J. Anim Sci. 2007. 85:754-768. doi:10.2527/jas.2006-294
© 2007 American Society of Animal Science
Tasco supplementation: Effects on carcass characteristics, sensory attributes, and retail display shelf-life1
K. W. Braden*,2,
J. R. Blanton, Jr.*,
J. L. Montgomery
,
E. van Santen
,
V. G. Allen
and
M. F. Miller*,3
* Department of Animal and Food Sciences, Texas Tech University, Lubbock 79409-2162;
and
Department of Plant and Soil Sciences, Texas Tech University, Lubbock 79409-2122;
and
Department of Agronomy and Soils, Auburn University, Auburn, AL 36849-5412; and
and
Intervet Inc., Millsboro, DE 19966
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Abstract
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Two hundred crossbred cattle (Bos indicus x Bos taurus) were supplemented with 2% Tasco (Ascophyllum nodosum) in a commercial finishing facility to evaluate marbling score, USDA quality grade, sensory traits, and retail display shelf life. Treatment animals (n = 100) received a steam-rolled corn (Zea mays)-based diet containing 2% Tasco meal (DM basis), for 14 d beginning at d 45 of the finishing period and again 14 d before slaughter. Control animals (n = 100) received a steam-rolled corn (Zea mays)-based diet without Tasco at identical feeding periods. Carcasses from Tasco-fed cattle exhibited greater marbling scores (P = 0.003) than controls. There were no treatment effects (P > 0.05) on sensory, shear, or purge attributes of striploin or inside round steaks with the exception of inside round steaks from Tasco animals having a greater initial tenderness (P = 0.03) and lower off-flavor score (P = 0.002) than control steaks. The LM samples from Tasco-fed cattle had a greater percentage of ether extractable fat (P = 0.001) and lower percentage of protein (P = 0.001) than controls. Inside round samples from treated animals exhibited a greater percentage of moisture (P = 0.03) than control steaks. Visual lean color of striploin steaks was not affected by Tasco supplementation (P = 0.26); however, steaks from Tasco-treated animals were more uniform and had less discoloration and browning than those from controls (P = 0.005, 0.04, and 0.05, respectively). Inside round visual scores and instrument values reflected similar treatment responses (P < 0.05), with a majority of the effects on muscle redness (CIE a*, hue angle) and measures of discoloration. Tasco steaks were generally more red and less discolored during extended postmortem aging and retail exposure (P < 0.05). The results from this study indicate that short-term supplementation of 2% Tasco meal in feedlot cattle increases carcass quality and prolonged retail shelf life.
Key Words: marbling • shelf-life • Tasco
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INTRODUCTION
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Tasco is a generally recognized as safe (GRAS)-approved feed additive produced from brown seaweed (Ascophyllum nodosum (L.) Le Jolis) that is commonly found in the coastal waters of the northern Atlantic Ocean. Tasco is produced as a granular meal (Allen et al., 2001b
) and as a water-soluble extract (Tasco-EX; Fike et al., 2001). Beef steers grazing Tasco-EX treated tall fescue (Festuca arundinacea Schreb.) pasture had greater marbling in retail cuts than steers that grazed nontreated fescue (Allen et al., 2001a). Further research by Allen et al. (2001a) concluded that addition of Tasco-EX to endophyte-infected pasture increased marbling score and tended to increase USDA quality grade. In a similar study, application of water soluble Tasco-EX to pastures resulted in beef steaks that were more red than steaks from steers that were grazed on untreated pastures (Montgomery et al., 2001).
The USDA Quality grade factors for beef cattle are generally regarded as important criteria used to predict the palatability of beef after cooking (Campion et al., 1975). Savell and Cross (1988) recommended a minimum intramuscular fat content, of which marbling score is closely related, of 3% for customer satisfaction and suggested that intramuscular fat improves bite, strain, lubrication, and insurance factors. Miller et al. (1997) reported that steaks from USDA Choice carcasses had greater palatability characteristics than steaks from carcasses that graded USDA Select.
Research indicates that the bright cherry-red color of fresh beef is used by consumers as an indicator of meat quality and wholesomeness (Cassens et al., 1988). It has been estimated that average value deterioration is 3.7% for the entire meat department and 5.4% for fresh meat as color deteriorates (Williams et al., 1992). Williams et al. (1992) also concluded that increasing case-life by 1–2 d would save the US meat industry $175 million to $1 billion (US) annually.
Thus, we conducted a study to evaluate the effectiveness of Tasco meal supplementation during the finishing period, in a commercial finishing operation, to alter carcass characteristics, sensory attributes, and retail display shelf life properties within postmortem aging periods and display days.
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MATERIALS AND METHODS
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All animals were handled according to an animal care and use protocol approved by the Texas Tech Animal Care and Use Committee.
