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Department of Animal Sciences, University of Florida, Gainesville 32611-0910
3 Correspondence:
P.O. Box 110910 (phone: 352-392-1922; fax: 352-392-7652; E-mail:
johnson{at}animal.ufl.edu).
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Abstract |
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 Top Abstract IntroductionMaterials and MethodsResults and DiscussionImplicationsLiterature Cited |
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Key Words: Beef • Color • Implant • Quality
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Introduction |
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TopAbstractIntroductionMaterials and MethodsResults and DiscussionImplicationsLiterature Cited |
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Morgan (1997) concluded that carcass quality can be compromised due to reduced marbling scores and greater incidence of dark cutters potentially caused by anabolic growth promotants, and Foutz et al. (1997) suggested that implant programs that included TBA might negatively influence skeletal maturity and shear force values. Platter et al. (2001) also found significant reductions in intramuscular fat deposition and decreased meat tenderness associated with TBA-implanted steers in the finishing phase of production.
Recent research has indicated that supranutritional levels of vitamin D3 supplemented approximately 7 to 10 d preharvest may improve tenderness of fresh beef (Swanek et al., 1999; Montgomery et al., 2000), but effects on fresh beef color or physiological maturity have not been reported.
Thus, the purpose of these studies was to objectively evaluate the effect of TBA-estradiol implants and vitamin D3 supplementation on fresh beef muscle quality, color, and physiological maturity.
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Materials and Methods |
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TopAbstractIntroductionMaterials and MethodsResults and DiscussionImplicationsLiterature Cited |
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Feeding and Implant Management. Over a 2-yr period, 123 steers that initially averaged 260 ± 5 kg were randomly allotted to one of three implant treatments. Steers ranged in age from approximately 6 to 10 mo upon start of the trial, and breed types included both purebred Angus steers and Brahman-influenced crossbred animals. Cattle were fed in 12 small groups of approximately six animals each, where at least two animals of each implant treatment were represented. Additionally, within each pen, animals were of similar age and breed composition. Thus, age and breed differences were equally stratified across all treatments. Over the 2-yr period, 40 steers were not implanted and served as controls, 41 steers were implanted with Ralgro (36 mg of zeranol; Schering Plough, Madison, NJ) on d 0 and reimplanted on d 56 with Revalor-S (120 mg of trenbolone acetate and 24 mg of estradiol; Hoeschst-Roussel Agri-Vet Co., Somerville, NJ) (RAL-REV), and 42 steers were implanted with Revalor-S on both d 0 and d 56 (2REV). After administration of the second implant, cattle were fed for a minimum of 100 d. Cattle consumed a diet that contained 77.5% whole-shelled corn, 10.4% cottonseed hulls, 6.9% molasses, and 5.2% commercial supplement on a dry matter basis. Since equivalent numbers of cattle associated with each treatment were fed together, the only performance measure evaluated was ADG. When harvested, equal numbers of steers from each treatment were harvested.
Carcass Treatment. Animals were harvested at the meat processing facility at the University of Florida. Each carcass was electrically stimulated between hide removal and evisceration with 500 V, 3 to 6 amps in 17 1-s impulses allowing a 2-s interval between impulses. At 40 h postmortem, carcasses were evaluated for yield and quality factors (USDA, 1997) by trained university personnel. At 48 h postmortem, a 5-cm section of the loin was removed, vacuum packaged using Cryovac B620 barrier bags (3 to 6cc/m2, 24 h, 1 atm at 4.5°C, 0% relative humidity; Sealed Air Corp., Duncan, SC), and stored at 2 ± 2°C for a total of 14 d. After the 14-d aging period, packages were opened, and two (2.54-cm-thick) steaks were cut from each loin section. One steak was immediately frozen for subsequent Warner-Bratzler shear (WBS) determination, and the second steak was used for retail display evaluation.
