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J. Anim. Sci. 2003. 81:3052-3056
© 2003 American Society of Animal Science

Effects of growth implants on consumer perceptions of meat tenderness in beef steers1

B. L. Barham2, J. C. Brooks2, J. R. Blanton, Jr.2, A. D. Herring3, M. A. Carr4, C. R. Kerth5 and M. F. Miller6

Department of Animal and Food Sciences, Texas Tech University, Lubbock 79409-2162


   Abstract
Top
 Abstract
Introduction
 Materials and Methods
 Results and Discussion
 Implications
 Literature Cited
 
Anabolic steroid implants are routinely used to increase growth performance and profitability; however, there are concerns that the use of implants, particularly those containing trenbolone acetate, may have detrimental effects on carcass quality and beef tenderness. Thus, the objectives of the current study were to determine the effects of various commonly used implant regimens on shear force values, sensory properties, and consumer satisfaction of beef top loin steaks from cattle of Bos indicus influence. Cattle were supplied by producers that agreed to provide sire and dam information in exchange for carcass and sensory data. Steers (n = 2,748) were assigned randomly to one of three implant treatments (12/sire; four steers from each sire were placed into each treatment group): 1) unimplanted controls (n = 1,368); 2) Synovex-S followed by another Synovex-S (n = 660); or 3) Synovex-S followed by Revalor-S (n = 720). Steaks sampled after 3, 7, and 14 d of aging indicated that unimplanted cattle had lower (P < 0.05) Warner-Bratzler Shear force values than those from implanted animals. No differences (P > 0.05) in shear force values were found between the two treatments or the control groups for steaks sampled following a 21-d aging period. Steaks from implanted animals sampled after 3, 7, and 14 d aging were rated lower (P < 0.05) for initial and sustained trained sensory panel tenderness scores. Consumers failed to detect any differences in steak samples related to implant treatment after 7 and 14 d of aging. Consumer education level and family income did not affect overall acceptability (P > 0.10 and 0.18, respectively) or tenderness acceptability (P > 0.11 and 0.68, respectively); however, consumers with postgraduate degrees recorded lower (P < 0.05) overall quality, beef flavor, juiciness, and tenderness scores than consumers in all other education classifications. Additionally, family income had no effect on overall quality (P > 0.21), beef flavor (P > 0.28), juiciness (P > 0.58), or tenderness (P > 0.45) scores. Results indicate that using a moderate implant program in Bos indicus-influenced cattle has no detrimental effects on beef tenderness and consumer acceptability.

Key Words: Beef • Bos indicus • Growth Implants • Palatability • Tenderness


   Introduction
Top
 Abstract
 Introduction
Materials and Methods
 Results and Discussion
 Implications
 Literature Cited
 
Anabolic steroids have been widely used in the beef cattle industry for over 50 yr as feed additives and implants to increase growth performance and profitability. However, the use of implants, particularly those containing trenbolone acetate, may have detrimental effects on carcass quality and beef tenderness (Smith et al., 1992Go; Samber et al., 1996Go; Roeber et al., 2000Go). When trenbolone acetate and estrogenic implants are combined, they often have synergistic effects on growth (Apple et al., 1991Go; Bartle et al., 1992Go; Foutz et al., 1997Go). Platter et al. (2001)Go concluded that repeated implanting not only increased growth but also had detrimental effects on carcass quality, Warner-Bratzler shear force (WBSF) values, and consumer taste panel scores. These animals received up to five implants during the production chain, which is not a common practice currently being followed in the beef cattle feeding industry.

Miller et al. (2001)Go determined that 75% of consumers were willing to pay a premium for tender beef. Thus, tender carcasses could be worth up to $76 more than tough carcasses (Miller et al., 2001Go). Implant treatment can affect tenderness and, therefore, affect consumer satisfaction and carcass value. Given that a large portion of cattle fed in the United States are implanted, the objectives of the current study were to determine the effects that various commonly used implant regimens have on WBSF values, sensory properties, and consumer satisfaction of beef top loin steaks from cattle of Bos indicus influence of known genetic background and controlled sire-grouping.