Cattle and Carcass Evaluation
Two hundred Santa Cruz (1/2 Santa Gertrudis, ¹/3 Red Angus, and ¹/3 Gelbvieh) steers (n = 100) and heifers (n = 100), with an average initial pretrial BW of 226.8 ± 10.5 kg, were assigned randomly to treatment diets. All steers and heifers, with an average age of 6 mo, originated from a single calving season at a single commercial cattle operation in southern Texas. Steers and heifers were randomly assigned to dietary treatments, with equal portions of steers (n = 50) and heifers (n = 50) per treatment diet. Due to the constraints of the commercial finishing facility, all 100 animals within a treatment were placed in 1 pen. Heifers and steers were implanted twice throughout the finishing period with Revalor H and S, respectively (Intervet Inc., Millsboro, DE). Melengestrol acetate (Micro Beef, Amarillo, TX) was administered at approximately 0.5 mg per head per day mixed into the diet in the dry supplement package. Initial and reimplantation were administered on d 0 and approximately d 80 of a 170-d finishing period, respectively. Treatment diets consisted of the inclusion of 0 or 2% Tasco (Acadian Agritech, Dartmouth, Nova Scotia, Canada) in a granular meal form, on a DM basis, in a commercial steam rolled corn (Zea mays)-based diet (Table 1).
The commercial, corn-based diet consisted of 78% steam rolled corn, 5% cottonseed hulls, 6% alfalfa hay, 2% beef tallow, 4% molasses, and 5% dry supplement (DM basis; Table 1
). Treatment diet was fed on d 45 through 60 and d 156 through 170 of a 170-d finishing period. Supplement periods were established from prior pretrial inquiries (Braden et al., 2004; V. Allen, unpublished data). The commercial corn-based control diet was fed to all 200 animals between treatment periods (d 61 to 155). On d 171, cattle were transported to a commercial slaughtering facility located 75 km from the finishing facility. Left sides of all carcasses were retained after a 36-h postmortem chill and evaluated for USDA quality and yield grade characteristics, including lean maturity, skeletal maturity, LM marbling score, preliminary yield grade (PYG), adjusted preliminary yield grade (APYG), HCW, LM area, and percentage KPH (USDA, 1997), by trained Texas Tech University personnel.
Sample Collection and Preparation
Striploins (IMPS #180) and inside rounds (IMPS #168) were collected from each left carcass side (n = 200) and vacuum-packaged. Vacuum-packaged striploins and inside rounds were stored at 2°C until postmortem d 10. On postmortem d 10, striploins (n = 200) and inside rounds (n = 200) were removed from the packaging and serially sliced into four 2.54-cm-thick, subprimal steaks for proximate analysis, sensory, Warner-Bratzler shear force (WBSF), and retail display analysis, respectively. All subprimal striploin and inside round steaks for sensory, WBSF, and proximate analysis were then vacuum-packaged and stored at –26°C for further analysis. Primal striploins and inside rounds were then vacuum-packaged and stored at 2°C for subsequent postmortem aging and retail display analysis.
At postmortem d 17, 24, 31, and 38, primal striploins (n = 200) and inside rounds (n = 200) were again removed from the packaging, and a single 2.54-cm-thick steak was removed from the cranial end for retail display analysis. After each fabrication day within each postmortem aging period, primal strip-loins and inside rounds were repackaged and stored at 2°C until the following postmortem aging period. For retail display analysis, steaks were overwrapped with polyvinyl chloride (PVC) film, subjected to simulated retail display at 2°C for up to 5 d, and subjective and objective color measurements were evaluated daily by trained personnel.
Shear Force Determination
Striploin and inside round steaks for shear force analysis were thawed overnight at 2°C and cooked on a Magi-Grill belt grill (model TBG-60 Magigrill, Magi-Kitch’n Inc., Quakertown, PA) to an internal temperature of 71°C. Cooked steaks were then covered with PVC and chilled at 2°C for 24 h. Six cores (1.3 cm in diam.) were taken from each steak, parallel with the muscle fiber, and sheared once according to AMSA (1995) guidelines, with a WBSF attachment on a United Testing Machine (Cross-head speed = 200 mm/min; model #SSTM-500 with a tension attachment, United Calibration Corp., Huntington Beach, CA). Peak forces for all 6 cores of each steak were averaged, and cooking loss percentages were calculated.
Sensory Analysis
Striploin and inside round steaks for sensory analysis were thawed overnight at 2°C and cooked on a Magi-Grill belt grill (model TBG-60 Magigrill, MagiKitch’n) to an internal temperature of 71°C. Steaks were then trimmed of outside edges and cut into 1-cm3 cubes and stored in warming pans (approx. 4 min) for service to a trained sensory panel. A 6-member sensory panel that was trained according to Cross et al. (1978) evaluated 2 samples from each steak in a cubicle supplied with red light, the evaluation form, apple juice, and water for cleansing the palate and a cup for expectoration.
Steaks were evaluated using an 8-point hedonic scale (AMSA, 1995) for initial and sustained tenderness, flavor intensity, beef flavor, overall mouth-feel, and off-flavor, where 1 = extremely dry, tough, bland, uncharacteristic of beef, and uncharacteristic beef-like mouth-feel, and 8 = extremely juicy, tender, intense, characteristic of beef, and characteristic beef-like mouth-feel, respectively. Off-flavor was anchored, with 1 having no discernible off-flavor.
