Warner-Bratzler shear force values and objective measures of tenderness of cooked meat. This index is a very useful indicator of meat tenderness, particularly for muscles not big enough to determine shear force or sensory tenderness. This can be of special promise to the meat industry or retailers in developing countries where there is a need for early postmortem measurements to assess meat quality as early as possible after slaughter. A significant amount of tenderization occurs during the first 24 h postmortem as is obvious from the results; the industry can equip themselves to further enhance this early postmortem proteolysis so that the consumer acceptance of the final product can be improved.

2013 EARLY CAREER ACHIEVEMENT AWARD— Proteomics of muscle- and species-specificity in meat color stability12

Meat color is the most important quality trait influencing consumer purchase decisions. The interinfluential interactions between myoglobin and biomolecules govern color stability in meat. The advances in proteomics, such as high throughput analytical tools in mass spectrometry, 2-dimensional electrophoresis, and bioinformatics, offer themselves as robust techniques to characterize the proteome basis of muscle- and species-specific meat color phenomena. Differential abundance of chaperones and antioxidant proteins contributes to muscle-specific color stability in beef; the greater abundance of chaperones and antioxidant proteins in color-stable Longissimus lumborum than in color-labile Psoas major protects myoglobin and contributes to superior color stability of beef Longissimus steaks. Lipid oxidation-induced myoglobin oxidation is more critical to beef color than pork color due to the inherent differences in myoglobin chemistry; the number of nucleophilic histidine residues adducted by reactive aldehydes is greater in beef myoglobin than in pork myoglobin. Preferential adduction of secondary products of lipid oxidation to beef myoglobin accelerates metmyoglobin formation at a greater degree than in its pork counterpart. Mass spectrometric investigations revealed that although cherry-red carboxymyoglobin is more stable than oxymyoglobin, both redox forms undergo lipid oxidation-induced oxidation in model systems. The accuracy of mass spectrometry to detect the molecular mass of proteins has been applied to differentiate myoglobins from closely related meat animals, such as goats and sheep or emu and ostrich. In addition, this approach indicated that turkey myoglobin is 350 Da greater in molecular mass than beef myoglobin, and the unique biochemistry of turkey myoglobin could be responsible for its greater thermostability in model systems as well as the pink color defect observed in fully cooked uncured turkey products.

Effects of blade tenderization, aging method and aging time on meat quality characteristics of Longissimus lumborum steaks from cull Holstein cows

The effects of blade tenderization (BT), two aging methods (dry (D) and wet (W)), and aging time (2 and 23 d) on tenderness, color, and sensory properties of Longissimus lumborum muscles from 12 cull Holstein cows were evaluated. Dry-aged loins had higher combined trim and aging losses than control (C) for both D- and W-aging, mostly because of excess trim losses. BT steaks had WBSF of 33.13N while C steaks had WBSF of 41.46N (P=0.09). Aging decreased WBSF. Blade tenderized steaks had higher cook loss than C steaks. Aging, W-aging, and BT×W-aging improved myofibrillar (sensory) tenderness scores. Aging and/or BT improves sensory panel tenderness cull cow Longissimus lumborum steaks. Aging and blade tenderization combined can increase tenderness and value of Longissimus steaks from cull Holstein cows.

Prediction of troponin-T degradation using color image texture features in 10 d aged beef longissimus steaks

The objective was to use digital color image texture features to predict troponin-T degradation in beef. Image texture features, including 88 gray level co-occurrence texture features, 81 two-dimension fast Fourier transformation texture features, and 48 Gabor wavelet filter texture features, were extracted from color images of beef strip steaks (longissimus dorsi, n=102) aged for 10d obtained using a digital camera and additional lighting. Steaks were designated degraded or not-degraded based on troponin-T degradation determined on d 3 and d 10 postmortem by immunoblotting. Statistical analysis (STEPWISE regression model) and artificial neural network (support vector machine model, SVM) methods were designed to classify protein degradation. The d 3 and d 10 STEPWISE models were 94% and 86% accurate, respectively, while the d 3 and d 10 SVM models were 63% and 71%, respectively, in predicting protein degradation in aged meat. STEPWISE and SVM models based on image texture features show potential to predict troponin-T degradation in meat.