   Materials and Methods
Top
 Abstract
 Introduction
 Materials and Methods
Results and Discussion
 Implications
 Literature Cited
 
Animals used in this study were 3/8 Bos indicus, 5/8 Bos taurus steers that were placed in the study by producers that agreed to provide sire and dam information on each steer in exchange for carcass and sensory data. In addition, producers agreed to supply at least 12 offspring/sire, and four offspring from each sire were allocated to each implant treatment. Before arrival at a commercial feed yard, producers agreed to supply individual identification, sire, and background of cattle being shipped. On arrival, animals received vaccinations against the major clostridial bacteria, and infectious bovine rhinotracheitis, parainfluenza-3, and bovine viral diarrhea. Also at this time, cattle were dewormed, individually tagged, individually weighed, and evaluated for breed-type, temperament, frame score, muscle score, and condition score. Using producer-supplied information, steers (n = 2,748) were randomly assigned to one of three implant treatments: 1) unimplanted (controls; n = 1,368); 2) implanted with Synovex-S (Fort Dodge Animal Health, Overland Park, KS) on d 0 followed by another Synovex-S implant on d 80 to 90 (SS; n = 660); or Synovex-S on d 0 followed by Revalor-S (Intervet, Millsboro, DE) implant on d 80 to 90 (SR; n = 720). When a producer supplied more than 12 offspring per sire, the additional offspring were placed in the control treatment (unimplanted). Animals in the study were fed for an average of 210 d.

Final weights were obtained from each animal approximately 5 h before slaughter at a commercial beef packing plant (Plainview, TX). Cattle were harvested when visually determined to have reached 1.0 cm of 12th-rib fat thickness by skilled live animal evaluators from Texas Tech University. Individual animal identification was maintained throughout the entire feeding and slaughter process. Following slaughter, carcasses were subjected to a 36-h spray chill at 2°C, and fabricated into primal and subprimal cuts according to Institutional Meat Purchasing Specifications (IMPS) for fresh beef (USDA, 1990Go). Boneless strip loins (IMPS #180) were obtained from one side of each carcass, vacuum-packaged, and transported in boxes under refrigeration to the Texas Tech University Meat Science Laboratory. All external fat was removed from the strip loin before slicing into 2.54-cm thick steaks. Steaks were vacuum-packaged and assigned randomly to one of four aging times (3, 7, 14, and 21 d). Following aging, steaks were frozen at -10°C until sensory evaluation.

Warner-Bratzler Shear and Trained Sensory Evaluation

Steaks for sensory and Warner-Bratzler shear force (WBSF) evaluations were thawed overnight at 2°C, and cooked to an internal temperature of 40°C, turned, and cooked to a final internal temperature of 71°C on a Farberware Open Hearth Broiler (Farberware Inc., Bronx, NY). Steaks designated for sensory panel evaluations were cut into 1 x 1 x 2.54-cm cubes and stored in warming pans until served to at least six trained sensory panelists. Samples were evaluated according to AMSA (1995) guidelines for initial juiciness, sustained juiciness, initial tenderness, sustained tenderness, flavor intensity, beef flavor, and overall mouth feel (8 = extremely juicy, extremely tender, extremely intense, extremely characteristic beef flavor, and extremely beef-like mouth feel to 1 = extremely dry, extremely tough, extremely bland, extremely uncharacteristic beef flavor, and extremely non-beef-like mouth feel), and off-flavor (5 = extremely off-flavor to 1 = none). All sensory panelists were trained according to the guidelines of Cross et al. (1978)Go.

Steaks for WBSF evaluations were placed on plastic trays, covered with polyvinyl chloride film, and chilled for 24 h at 2°C. Six 1.3-cm-diameter cores were removed from each steak parallel to the muscle fiber orientation and sheared once through the center with a Warner-Bratzler shear machine (G-R Elec. Mfg., Manhattan, KS). Shear force values for the six cores from each steak were averaged for statistical analysis.