Proximate Analysis
Fat was removed along with large portions of connective tissue. Steaks were cut into 1.1-cm pieces, vitrified in liquid N, and homogenized with a Waring blender (model 1120, Waring Product Division, Dynamics Corporation of America, New Hartford, CT), placed in Whirl-Pak bags (Nasco, Modesto, CA) and stored at –26°C until analysis. Samples were analyzed in triplicate for moisture content utilizing AOAC method 8.2.1.1. Fat content was determined in triplicate utilizing the AOAC method 991.36 solvent extraction method. The AOAC method 992.15 was used for protein content determination with a Leco FP 2000 (Leco Corporation, St. Joseph, MI) protein analyzer. Leco FP 2000 operation procedures were used according to the manufacturer’s suggested operating instructions.
Retail Presentation
At each postmortem period, steaks were maintained under simulated retail display conditions. All steaks for color analysis were placed on Styrofoam trays, covered with PVC, and placed in a Hussman (Model M1 and M3, Hussman Corporation, Bridgeton, MO) retail display case at 2°C for 5 d. All steaks were subjected to 24-h, retail display, light exposure. Lighting environments were maintained utilizing GE Prelude X2 XL 7342 bulbs (General Electric, Cleveland, OH) that produced an illumination intensity of 1,900 lx at the surface of the steak.
Visual Color Analysis
During each 5-d postmortem period, steaks were evaluated daily by a trained panel, consisting of at least 6 members, for beef color, color uniformity, surface discoloration, and lean browning (8 = extremely bright cherry-red color, and 1= uniform lean color, no lean surface discoloration, and no discernible lean browning), according to the AMSA (1991) color guidelines.
Instrument Color Analysis
Commission Internationale de l’Eclairage (CIE) L* (muscle lightness), a* (muscle redness), b* (muscle yellowness), and reflectance spectra values were determined daily, through the overwrap PVC film, for each postmortem display day. Two random readings were taken on each steak with a Hunter Miniscan XE Plus (Model MSXP-4500C, Hunter Laboratories, Reston, VA) using illuminant D65 at 10° and a 3.5-cm aperture. Spectral reflectance values were determined and recorded every 10 nm over a range of 400 to 700 nm. The 2 random readings for each steak were averaged to obtain a representative measure of color. Muscle chroma (color intensity-saturation), hue angle (wavelength of light radiation [red, yellow, green, blue, and purple]), myoglobin (fresh muscle pigment), oxymyoglobin (oxygenated muscle pigment), and metmyoglobin (brown, oxidized muscle pigment) values were obtained utilizing the equations described by Hunt (1980) and Clydesdale (1991).
Statistical Analysis
Carcass, sensory, and proximate analysis data were analyzed as a completely randomized design in the GLM procedure (SAS Inst. Inc., Cary, NC). Marbling score, final yield, PYG, APYG, KPH, LM area, HCW, cooking loss, WBSF, sensory attributes, protein, moisture, and fat were included in the model, with treatment as a fixed effect. Chi-square analysis (PROC FREQ) was used to determine the frequency distribution of quality grade among treatments. Animal was used as the experimental unit.
Retail data were analyzed as a completely randomized design, with a split-plot in time (repeated measures) arrangement using PROC MIXED of SAS (Littell et al., 1996). Visual color, lean uniformity, lean discoloration, lean browning, L*, a*, b*, chroma, hue, myoglobin, oxymyoglobin, and metmyoglobin were included in the model, with treatment, display day, postmortem period, and all 2- and 3-way interactions as fixed effects. Sex (steer or heifer) was equally assigned to treatment diets and was analyzed as a random variable. Display day was analyzed as a repeated measure within postmortem period. Steak was the subject of the repeated statement and based on the AICC criteria, first order autoregressive was chosen as the optimum covariance structure (Littell et al., 1996). Animal was used as the experimental unit, and significant (P 
0.05) treatment effect means were separated using Fisher’s protected LSD.
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RESULTS AND DISCUSSION
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Carcass Characteristics
Carcasses from cattle supplemented with Tasco had greater marbling scores (Small 42 vs. Small 08) at slaughter than nonTasco-supplemented cattle (P = 0.003; Table 2). Carcasses from animals supplemented with Tasco had a greater frequency of USDA Choice and lower frequency USDA Select carcasses when compared with control (P = 0.001; Figure 1). Additionally, carcasses from Tasco-supplemented cattle had lower PYG and APYG (P = 0.006 and P = 0.02; respectively). Tasco supplementation had no effect (P > 0.05) on LM area, HCW, KPH, or final yield.
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Figure 1. Frequency distribution of USDA quality grades of carcasses from cattle supplemented with or without Tasco. a,bMeans within a quality grade comparison lacking a common superscript letter differ, P < 0.05.