Effects of feeding a single or sequence of beta-adrenergic agonists on cull cow meat quality

Sixty cull cows were implanted and assigned to four treatments: C = concentrate ration only; RH = supplemented with ractopmaine-HCl (8.33mg/kg of feed) for 25d; ZH = supplemented with zilpaterol-HCl (ZH) (200mg head –1d–1) for the last 20d; and RH+ZH = supplemented with RH for 25d followed by ZH for 20d. All cows were fed a concentrate ration for 74d. Infraspinatus steaks from cows supplemented with RH and/or ZH had lower (P<0.05) shear force than steaks from C cows. Longissimus (LM) steaks from the 6–8th rib section of ZH and RH+ZH cows had decreased (P<0.0001) desmin degradation at 10 and 21d postmortem compared to steaks from C and RH cows. Collagen solubility of the LM was increased (P<0.05) by ZH and RH+ZH compared to C. There were no treatment differences in 12th rib LM tenderness when enhanced with calcium lactate. Color and sensory traits of meat from RH+ZH cows were not different from C but flavor intensity was greater and off-flavor less than for C cows.

Feeding performance, carcass characteristics, and tenderness attributes of steers sorted by the Igenity tenderness panel and fed zilpaterol hydrochloride

Steers (n = 560; initial BW = 420 ± 26 kg) were selected from a pool of 1,040, using the IGENITY Profile DNA test for tenderness, sorted into 1 of 4 tenderness genotype (TG) groups [140 tough (TUF), 140 intermediate (INT), 140 tender (TEND), or 140 mixed (MXD)], and subsequently allocated into 56 pens at random, of which one-half (28 pens, 7 pens from each TG) were supplemented the β-adrenergic agonist zilpaterol hydrochloride (ZH) and the balance fed a control ration. No TG × ZH interaction (P ≥ 0.15) occurred for any measured trait. Cattle from INT TG had less (P < 0.05) DMI during pretreatment (d 0 to 118) and entire trial (d 0 to 143) periods than other TG. Cattle fed ZH had greater (P < 0.01) ADG and G:F, and decreased (P < 0.01) DMI during the treatment period (d 119 to 143). Cattle from the TEND group had greater (P < 0.01) marbling scores, increased (P < 0.02) calculated USDA yield grades (YG), and more (P < 0.02) calculated empty body fat (EBF) than TUF cattle. Cattle receiving ZH during the treatment period had increased (P < 0.01) HCW, dressed yield, and LM area. Additionally, cattle fed ZH exhibited decreased (P < 0.01) EBF, marbling, KPH, and calculated USDA YG. No difference (P > 0.06) in YG distributions were detected among TG, yet TEND cattle were represented by a greater (P < 0.01) proportion of Prime and premium Choice carcasses. Cattle fed ZH exhibited increased (P < 0.01) frequencies of YG 2 carcasses and fewer (P < 0.01) YG 3, 4, and 5 carcasses concurrent with an increase (P < 0.04) in the percentage of Select carcasses. Longissimus steaks from TUF cattle had greater (P < 0.03) Warner-Bratzler Shear Force (WBSF) values at 7 and 14 d postmortem than steaks from INT or TEND cattle. Furthermore, ZH-fed cattle had increased (P < 0.01) WBSF values for all aging periods compared with control cattle. Frequency of steaks with WBSF values <3.9 kg (certified tender) were less (P < 0.05) for the TUF group. Feeding ZH resulted in fewer longissimus steaks (P < 0.01) with WBSF values <3.0 kg (guaranteed tender) across all aging periods; however, no difference in the frequency of steaks with WBSF values <3.9 kg was found after 21 d of aging. Igenity Profile tenderness scores were correlated (P < 0.05) to carcass finish attributes and WBSF values. Commercially available tenderness panels may have the potential to allow for antemortem sorting of cattle into expected tenderness groupings, which could augment feeding management strategies and ultimately lead to increased marketing value for the beef system.