Retail Display Evaluation. Steaks used for retail display evaluation were placed in a styrofoam tray and overwrapped with a polyvinyl chloride film (oxygen transmission rate = 6,500 mL/m2/ 24 h at 0% relative humidity). Steaks were displayed under GE "cool white" fluorescent lamps for a 12 h on, 12 h off cycle in a Hill (Hill Refrigeration Div, Trenton, NJ) open-top retail case at 2 ± 3°C. A four-member, experienced panel evaluated each steak for muscle color (8 = bright cherry red; 1 = extremely dark red) and surface discoloration (0 to 100%). Steaks were initially evaluated 45 min after removal from vacuum (d 0) and then at 1, 2, and 3 d after retail packaging. Loin steaks were also objectively evaluated for color using a Minolta CR-100 Chroma Meter (Minolta Corp., Ramsey, NJ) with an 8-mm measuring aperture utilizing illuminant C. On each day of retail display, color measurements were taken at three separate locations on each steak and recorded. Objective color measures were expressed as L*, a*, and b* color space values (also referred to as the CIELAB color space). L* values depict brightness where larger values are brighter; a* values depict red and green colors where higher values have more red; and b* values depict yellow and blue colors where higher values have more yellow. As values for a* and b* move further from zero, colors become "brighter."
Shear Force Analysis. One loin steak from each animal was cooked on a Farberware Open-Hearth (Farberware Products, Nashville, TN) broiler (AMSA, 1995). Internal temperature was monitored by placing a copper-constantan thermocouple in the geometric center of each steak, and thermocouples were attached to a recording potentiometer. Steaks were cooked to an internal temperature of 35°C, turned, and cooked to a final internal temperature of 71°C. Steaks were cooled 18 h at 2 ± 3°C and a minimum of six 1.27-cm cores were removed from each steak parallel to the orientation of the fibers. Shear force was determined on an Instron Universal Testing machine (Instron Corp., Canton, MA) equipped with a WBS attachment (crosshead speed 200 mm/min).
Objective Determination of Physiological Maturity. Additionally, 3 cartilaginous buttons from the dorsal processes of the 9th to 11th thoracic vertebrae were removed 24 h postmortem and stored frozen (-20°C) until analyzed for ash content as an objective determinant of physiological maturity (Waggoner et al., 1990).
Statistical Design and Analysis. This trial used a randomized complete block design where each pen served as a block. Within each of the twelve pens, equal numbers of animals received each of the three different treatments. The GLM procedure of SAS was used to analyze the data using days on feed as a covariate with variation due to pen removed. For data analyzed, information was collected on the individual animal or carcass, which served as the experimental unit for the study.
Experiment 2
Feeding and Implant Management. Over a 2-yr period, 166 yearling steers that initially averaged 323 ± 4 kg were randomly allotted within breed type to one of two implant treatments and one of two vitamin D3 preharvest supplementation treatments that resulted in a 2 x 2 factorial arrangement of treatments used in this experiment. Breed types included purebred Angus, purebred Brahman, and crosses of the two breeds (25% Angus, 75% Brahman; 50% Angus, 50% Brahman; and 75% Angus, 25% Brahman). One-half of the steers were implanted with Component TE-S (VetLife L.L.C., West Des Moines, IA) on d 1 of the trial, and steers were not reimplanted during the finishing phase. The active ingredients of Component TE-S include 120 mg of trenbolone acetate and 24 mg of estradiol. Control steers were never implanted. Throughout the finishing phase, steers were fed the same basic diet as those of Exp. 1.