Consumer Evaluations

Five diverse metropolitan areas (Baltimore, MD/Washington DC; Chicago, IL; Dallas/Fort Worth, TX; Los Angeles, CA; and Lubbock, TX) were selected to represent a wide range of consumer income, education, and ethnicity for each location. Corporate supermarket management evaluated the consumer statistics for each store in each metropolitan area in the chain and selected one high-, average-, and low-income store, which met the requirements for diverse education, ethnicity, and income level. Five trained research teams, consisting of six persons, traveled to the respective metropolitan areas to collect data during the same 10-d period. Steaks utilized for consumer evaluations were aged either 7 or 14 d, and were sorted into tenderness groups using shear force values outlined in Miller et al. (2001)Go. Teams cooked steaks from the same animal and aging treatment (as described previously for WBSF) at stores of similar income level in each city to a medium degree of doneness (71°C) at the same time on the same day to reduce the variation that could occur among locations. Three panels were served at each store, each panel containing one steak from each tenderness category with the same WBSF value (± 0.5 kg) between each replication. A total of 713 consumers (minimum of 15 consumers/panel, three panels/store, three stores/city) sampled two 1 x 1 x 2.54-cm cubes (six total cubes for each consumer) from each of three steaks representing tender, intermediate, and tough classifications (Miller et al., 2001Go). Consumers were asked to evaluate samples from each tenderness class (tender, intermediate, and tough). Each consumer evaluated the two cubes from each steak for overall and tenderness acceptability (acceptable or not acceptable). Additionally, consumers were asked to rate each steak for overall quality, beef flavor, juiciness, and tenderness (8 = like extremely, like extremely, extremely juicy, and extremely tender to 1 = dislike extremely, dislike extremely, extremely dry, and extremely tough). Consumers also were asked how much they would pay for the steak ($10.98, $14.28, or $17.14/kg) based on the average prices from all stores in all cities for Select, Choice, and Top Choice program prices during the time of the study. Each consumer was asked whether they would pay more than the current market price for a steak that was guaranteed tender. Consumers also were asked to estimate the number of meals in a 2-wk period that included beef (whether eaten at home or away from home) to determine whether they were light, moderate, or heavy beef users/eaters.

Statistical Analysis

Data were analyzed as repeated measures design using the mixed model procedures (PROC MIXED) of SAS (SAS Inst. Inc., Cary, NC). The fixed effects of implant treatment, breed, sire nested within breed, aging treatment, aging treatment x implant interaction, aging treatment x breed interaction, aging treatment x sire within breed interaction, and implant x sire interaction were included in the model for trained sensory and WBSF data. Animal nested within implant treatment, sire, and breed were included in the model as random effects to account for multiple measurements per animal. Date of slaughter was used as a covariate to account for time differences in the study. Consumer panel data were also analyzed utilizing the MIXED procedure. The model included fixed effects of implant treatment, aging treatment, sire of animal, city, store within city, degree of doneness, family income, and education level were included as fixed effects in the model. Date of slaughter was again included in the model as a covariate. Since several consumers sampled each steak, animal within sire was coded as a random effect to account for the correlation between samples from the same steak. Means were separated using the PDIFF option when a significant F-test was present using a predetermined significance level ({alpha} < 0.05).


   Results and Discussion
Top
 Abstract
 Introduction
 Materials and Methods
 Results and Discussion
Implications
 Literature Cited
 
Warner Bratzler Shear Force

Implant treatment did not (P > 0.27) impact WBSF values (see later Table 2Go). Gerkin et al. (1995)Go found that androgenic and combined implants had no effect on beef tenderness of strip loin steaks, which is supported by the results of this study. Belk and Savell (1992)Go also reported that implants containing trenbolone acetate and estradiol did not impact beef tenderness. However, Foutz et al. (1997)Go concluded that steers implanted with two trenbolone acetate implants were more likely to produce tough steaks than steers implanted with a single trenbolone acetate implant or two estradiol implants, which was noted in the results of this study, even though the difference was not significant.


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  		Table 2. Demographic information from consumers participating in consumer evaluation
 
As aging time increased, WBSF values were reduced (P < 0.0001; data not shown). The improvement of WBSF values corresponds with the normal proteolytic aging process and indicates that implanted animals do benefit from aging, as do unimplanted animals. The 1998 National Beef Tenderness Survey (Brooks et al., 2000Go) revealed that the average aging period of retail cuts sold in retail stores was 19 d. The 19-d aging period should be sufficient to reach tenderness levels for unimplanted and implanted animals that are acceptable for 93 to 98% of consumers (Miller et al., 2001Go). Miller et al. (2001)Go also indicated that consumer satisfaction would be 93% when WBSF values were between 3.0 and 4.3 kg. In the present study, all steaks were within this range and would be considered acceptable after only 7 d of aging. Only steaks from the control and SS treatment groups in this study would have been acceptable for a 100% guaranteed tender product (<3.0 kg WBSF) following a 21-d aging period.