Relationship between residual feed intake and end product palatability in longissimus steaks from steers sired by Angus bulls divergent for intramuscular fat expected progeny difference

ABSTRACT The relationship between residual feed intake (RFI) and end product quality was evaluated in 133 steers from 5 Angus sires with low, moderate, or high percent intramuscular fat EPD. Steers (320.1 ± 35.76 kg) were evaluated for RFI during a 70- to 84-d growing period and classified into 3 groups based on RFI: efficient (less than -0.5 SD below the mean; n = 41), marginal (± 0.5 SD from the mean; n = 48), and inefficient (> 0.5 SD above the mean; n = 44). There were no differences among RFI groups for ADG, BW, fat thickness, carcass weight, YG, QG, or palatability traits. Inefficient steers had greater (P

Cookery method and end-point temperature can affect the Warner–Bratzler shear force, cooking loss, and internal cooked color of beef longissimus steaks

Steaks from 60 beef ribeye rolls were used to test the interactive effects of cookery method and end-point temperature on Warner–Bratzler shear force (WBSF) and internal cooked color. Pairs of longissimus thoracis (LT) steaks were assigned to combinations of 3 different end-point temperatures and 5 cookery methods. The forced-air convection oven (FAC) required the longest time and produced the reddest internal color, regardless of end-point temperature. The clam–shell grill (CLAM) required the least cooking time and resulted in the lowest cooking losses, but CLAM-cooked steaks also had the greatest WBSF values and least red internal color. Repeatability values for WBSF were acceptable (> 0.60) for all degrees of doneness when steaks were cooked in the FAC and impingement oven, but steaks cooked on the CLAM were not repeatable. The relationship of myofibrillar toughening, moisture loss and cooked color changes in beef LT steaks also differed due to cookery methods.

Effect of time of measurement on the relationship between metmyoglobin reducing activity and oxygen consumption to instrumental measures of beef longissimus color stability

Contributions of initial and retained levels of oxygen consumption and reducing capacity to animal variation in color stability were evaluated. Instrumental color values were determined on longissimus steaks (n = 257) during 6 d of display. Oxygen consumption (OC), nitric oxide metmyoglobin reduction (NORA), initial metmyoglobin formation (IMF), and post-reduction metmyoglobin (PRM) were measured on d 0 and 6. During display, color variables, OC and reducing ability decreased ( P < 0.05). Color stable steaks had greater ( P < 0.05) reducing ability on d 0 and 6 and lower ( P < 0.05) OC on d 0 than unstable steaks. Color change was correlated to OC, NORA, and PRM on d 0 (r = 0.19, − 0.44 and 0.45, respectively) and to NORA and PRM on d 6 (r = − 0.50 and 0.52, respectively). These data suggest that initial capacity for OC and reducing ability, combined with retained reducing ability contribute to animal variation in color stability.

Effects of lactate-enhancement on surface reflectance and absorbance properties of beef longissimus steaks

A completely randomized block design was used to assess the effects of lactate-enhancement on surface reflectance and absorbance properties of beef longissimus steaks. Loins were divided into sections, assigned to one of four treatments (non-enhanced day 0, non-enhanced day 5, water-enhanced, and 3% lactate), vacuum packaged, stored for 5 days at 4 °C, and then cut into steaks that were used to prepare 100% of deoxy-, oxy-, met-, and carboxymyoglobin according to AMSA (1991). Surface color was analyzed using a HunterLab Miniscan Plus Spectrocolorimeter. Lactate-enhanced steaks had the least overall surface reflectance and the darkest surface color (lower L*; P < 0.05). For 100% of each myoglobin form, K/ S values and ratios (isobestic wavelengths ÷ 525 nm) at 474, 525, 572, and 610 also were influenced by lactate-enhancement. Hence, when estimating surface myoglobin forms using K/ S ratios, separate 100% myoglobin reference standards should be prepared from both non-enhanced and enhanced steaks.

Aging improves tenderness of longissimus muscle steaks from fed mature cows (2009)

Steaks from cows are tougher than those from young steers and heifers. This difference is often attributed to the increased cross-linkage of collagen in muscle of mature animals that is considered very stable and more resistant to postmortem degradation. Aging steaks from young steers and heifers is a common postmortem practice used to improve tenderness of steaks from the ribeye roll and strip loin. Improvement in tenderness because of aging has been attributed to enzymatic degradation of, primarily, the myofibrillar fraction of muscle and is most beneficial for low connective tissue muscles. Because muscles from mature cows have more collagen cross-linking, postmortem tenderization methods, such as blade tenderization and enzymatic tenderization, are often used to increase tenderness of steaks from mature cows. However, few studies have investigated the effect of aging on tenderness of longissimus muscle steaks from fed mature cows. Therefore, the objective of this study was to determine effects of aging on tenderness of longissimus steaks of fed mature cows from different management strategies.