After steers had been on full feed for 90 d, they were individually evaluated by ultrasonography using an Aloka SSD-500V with a UST-5044 transducer (Carometrics Medical Systems, Wallingford, CT), between the 12th–13th-rib interface. When individual animals reached a compositional endpoint of 11 mm fat thickness opposite the longissimus muscle (LM) at three-quarters the distance from the dorsal aspect of the muscle, they were selected for harvest. One-half of the steers within each implant treatment and breed type group selected for harvest were segregated. Each of those steers were then fed 5 million IU/d of vitamin D3 from Rovimix D3 500 DLC (Roche Vitamins, Inc., Parsippany, NJ) for seven consecutive days. A vitamin D3 premix that used ground corn as the carrier was substituted for whole corn in the final diet on a 1:1 basis and was thoroughly mixed using a large horizontal mixer. The balance of cattle selected for harvest continued to consume the base finishing diet.
Carcass and Sample Treatment. Steers were harvested at a commercial packing plant and subsequently chilled for 24 h prior to grading. Electrical stimulation was unavailable and not used in this commercial plant. After chilling, carcasses were evaluated for yield and quality grade factors (USDA, 1997) by experienced university personnel. Once carcass characteristics were determined, a section of the beef shortloin (#174; NAMP, 1997) was removed from one side and transported under refrigeration to the University of Florida Meats Laboratory for subsequent packaging and analysis. Three 2.54-cm-thick steaks were removed from the loin and vacuum packaged as described for Exp. 1. Two steaks were aged for either 5 or 14 d postmortem and subsequently used for WBS force analyses. The third steak available from the loin section was used for the retail display evaluation, after 14-d postmortem aging. All other postmortem handling procedures and analyses were conducted as described for Exp. 1.
Statistical Design and Analysis. Data were analyzed as a randomized complete block design with treatments arranged in a 2 x 2 factorial design using the GLM procedures of SAS (SAS Inst. Inc., Cary, NC). Breed type served as the block, and variation due to differences in the six breed types (100% Angus, 75% Angus; 25% Brahman, 50% Angus; 50% Brahman, 25% Angus; 75% Brahman, 100% Brahman; and Brangus) was removed in the model. For data analyzed, information was collected on the individual animal or carcass, which served as the experimental unit for the study.
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Results and Discussion |
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TopAbstractIntroductionMaterials and MethodsResults and DiscussionImplicationsLiterature Cited |
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Performance and basic carcass data are presented in Table 1
. Implanted cattle gained 20% faster (P < 0.05) than control steers during the feeding period and produced approximately 29 kg more (P < 0.05) carcass weight at harvest. Similar performance advantages have been reported for cattle implanted with TBA-based implants (Bartle et al., 1992; Johnson et al., 1996; Hermesmeyer et al., 2000).
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Implants reduced (P < 0.05) marbling scores 31 to 44 percentage units compared to non-implanted controls, which is similar to that reported by Duckett et al. (1999). Approximately 50% of the control steer carcasses graded U.S. Choice, but only 18% of the RAL-REV and 21% of the 2REV treated steers produced carcasses that qualified for the U.S. Choice quality grade. A review by Duckett et al. (1996) reported that marbling scores were reduced 24% and the number of carcasses that graded choice was reduced 15%, on average, due to the usage of growth promotants. Herschler et al. (1995) also reported that implants containing a 1:5 or 1:10 ratio of estradiol and TBA decreased marbling scores of steers. Similarly, Hermesmeyer et al. (2000) reported that steers implanted with Revalor-S had lower marbling scores than nonimplanted cattle. However, even the implanted cattle within their study had average marbling scores of Small70, which is adequate for the low Choice quality grade. Although Revalor implants administered at d 30 and again at d 130 of the finishing period did not affect the percentage of Choice and Prime carcasses, implant regiments that employed three successive implants had detrimental effects on quality grade (Samber et al., 1996).