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Research conducted by Allen et al. (2001a, b) found that cattle consuming Tasco-EX in feed or grazing Tasco-EX-treated tall fescue had increased marbling scores and a greater percentage of USDA Choice carcasses than nonTasco-EX supplemented cattle. The increase in marbling score in Tasco-treated cattle over that of the control in the current study resulted in more Tasco carcasses grading USDA Choice. Results from the current study with steers fed Tasco meal concur with those of Allen et al. (2001a) regarding increased USDA quality grade and marbling scores. Measures of PYG and APYG were statistically, but not biologically, significant (Table 2). Intramuscular fat generally occurs in concert with increased carcass fattening (Fiems et al., 2000). However, Tasco-supplemented cattle in the current study had greater intramuscular fat as indicated by marbling scores despite generally lower measures of external fattening when compared with control cattle. This is of interest for economic reasons because there is a desire to reduce the quantity of carcasses with excess external fat (Fiems et al., 2000) while increasing marbling.
Campion et al. (1975) reported that taste panel tenderness and overall acceptability were related to the quality grade of carcasses. There is considerable scrutiny and speculation as to the extent and function that marbling relates to beef palatability. Jones et al. (1991) concluded that the percentage of unacceptable ratings for steaks, based on overall palatability, declined from 38.5% for traces of marbling to 23.7% for modest. Additionally, considerable market value is placed on carcasses of the USDA Choice grade compared with USDA Select (Savell et al., 1987).
Sensory, Shear, and Proximate
Tasco supplementation had no effect (P > 0.05) on any of the evaluated sensory characteristics of striploin steaks, nor was there an effect (P > 0.05) of Tasco supplementation on striploin purge, cook-loss, WBSF, or proximate moisture content (Table 3.) Percent ether-extractable fat from Tasco striploin steaks was greater (4.53%) when compared with nonTasco (3.65%; P = 0.001). Tasco-supplemented animals had a lower percent protein in strip loin steaks (22.5%) compared with nonTasco animals (23.2%; P = 0.001).
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Table 3. Sensory, purge, cook-loss, and proximate attributes of striploin steaks from cattle supplemented with or without Tasco1
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Inside round steaks did not differ (P > 0.05) by treatment for initial and sustained juiciness, sustained tenderness, flavor intensity, beef flavor, overall mouth-feel, shear force, purge, cook-loss, and proximate attributes (Table 4). However, initial tenderness, off-flavor, and percent protein were affected by treatment (Table 4). Inside round steaks from Tasco-supplemented cattle were rated tenderer than the nonsupplemented control cattle (P = 0.03), but this effect diminished (P > 0.05) for sustained tenderness scores. Off-flavor scores for inside round steaks was lower (P = 0.002) because Tasco-supplemented animals were rated to have less off-flavor attributes when compared with the control animals. Additionally, Tasco steaks had a greater moisture content compared with nonTasco steaks (P = 0.03).
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Table 4. Sensory, purge, cook-loss and proximate attributes of inside round steaks from cattle supplemented with or without Tasco1
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In a national consumer survey conducted in 5 large metropolitan areas, Miller et al. (2001) found shear force values below 4.3 kg would be considered tender by 86% of surveyed consumers. The mean shear force values for both retail cuts in the current study were below the minimum shear force necessary (<4.3 kg) for beef to be rated tender by consumers regardless of treatment. Steers that grazed tall fescue treated with Tasco-EX, a form of Ascophyllum nodosum similar to Tasco, followed by conventional finishing in a feed-yard showed no effects of treatment on WBSF of striploin steaks (Montgomery et al., 2001). However, supplementing steers at 0, 1, and 2% of the diet (DM basis) with Tasco-EX during the final 2 wk of finishing did decrease WBSF in striploin steaks (V. Allen, unpublished data, 2000). Increased striploin ether extractable fat percentages for Tasco-supplemented animals appear to parallel quality grade findings in the current study (Table 2; Figure 1). The bite and strain theory, according to Savell and Cross (1988) suggests that intramuscular fat improves tenderness by reducing the bulk density and connective tissue strength. The lubrication effect may improve quality through increased juiciness. Additionally, Park et al. (2000) found beef loins with high intramuscular fat to have greater juiciness, tenderness, and flavor scores in comparison with lower intramuscular fat containing loin steaks. However, we found no discernible differences due to Tasco supplementation in sensory panel palatability measures for striploin steaks. In a similar study, Montgomery et al. (2001) found a significant effect of treatment on sustained tenderness of striploin steaks. Trained sensory panelist did not detect a significant difference between Tasco supplemented and nonTasco control inside round steaks for most of the evaluated attributes in the current study (P > 0.05; Table 3). Hence, there appears to be no negative effect of Tasco on the sensory properties of steaks from Tasco-supplemented cattle. This is of interest because supplementation strategies that increase beef marketability without negatively affecting any of the factors relating to palatability could be of significant benefit.
Retail Display Shelf Life
As expected, all visual and instrumental measures of lean color decreased and discoloration increased for striploin and inside round steaks with increased postmortem aging, days of retail display, and postmortem aging x days of retail display interaction (P < 0.001). However, several visual and instrumental measures of lean shelf life attributes and overall discoloration were influenced by Tasco supplementation and the interaction of Tasco supplementation with postmortem aging and retail display days.