Influence of Angus and Belgian Blue bulls mated to Hereford × Brahman cows on growth, carcass traits, and longissimus steak shear force1,2

Steers and heifers were generated from Angus (A) and Belgian Blue (BB) sires mated to Brahman x Hereford (B x H) F(1) cows to characterize their growth, carcass traits, and LM shear force. A total of 120 B x H cows purchased from 2 herds and 35 bulls (14 A and 21 BB) produced calves during the 5-yr project. After the stocker phase, a representative sample of A- and BB-sired heifers and steers were transported to the Iberia Research Station to be fed a high-concentrate diet. The remaining cattle were transported to a commercial feedlot facility. Each pen of cattle from the commercial feedlot was slaughtered when it was estimated that heifers and steers had 10 mm of fat or greater. The BB-sired calves were heavier at birth (P < 0.01) than the A-sired calves. During the feedlot phase, the A-sired calves gained more BW (P < 0.05) than the BB-sired calves. The BB-sired calves had heavier (P < 0.01) carcass weights than the A-sired calves. This was due to a combination of a heavier final BW and greater dressing percent. Because of their greater muscling and reduced (P < 0.01) fat, carcasses from BB-sired calves had greater yield (P < 0.01) compared with carcasses from A-sired calves. Carcasses from A-sired calves had a greater (P < 0.01) marbling score and greater (P < 0.01) USDA quality grade than carcasses from BB-sired calves. Tenderness, as measured by shear force of the steaks aged for 7 d, was similar for A- and BB-sired calves. However, steaks aged for 14 d from the A-sired calves had a reduced shear force (P < 0.01) compared with steaks from the BB-sired calves. Steer calves were heavier (P < 0.01) at birth and weaning, and had more total BW gain in the feedlot, which resulted in a heavier final BW and HCW compared with the heifers. Steer carcasses also had greater marbling scores and quality grades, whereas the heifer carcasses had larger LM area per 100 kg of carcass weight. In conclusion, the BB-sired calves had heavier carcass weights and greater cutability, whereas the A-sired calves had a greater degree of marbling and greater quality grade, and steaks from carcasses of A-sired calves were more tender as measured by shear force at 14 d.

Effects of data expression, sample location, and oxygen partial pressure on initial nitric oxide metmyoglobin formation and metmyoglobin-reducing-activity measurement in beef muscle

Methodology for measuring surface and subsurface metmyoglobin-reducing activity (MRA) of beef longissimus lumborum, semimembranosus, and psoas major was evaluated by submerging samples from the upper one half of 2.54 cm thick steaks in 0.3% NO 2 - , vacuum packaging, and incubating at 30 °C for 2 h to promote pigment reduction. Initial metmyoglobin formation (IMF) and post-reduction metmyoglobin (PRM) were measured and used to calculate relative and absolute MRA values. The subsurface of all muscles maintained more ( P < 0.05) reducing capacity after 6 d of display than the surface. Subsurface MRA was not significantly ( P > 0.05) correlated with surface colour stability whereas IMF was most correlated with colour stability (| r| > 0.77; P < 0.05). Longissimus steaks packaged in 20% O 2 had more ( P < 0.05) surface MRA than steaks packaged in 80% O 2 although measurement of MRA for steaks packaged in high-oxygen with this methodology is questioned. Determination of IMF is a better indicator of MRA for steaks exposed to atmospheric O 2 than more traditional measurements based on the amount of pigment reduced over time.