Physiological maturity of carcasses from implanted steers was more advanced (P < 0.05) as evaluated by the percentage of ash present in the 9th to 11th thoracic cartilaginous vertebrae and subjective skeletal maturity evaluations (Table 1
). The percentage of ash detected in the cartilaginous buttons of the thoracic vertebrae increased (P < 0.05) from 2.00% (controls) to 3.12 (RAL-REV) and 4.15% (2REV). In a study that used 30-mo-old heifers that had produced one calf, Waggoner et al. (1990) also reported a trend for increased calcium deposition in the thoracic buttons of implanted (3.87 ± 0.44%) vs nonimplanted (3.19 ± 0.42%) 30-month-old heifers. Bone maturity scores increased (P < 0.05) from A39 (control) to A64 (2REV). These changes in skeletal maturity are similar to those reported by Foutz et al. (1997). In both studies, however, carcasses from all implant treatments were easily within the "A" maturity range. These effects pose minimal quality grade implications for carcasses from implanted steers given the current USDA standards but could impact quality grade if animals were more mature at the beginning of the finishing phase.
Lean maturity scores of carcasses from 2REV treated steers were more advanced (P < 0.05) than lean maturity scores from nonimplanted animals. Carcasses from the RAL-REV treated steers were intermediate in lean maturity and not statistically different from the controls or 2REV treated animals. Herschler et al. (1995) also observed darker but acceptable lean color of the LM from implanted cattle.
Lean brightness as evaluated by L* values were not affected by implant treatment over the 3-d retail case evaluation period (Table 2). Loin steaks from 2REV treated animals had lower (P < 0.05) a* values initially (d 0) and at d 3 than did loin steaks from the controls. The RAL-REV a* values for lean color were intermediate and not different than a* values for the other two treatments. A reduction in a* value represents less red and more green coloration. Implant treatment did not affect a* values on d 1 and d 2 of display. A reduction (P < 0.05) in b* values was noted on d 0 for loin steaks from RAL-REV treated animals compared to controls, whereas steaks from 2REV treatments were intermediate and not statistically different from the other two treatments. At d 1 and d 3 of evaluation, loin steaks from 2REV treated steers had lower (P < 0.05) b* values than controls. The RAL-REV was intermediate to the other two treatments. Lean is perceived as darker in color if L*, a*, and b* values are lower (Wulf and Wise, 1999), and Wulf et al. (1997) showed that meat with lower b* values was less tender.
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) than steaks from control steers (3.06 vs 3.58 kg). Shear force of steaks from RAL-REV steers was intermediate (3.28 kg) between the control and 2REV treatments. Similarly, Foutz et al. (1997) indicated that steaks from implanted cattle required approximately 0.40 kg more shear force than steaks from nonimplanted cattle, and the percentage of tough steaks increased from 21% (controls) to 34% (implanted). In contrast, Schoonmaker et al. (2001) reported no differences in shear force values or taste panel evaluations of tenderness between cattle aggressively implanted (Synovex-C administered at approximately 140 d of age, followed by two successive Revalor-S implants administered during the feedlot phase) and nonaggressively implanted (two Synovex-S implants successively administered during the feedlot phase). Use of androgenic or combination implants had no effect on beef tenderness of strip loin, top sirloin, or top round steaks, but estrogenic implants decreased tenderness of top sirloin steaks (Gerken et al., 1995).
Table 3 shows color evaluation scores of an experienced panel for muscle color and surface discoloration after 14 d of vacuum aging. Evaluators were unable to detect any significant differences in muscle color or surface discoloration of steaks packaged in polyvinyl chloride overwrapped foam trays due to implant treatments. The absence of visually detectable differences in meat color that were detected by Chroma Meter evaluations suggests that perhaps the instrument evaluation was more sensitive to subtle color changes than were visual evaluations.