Striploin (Longissimus Lumborum).
Visual color scores of striploin steaks decreased over simulated retail display and storage (data not shown) regardless of Tasco supplementation (P = 0.26), postmortem aging by Tasco supplementation interaction (P = 0.10), retail display day x Tasco supplementation interaction (P = 0.70) or postmortem aging x retail display day x Tasco supplementation interaction (P = 0.99). However, the decline in visual color uniformity scores were dependent upon a 3-way interaction of postmortem aging x retail display day x Tasco supplementation (P = 0.005; Figure 2). Striploin steaks from Tasco-supplemented animals were rated more uniform as shown by lower numerical uniformity scores in the last 2 retail display days of all postmortem aging periods, when compared with the nonTasco control. Striploin steaks from Tasco-supplemented and control animals were generally similar in the initial retail display day period; however, steaks from Tasco animals were generally more uniform by d 3 of all postmortem periods. The development of lean discoloration (Figure 3) and browning (Figure 4) was affected by Tasco supplementation dependent upon postmortem aging period and retail display day (P = 0.04 and 0.05, respectively). If striploin steaks were from Tasco-supplemented animals they were less discolored than nonTasco control steaks on d 5 of all postmortem aging periods; however, for lean browning scores this effect was only seen for postmortem periods 10 and 17. Nonetheless, striploin steaks were visually more uniform and less discolored by the final retail display period of all postmortem aging periods when compared with nonTasco controls.
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Figure 2. Visual lean uniformity scores of striploin steaks by retail display day within postmortem aging period from cattle supplemented with or without Tasco (least squares means ± SEM). aEffect of Tasco supplementation (P = 0.001); bpostmortem aging (P < 0.001); cretail display day (P < 0.001); dpostmortem aging x Tasco supplementation interaction (P = 0.30); eretail display day x Tasco supplementation interaction (P = 0.04); fpostmortem aging x retail display day interaction (P < 0.001); gpostmortem aging x retail display day x Tasco supplement interaction (P = 0.005). Tasco meal supplementation increased (P < 0.05) visual color uniformity of striploin steaks in final display periods of all postmortem aging periods. zColor uniformity (1 = uniform; 5 = extreme 2 toning); n = 88 and 89 for each Tasco-and nonTasco-supplemented cattle, respectively.
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Figure 3. Visual lean discoloration scores of striploin steaks by retail display day within postmortem aging period from animals finished with or without Tasco supplementation (least squares means ± SEM). aEffect of Tasco supplementation (P < 0.001); bpostmortem aging (P < 0.001); cretail display day (P < 0.001); dpostmortem aging x Tasco supplement interaction (P = 0.38); eretail display day x Tasco supplement interaction (P = 0.21); fpostmortem aging x retail display day interaction (P < 0.001); gpostmortem aging x retail display day x Tasco supplement interaction (P = 0.04). Tasco meal supplementation decreased lean discoloration of striploin steaks in latter display periods of all postmortem aging periods. zLean discoloration [1 = none; 7 = total (100%)]; n = 88 and 89 for each Tasco and nonTasco mean, respectively.
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Figure 4. Visual lean browning scores of striploin steaks by retail display day within postmortem aging period from animals finished with or without Tasco supplementation (least squares means ± SEM). aEffect ofTasco supplementation (P = 0.02); bpostmortem aging (P < 0.001); cretail display day (P < 0.001); dpostmortem aging x Tasco supplement interaction (P = 0.36); eretail display day x Tasco supplement interaction (P = 0.84); fpostmortem aging x retail display day interaction (P < 0.001); gpostmortem aging x retail display day x Tasco supplement interaction (P = 0.05). Tasco meal supplementation decreased visual lean browning of striploin steaks in the last retail display period of postmortem aging periods 10 and 17. zLean browning (1 = none; 6 = dark brown); n = 88 and 89 for each Tasco and nonTasco mean, respectively.