The relationship of physiological maturity and marbling judged according to Korean grading system to meat quality traits of Hanwoo beef females

Fifty seven carcasses from Hanwoo beef females were randomly selected by official meat graders and were sorted into three levels of maturity and marbling. Carcass data was collected for back fat thickness, longissimus area, carcass weight, meat colour, fat colour, marbling score, yield and quality grades. Mature carcasses had more yellow fat, coarser texture, a larger longissimus muscle area and lower quality grades and marbling scores ( P < 0.05). Carcasses with a higher marbling score had thicker fat and a higher quality grade. Carcasses with low marbling had a higher yield grade and a coarser texture ( P < 0.05). Higher marbling scores corresponded with lower cook and drip loss values for longissimus steaks. As the maturity of carcass was increased, the redness and lightness of meat and the yellowness of fat all tended to increase. Tenderness, flavour and overall acceptability scores for the older maturity group were lower than for younger and intermediate groups. Marbling was significantly ( P < 0.01) correlated with quality grade, crude fat content, cook and drip losses, and Warner–Bratzler shear force. The maturity level was also significantly ( P < 0.01) correlated with quality grade, fat colour, texture score, number of calves produced and milk teeth, meat redness and yellowness, fat yellowness, and Warner–Bratzler shear force. Results indicate that a low marbling group and older maturity group based on Korean grading system could negatively influence carcass traits and beef qualities of Hanwoo beef female.

Effects of low-voltage electrical stimulation and rapid chilling on meat quality characteristics of Chinese Yellow crossbred bulls

In this study, the effects of low-voltage electrical stimulation (LVES) and rapid chilling (RC) treatments on the quality characteristics of beef carcasses were evaluated, including the rate of pH and temperature decline, evaporative loss of carcasses, purge loss, cooking loss, and shear force values of m. longissimus steaks. Each carcass of 28 Chinese Yellow crossbred (Simmental × Yanbian) bulls was subjected to one of the four treatments, i.e., electrical stimulation and conventional chilling (ES/NR), electrical stimulation and rapid chilling (ES/RC), no electrical stimulation and rapid chilling (NE/RC), or no electrical stimulation and conventional chilling (NE/NR). Carcass pH and temperature were measured at 1, 3, 5, 7, 9, 11, and 24 h post-mortem. After that, a 2.5-cm-thick m. longissimus steak was taken from the right side of each carcass and used for analyses of purge loss, cooking loss and Warner–Bratzler shear force (WBSF). The results showed that LVES accelerated the rate of carcass pH decline ( P < 0.05) and rapid chilling increased the rate of carcass temperature decline ( P < 0.05). There was no significant difference found for the mean carcass evaporative losses from all treatments ( P > 0.05). Mean purge losses for m. longissimus steaks from rapidly chilled carcasses were lower ( P < 0.05) than those from conventionally chilled carcasses. Electrical stimulation had no impact on m. longissimus steak purge losses ( P > 0.05). Rapid chilling significantly decreased ( P < 0.05) the cooking loss of m. longissimus steaks from electrically stimulated carcasses whilst it increased the cooking loss of m. longissimus steaks from carcasses without stimulation ( P < 0.05). LVES increased ( P < 0.05) cooking loss of m. longissimus steaks from conventionally chilled carcasses, but had no effect under the procedure of pre-rigor rapid chilling ( P > 0.05). The lowest mean shear force value was found for the ES/NR-treated m. longissimus steaks, whilst the highest one for the NE/RC-treated carcasses ( P < 0.05). Regression analyses indicated that carcass pH at 1 h post-mortem was the most useful predictor for beef shear force. Abattoirs processing Chinese Yellow bulls could optimize meat quality by using low-voltage stimulation together with pre-rigor rapid chilling.

On-line classification of US Select beef carcasses for longissimus tenderness using visible and near-infrared reflectance spectroscopy

The current experiment was conducted to evaluate the on-line application of visible and near-infrared spectroscopy (VISNIR) to US Select carcasses during commercial beef carcass grading procedures to predict tenderness of longissimus steaks after 14 days of refrigerated storage. A regression model was calibrated using 146 carcasses and tested against an additional 146 carcasses. Carcasses were segregated into VISNIR-based tenderness classes based on whether their VISNIR-predicted slice shear force value was less than (tender) or greater than (tough) the median predicted slice shear force value. Carcasses classified as tender by VISNIR had a lower mean SSF value, were less likely to have slice shear force values greater than 245 N, had higher trained sensory panel tenderness ratings, and were less likely to have trained sensory panel tenderness ratings below slightly tender than were carcasses classified as tough (P<0.001). This technology might be useful for identification of US Select carcasses that excel in longissimus tenderness.