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The main effects of implant treatment and vitamin D3 feeding on ADG, carcass traits, and WBS values for Exp. 2 are presented in Table 4. Similar to the results for Exp. 1, implanted steers gained approximately 19% faster (P < 0.01) than nonimplanted steers and produced heavier (P < 0.01) carcasses with less (P < 0.01) kidney, pelvic, and heart fat, and larger (P < 0.01) LM area. These results compare favorably with those of Johnson et al. (1996) who used the same basic implant regimen as was used in the current study. Carcasses from implanted steers also had more advanced (P < 0.01) bone maturity scores, and higher (P < 0.01) ash content of the cartilaginous tips of the dorsal processes of the 9th to 11th thoracic vertebrae. Warner-Bratzler shear values for loin steaks aged for 5 d were approximately 9% higher (P < 0.05) for implanted steers than nonimplanted steers, although no significant difference for shear values were identified for LM steaks aged 14 d. Similarly, Roeber et al. (2000) reported lower WBS force values for steaks from control steers than from steers implanted with a single Revalor-S implant, and consumers rated the steaks from nonimplanted cattle as more tender.
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Other carcass traits and shear values were not significantly affected by vitamin D3 feeding. Scanga et al. (2001) reported supplementation of cattle with 1 to 5 million IU D3/d for 8 d preharvest did not improve WBS force values of cooked steaks after 2, 7, 14, or 21 d of postmortem aging compared to steaks from cattle not supplemented with vitamin D3. In contrast, strip loin and top loin steaks from cattle administered 5 or 7.5 x 106 IU of vitamin D3 through a bolus for nine consecutive days preharvest had lower WBS values at 14 d postmortem, but were not significantly different from controls after 3, 7, or 21 d of aging (Montgomery et al., 2000). In other studies, Swanek et al. (1999) observed reduced WBS values at 7 d postmortem when cattle were supplemented with 5 x 106 IU of vitamin D3 daily for 7 d prior to harvest or at 7 and 14 d postmortem when supplemented with 7.5 x 106 IU of vitamin D3 daily for 7 d. However, supplemental vitamin D3 did not improve tenderness, juiciness, flavor, or overall palatability scores of strip loins aged for 14 d enough that differences could be detected by a 10-member trained sensory panel (Montgomery et al., 2000).
Tables 5 and 6 represent chromaticity and panel evaluations of meat color and discoloration. Implant treatment did not affect L*, a*, or b* values for meat color in Exp. 2. These animals did not receive growth promotants prior to the feeding phase of this project, and those animals that were implanted received only one implant prior to harvest. The implant strategy used was less aggressive than that employed in Exp. 1 because cattle were not reimplanted with Revalor-S prior to harvest. Revalor-S administered to Holstein steers 245 d prior to harvest had no effect on carcass traits including marbling, percentage of choice carcasses, and subjective lean color scores (Comerford et al., 2001).
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) were noted between implant treatment and vitamin D3 feeding for panel evaluations of muscle color and surface discoloration, and these interaction means are given in Table 7. Loin steaks from implanted steers that were fed vitamin D3 were darker (P < 0.05) in lean color on d 3 of evaluation than were steaks from implanted steers that were not fed vitamin D3. Implanted steers that were either supplemented or not with vitamin D3 produced loin steaks with lean color that was intermediate and not different from each other for d 3 color evaluation.
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) for the significant interaction between implant treatment and vitamin D3 feeding for surface muscle discoloration for d 1 of display revealed that loin steaks from nonimplanted/nonvitamin D3 supplemented animals and implanted/vitamin D3 fed steers had significantly more (P < 0.011) discoloration than did steaks from the implanted/nonvitamin D3 supplemented animals. Loin steaks from nonimplanted/vitamin D3 fed steers were intermediate and not statistically different in muscle discoloration on d 1 of display from the other treatment combinations. The discoloration differences found on d 1 of display did not hold true through the remaining portion of the display period. |
Implications |
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TopAbstractIntroductionMaterials and MethodsResults and DiscussionImplicationsLiterature Cited |
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Footnotes |
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2 Current address: P.O. Box 830908, Lincoln, NE 68583-0908.
Received for publication October 30, 2001. Accepted for publication August 8, 2002.
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Literature Cited |
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TopAbstractIntroductionMaterials and MethodsResults and DiscussionImplicationsLiterature Cited |
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