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Instrumental CIE L* values were not affected by Tasco supplement nor dependent upon postmortem aging, retail display day, or postmortem aging x retail display day Tasco supplement interaction (P = 0.30, 0.94, 0.24, and 0.96; respectively; data not shown). Conversely, CIE a* and b* value decline was dependent upon a Tasco treatment x postmortem aging period interaction (P = 0.001; Figure 5). Lean a* value (Figure 5), a measure of red (positive values) to green (negative values) decline over periods of postmortem aging, but steaks from Tasco-fed beef animals had greater overall values, being more red when compared with nonTasco-fed beef animals on postmortem aging periods 10, 17, and 24. This effect diminished in the last 2 postmortem aging periods. Striploin chroma values, a measure of total color saturation (greater values indicate a more brilliant color), were also affected by a Tasco supplement x postmortem aging period interaction (P = 0.001; Figure 6). Chroma values were similar for Tasco and nonTasco animals for postmortem period 10, but Tasco striploin steaks had greater chroma values in intermediate postmortem periods 17 and 24. The effect of Tasco treatment on chroma values diminished (P > 0.05) by the final 2 postmortem aging periods. Striploin hue angle value (0° = true red to 90° = true yellow) was greater (P < 0.001; data not shown), indicating a less red color, for nonTasco animals (45.62) when compared with Tasco-supplemented animals (43.48), regardless of postmortem aging period, retail display day or postmortem aging period x retail display day interaction (P = 0.09, 0.40, and 0.86, respectively). Instrumental estimates of steak lean pigments found no difference due to Tasco supplementation or Tasco by aging and display interaction for myoglobin percentage (P > 0.05; data not shown). However, oxymyoglobin (P = 0.004) and metmyoglobin (P = 0.006) values were dependent upon treatment regardless of postmortem aging or simulated retail display exposure (data not shown). Steaks from Tasco-fed animals had greater oxymyoglobin values (62.19 vs. 61.19) when compared with nonTasco-fed beef steaks. The inverse trend was seen for metmyoglobin values; Tasco-fed beef steaks had lower percentages of oxidized pigment (34.97) when compared with nonTasco (35.73).
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Figure 5. Instrumental CIE a* and b* values of striploin steaks by postmortem aging period from animals finished with or without Tasco supplementation (least squares means ± SEM). aEffect of Tasco supplementation (P = 0.001); bTasco supplementation (P = 0.85); cpostmortem aging (P < 0.001); dretail display day (P < 0.001); epostmor-tem aging x Tasco supplement interaction (P < 0.01); fretail display day x Tasco supplement interaction (P > 0.15); gpostmortem aging x retail display day interaction (P < 0.001); hpostmortem aging x retail display day x Tasco supplement interaction (P > 0.84); yLean a* value (positive = red, 0 = neutral, negative = green). zLean b* value (positive = yellow, 0 = neutral, negative = blue); n = 88 and 89 for each Tasco and nonTasco mean, respectively.
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Figure 6. Instrumental chroma values of striploin steaks by postmortem aging period from animals finished with or without Tasco supplementation (least squares means ± SEM). aEffect of Tasco supplementation (P = 0.004); bpostmortem aging (P < 0.001); cretail display day (P < 0.001); dpostmortem aging x Tasco supplement interaction (P = 0.001); eretail display day x Tasco supplement interaction (P = 0.18); fpostmortem aging x retail display day interaction (P < 0.001); gpostmortem aging x retail display day x Tasco supplement interaction (P = 0.92). Striploin steaks from Tasco-supplemented animals had greater chroma values in postmortem periods 17 and 24. zLean chroma value (numerically increasing color saturation); n = 88 and 89 for each Tasco and nonTasco mean, respectively.
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Inside Round (Semimembranosus).
Panelist scores for inside visual color were greater (P < 0.05) for Tasco-fed beef steaks when compared with nonTasco-fed beefsteaks in extended periods of simulated retail display day exposure of all postmortem aging periods (Tasco x postmortem aging x display day interaction; P = 0.05; Figure 7). Differences in visual color generally increased in magnitude by postmortem aging periods. Visual color scores were similar (P > 0.05) for Tasco-fed beef and nonTasco-fed beef steaks in initial (d 1) display periods of postmortem aging intervals 10 and 17, but Tasco-fed beef steaks were rated lower (P < 0.05) for visual color on initial display periods in postmortem periods 24, 31, and 38. However, this trend reversed by d 2 of all postmortem aging periods. Tasco supplementation, dependent upon postmortem aging period and retail display day, increased visual lean uniformity, decreased lean discoloration, and decreased lean browning (P < 0.001; Figure 8, 9, and 10). Tasco fed beef inside round steaks, compared with nonTasco-fed beef, were rated more uniform in lean color on d 1 of all postmortem aging periods; however, uniformity differences due to Tasco supplementation diminished (P > 0.05) with extended days of retail display across postmortem intervals. Conversely, Tasco-fed beef inside round steaks had greater (P < 0.05) overall discoloration and browning in the initial retail display period when compared with nonTasco-fed beef steaks; however, with increased exposure to simulated retail display conditions this trend reversed, as Tasco-fed beef steaks were generally rated by panelist to be less (P > 0.05) discolored and brown by the final display day.
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Figure 7. Visual lean color scores of inside round steaks by retail display day within postmortem aging period from animals finished with or without Tasco supplementation (least squares means ± SEM). aEffect of Tasco supplementation (P = 0.03); bpostmortem aging (P < 0.001); cretail display day (P < 0.001); dpostmortem aging x Tasco supplement interaction (P = 0.16); eretail display day x Tasco supplement interaction (P = 0.001); fpostmortem aging x retail display day interaction (P < 0.001); gpostmortem aging x retail display day x Tasco supplement interaction (P = 0.05). Tasco meal supplementation increased visual color scores of inside round steaks over display periods of all postmortem aging intervals. zLean color (1 = extremely dark red; 8 = extremely bright cherry-red); n = 88 and 89 for each Tasco and nonTasco mean, respectively.