Heritability and correlation estimates of Warner-Bratzler shear force and marbling score from Angus-, Charolais-, Hereford-, and Simmental-sired cattle (2003)

The objective of this study was to estimate heritabilities and genetic correlations for Warner- Bratzler shear force and marbling score of longissimus steaks from Angus-, Charolais-, Hereford-, and Simmental-sired cattle in the National Cattlemen's Beef Association (NCBA) coordinated Carcass Merit Traits Project funded with Beef Checkoff dollars. There were 700 Angus-sired steers, 691 Charolais-sired steers and heifers, 938 Hereford-sired steers, and 1,167 Simmental-sired steers and heifers in the study. Restricted maximum likelihood estimates of the genetic parameters were determined using a sire model with a sire/maternal grandsire relationship matrix. The heritabilities for Warner-Bratzler shear force and marbling score, respectively, were 0.35 and 0.36 for Angus, 0.43 and 0.26 for Charolais, 0.12 and 0.59 for Hereford, and 0.13 and 0.42 for Simmental. The genetic and phenotypic correlations between Warner-Bratzler shear force and marbling score, respectively, were -0.19 and -0.18 for Angus; -0.36 and -0.19 for Charolais; - 0.47 and -0.23 for Hereford; and +0.64 and - 0.11 for Simmental. The high positive genetic correlation between Warner-Bratlzer shear force and marbling score for Simmental sires indicates that as marbling increased Warner- Bratzler shear force increased (decreased tenderness). These results suggest that selection for increased marbling in the Simmental breed would actually have a detrimental effect on tenderness. Selection for Warner-Bratzler hear force in Angus and Charolais could result in improved in tenderness, but little progress would be expected in Hereford sired cattle. In general, selection for marbling score in these breeds would improve tenderness only minimally.

Effects of supplemental vitamin D3 on feed intake, carcass characteristics, tenderness, and muscle properties of beef steers.

Research was conducted to determine the effects of supplemental dietary vitamin D3 on DMI, carcass traits, Warner Bratzler shear (WBS) force, calpastatin activity, plasma minerals, pH (0, 3, 12, and 24 h after slaughter), water-holding capacity (WHC), and sensory characteristics of three muscles. Pre-slaughter vitamin D3 treatments included no supplemental vitamin D3, 6 x 106 IU (MIU) of vitamin D3 for 4 d, or 6 MIU of vitamin D3 for 6 d. Cattle were slaughtered and carcasses were chilled for 48 h before removal of steaks from the longissimus, gluteus medius, and biceps femoris muscles. Steaks were aged at 2 degrees C for 7, 14, or 21 d before cooking to a final internal temperature of 70 degrees C for WBS and sensory panel analysis. Dry matter intake was lower for steers supplemented with vitamin D3 for 4 or 6 d. Live and carcass weights were lower (P < 0.05) in steers supplemented with vitamin D3. Supplementing 6 MIU/6 d of vitamin D3 decreased (P < 0.05) WBS values of gluteus steaks (pooled over aging times). Longissimus steaks from steers supplemented with vitamin D3 for 6 d had lower (P < 0.05) WBS force values than these steaks from control steers or steers fed vitamin D3 for 4 d at 7 d postmortem. Biceps femoris steaks from steers receiving vitamin D3 for 4 d had higher WBS values than steaks from control steers at 14 and 21 d postmortem. Feeding vitamin D3 at 6 MIU for 6 d decreased (P < 0.05) the percentage of steaks that had WBS values > or = 3.86 kg for all steaks. Feeding vitamin D3 had no effect on palatability traits evaluated by trained panelists. Blood Ca concentrations were greater (P < 0.05) when vitamin D3 was fed and with increased vitamin D3 feeding time. Feeding vitamin D3 for 6 d (vs 4 d) delayed pH decline for all muscle types after 0, 3, and 12 h postmortem. Water-holding capacity was increased (P > 0.02) after 0 h, 24 h, and 21 d postmortem when vitamin D3 was fed and was greater at 0 and 24 h if vitamin D3 was fed for 6 d rather than 4 d. These data suggest that supplementing 6 MIU of vitamin D3 will decrease DMI and improve beef tenderness through increased blood plasma Ca concentrations and WHC.