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Figure 8. Visual lean uniformity scores of inside round steaks by retail display day within postmortem aging period from animals finished with or without Tasco supplementation (least squares means ± SEM). aEffect of Tasco supplementation (P = 0.42); bpostmortem aging (P < 0.001); cretail display day (P < 0.001); dpostmortem aging x Tasco supplement interaction (P = 0.31); eretail display day x Tasco supplement interaction (P = 0.001); fpostmortem aging x retail display day interaction (P < 0.001); gpostmortem aging x retail display day x Tasco supplement interaction (P < 0.001). zLean uniformity (1 = uniform; 5 = extreme 2-toning); n = 88 and 89 for each Tasco and nonTasco mean, respectively.
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Figure 9. Visual lean discoloration scores of inside round steaks by retail display day within postmortem aging period from animals finished with or without Tasco supplementation (least squares means ± SEM). aEffect of Tasco supplementation (P = 0.12); bpostmortem aging (P < 0.001); cretail display day (P < 0.001); dpostmortem aging x Tasco supplement interaction (P = 0.08); eretail display day x Tasco supplement interaction (P = 0.001); fpostmortem aging x retail display day interaction (P < 0.001); gpostmortem aging x retail display day x Tasco supplement interaction (P < 0.001). zLean discoloration (1 = none; 7 = total discoloration); n = 88 and 89 for each Tasco and nonTasco mean, respectively.
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Figure 10. Visual lean browning scores of inside round steaks by retail display day within postmortem aging period from animals finished with or without Tasco supplementation (least squares means ± SEM). aEffect of Tasco supplementation (P = 0.11); bpostmortem aging (P < 0.001); cretail display day (P < 0.001); dpostmortem aging x Tasco supplement interaction (P = 0.32); eretail display day x Tasco supplement interaction (P = 0.001); fpostmortem aging x retail display day interaction (P < 0.001); gpostmortem aging x retail display day x Tasco supplement interaction (P < 0.001). zLean browning (1 = none; 8 = dark brown); n = 88 and 89 for each Tasco and nonTasco mean, respectively.
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Inside round lean L* values were not affected by Tasco supplementation, Tasco x postmortem aging interaction, Tasco x retail display day, or Tasco x postmortem aging x display day (P = 0.29, 0.84, 0.06, and 0.25, respectively; data not shown). Inside round steak a* values decreased (P < 0.05) over postmortem aging periods as expected; however, this decline was dependent upon a Tasco x postmortem aging-retail display day interaction (P = 0.001; Figure 11). Tasco-fed beef steaks had greater (P < 0.05) a* values on display d 4 and 5 of postmortem periods 10, 17, 24, and 31, but these differences were not apparent (P > 0.05) by postmortem d 38. Lean b* values were also dependent upon a 3-way interaction of Tasco, aging period, and display day (P = 0.001; Figure 12). Color saturation values (chroma) were greater for Tasco-fed beef steaks similar to lean a* value trends, when compared with steaks from non-Tasco-supplemented animals and this effect diminished, similarly by postmortem interval 38 (Tasco x postmortem aging x display day interaction, P < 0.001; Figure 13). Differences due to Tasco supplementation on hue angle values were reliant upon display day (P = 0.001; Figure 14); Tasco-fed beef steaks were found to be more true red (P < 0.05) when compared with nonTasco inside round steaks. Upon analyzing estimated muscle pigment instrument values, no effect of treatment or interaction with aging and display day was found for the initial pigment myoglobin (Tasco supplement, P = 0.25; Tasco x postmortem aging, P = 0.28, Tasco x display day, P = 0.99; Tasco x postmortem aging x display day, P = 0.71; data not shown). However, there was an effect of Tasco supplementation, dependent upon retail display day for lean oxymyoglobin and metmyoglobin values (P 0.003; Figure 15). Metmyoglobin values were lower (P < 0.05), and oxymyoglobin values were greater (P < 0.05) by display d 4 and 5 of Tasco-fed beef than nonTasco-fed beef steaks, regardless of postmortem aging period.
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Figure 11. Instrumental CIE a* values of inside round steaks by retail display day within postmortem aging period from animals finished with or without Tasco supplementation (least squares means ± SEM). aeffect of Tasco supplementation (P < 0.001); bpostmortem aging (P < 0.001); cretail display day (P < 0.001); dpostmortem aging x Tasco supplement interaction (P = 0.03); eretail display day x Tasco supplement interaction (P = 0.01); fpostmortem aging x retail display day interaction (P < 0.001); gpostmortem aging x retail display day x Tasco supplement interaction (P = 0.001). zLean a* value (positive = red, 0 = neutral, negative = green); n = 88 and 89 for each Tasco and nonTasco mean, respectively.
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Figure 12. Instrumental CIE b* values of inside round steaks by retail display day within postmortem aging period from animals finished with or without Tasco supplementation (least squares means ± SEM). aEffect of Tasco supplementation (P = 0.004); bpostmortem aging (P < 0.001); cretail display day (P < 0.001); dpostmortem aging x Tasco supplement interaction (P = 0.23); eretail display day x Tasco supplement interaction (P = 0.69); fpostmortem aging x retail display day interaction (P < 0.001); gpostmortem aging x retail display day x Tasco supplement interaction (P = 0.001). zLean b* value (positive = yellow, 0 = neutral, negative = blue); n = 88 and 89 for each Tasco and nonTasco mean, respectively.
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Figure 13. Instrumental chroma values of inside round steaks by retail display day within postmortem aging period from animals finished with or without Tasco supplementation (least squares means ± SEM). aEffect of Tasco supplementation (P < 0.001); bpostmortem aging (P < 0.001); cretail display day (P < 0.001); dpostmortem aging x Tasco supplement interaction (P = 0.08); eretail display day x Tasco supplement interaction (P = 0.18); fpostmortem aging x retail display day interaction (P < 0.001); gpostmortem aging x retail display day x Tasco supplement interaction (P < 0.001). zLean chroma value (numerically increasing color saturation); n = 88 and 89 for each Tasco and nonTasco mean, respectively.
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Figure 14. Instrumental hue values of inside round steaks by retail display day from animals finished with or without Tasco supplementation (least squares means ± SEM). aEffect of Tasco supplementation (P = 0.001); bpostmortem aging (P < 0.001); cretail display day (P < 0.001); dpostmortem aging x Tasco supplement interaction (P = 0.05); eretail display day x Tasco supplement interaction (P = 0.001); fpostmortem aging x retail display day interaction (P < 0.001); gpostmortem aging x retail display day x Tasco supplement interaction (P = 0.93). zLean hue value (numerically increasing true red color); n = 88 and 89 for each Tasco and nonTasco mean, respectively.
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For consumers, desirable fresh beef color is bright-pink to bright-red, and any deviation from this creates a degree of unacceptability (Kropf, 1980). Faustman et al. (1989) concluded that an extremely crucial component of fresh red meat appearance was color, and any means to stabilize meat color would increase the product’s shelf life and positively affect economic values in the beef chain. Smith et al. (1996) concluded the quality deterioration in meat occurs mainly because of the oxidation of lipids and muscle pigments. Research conducted by Smith et al. (1996) further found that maintaining or extending case-life of retail cuts by assuring that they have bright-pink to bright-red color can be accomplished by delaying the breakdown of lipid and thus delaying meat discoloration. Results of the current experiment suggest that supplementation with Tasco during the finishing period increases the desirable red color of retail cuts of meat. These results are in agreement with results reported from cattle grazing Tasco-EX-treated tall fescue pastures (Montgomery et al., 2001) and when Tasco-EX was directly supplemented to steers during the final 14 d in feedyard finishing (V. Allen, unpublished data).
Ascophyllum nodosum (Tasco) is a known source of plant growth regulators, and has increased activity of the antioxidant superoxide dismutase and specific vitamin precursors (Allen et al., 2001b; Fike et al., 2001). It is known that seaweeds contain substituted phenols and poly-phenols, a class of compounds that include effective antioxidants (LeTutor, 1990). Results from Tasco-treated pasture studies suggest a relationship between Tasco treatment and upregulation of antioxidant activities in the forage and steers that grazed those pastures (Allen et al., 2001b; Fike et al., 2001; Montgomery et al., 2001) suggesting that a relationship between vitamin E and Tasco supplementation may exist. However, direct supplementation of Tasco-EX to steer in the final 14 d of finishing revealed no effect of treatment on vitamin E status in liver, striploin, or round steaks (V. Allen, unpublished data). A slight increase in serum vitamin E was observed only at the greatest level of supplementation.
As in the current study, Montgomery et al. (2001) found that steaks were more uniform and had less discoloration and less browning if they were from steers that had grazed Tasco-treated forages and concluded water-soluble Tasco applied to forage during the grazing season can improve color stability and extend beef shelf life. Direct supplementation of Tasco extract to steers during the final 14 d on finishing in feeding facilities has shown similar characteristics of shelf life extension in strip-loin steaks (V. Allen, unpublished data, 2000).
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IMPLICATIONS
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Tasco meal supplementation in finishing diets may increase the amount of intramuscular fat and therefore increase marbling score and US Department of Agriculture quality grade. Additionally, Tasco meat supplementation may increase shelf life in advanced aging and retail display periods. Use of natural feed additives to effectively alter intramuscular marbling as well as extend shelf life could prove a viable alternative to current industry supplementation strategies focused on similar outcomes.
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Footnotes
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1 This work was supported from grants and funding supplied by National Cattlemen’s Beef Association, Texas Beef Council, the San Antonio Livestock Exposition and the Houston Livestock Show and Rodeo. 
2 Current address: Department of Agriculture, Angelo State University, San Angelo, TX 76909.
3 Corresponding author: mfmrraider{at}aol.com
Received for publication May 5, 2006.
Accepted for publication September 1, 2006.
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LITERATURE CITED
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Abstract
INTRODUCTION
0.08); ere-tail display day x Tasco supplement interaction (P