Trained Sensory Panel

Aging steaks improved (P < 0.0001) initial and sustained tenderness scores (data not shown). Steers receiving implants had lower initial (P = 0.03) and sustained (P = 0.04) tenderness scores (Table 1Go). The results from the trained sensory panel indicate that implant treatment negatively impacted tenderness, whereas WBSF results did not indicate a difference. Implanting cattle did not (P > 0.37) affect flavor intensity scores during aging. Aging steaks longer increased (P < 0.0001) flavor intensity and beef flavor scores (data not shown). Implant treatment did not (P = 0.07) affect beef flavor scores. Overall mouth feel scores were not (P = 0.09) impacted by implant treatment for all aging periods; however, aging improved (P < 0.0001) overall mouth feel scores (data not shown).


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  		Table 1. Least squares means (± SE) for Warner-Bratzler shear force (WBSF) and trained sensory panel evaluations of strip steaks as affected by implant regimen
 
Consumer Evaluation

Demographic information for consumers participating in the study reveals that the consumers represented a wide range of consumer income, education, and ethnicity (Table 2Go). Consumers in the present study determined that implant treatment did not influence their evaluation of overall acceptability (P > 0.10), tenderness acceptability (P > 0.74), overall quality (P > 0.14), or flavor (P > 0.25) of steaks sampled (Table 3Go). Moreover, neither consumer ratings for juiciness (P > 0.17) nor tenderness (P > 0.27) were affected by implant regimen. Roeber et al. (2000)Go reported that implant strategy did impact consumer like/dislike and consumers rated steaks from implanted cattle higher than steaks from the other treatment groups.


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  		Table 3. Least squares means (± SE) for consumer sensory panel evaluation of strip steaks as affected by implant regimen
 
Consumer education levels and family income did not impact overall acceptability (P > 0.10 and 0.18, respectively) or tenderness acceptability (P > 0.11 and 0.68, respectively) (Table 4Go). However, education level influenced overall quality (P < 0.004), beef flavor (P < 0.005), juiciness (P < 0.003), and tenderness (P < 0.05) scores, having consumers with postgraduate degrees recording lower (P < 0.05) overall quality, beef flavor, juiciness, and tenderness scores than all other education classifications. On the other hand, family income had no impact on overall quality (P > 0.21), beef flavor (P > 0.28), juiciness (P > 0.58), or tenderness (P > 0.45) scores.


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  		Table 4. Least squares means (± SE) for consumer sensory attributes as affected by education level and family income
 

   Implications
Top
 Abstract
 Introduction
 Materials and Methods
 Results and Discussion
 Implications
Literature Cited
 
Previous research indicated that administration of growth implants may have detrimental effects on carcass quality and meat tenderness. Results from the present study reveal that a typical implant regimen affected sensory panel-evaluated beef tenderness, even though shear force values were similar among the implant treatments. More importantly, untrained consumers failed to detect any palatability differences among implant regimens after steaks were aged 7 and 14 d. This study indicates that using a moderate implant program (a two-implant regimen similar to the program used in this study) in Bos indicus-influenced cattle does not seem to negatively affect beef tenderness and consumer acceptability.


   Footnotes
 
1 Texas Tech University College of Agricultural Sciences and Natural Resources Manuscript No. T-5-434. Back

2 Dept. of Anim. and Food Sci., Texas Tech University. Back

3 Present address: Dept. of Anim. Sci., Texas A&M University, College Station 77843. Back

4 Present address: Dept. of Agric., Angelo State Univ., San Angelo, TX 76909. Back

5 Present address: Dept. of Anim. and Dairy Sci., Auburn Univ., Auburn, AL 36849. Back

6 Correspondence: P.O. Box 42162 (phone: 806-742-2804; fax: 806-742-0169; E-mail: mfmrraider{at}aol.com).

Received for publication July 25, 2002. Accepted for publication August 8, 2003.


   Literature Cited
Top
 Abstract
 Introduction
 Materials and Methods
 Results and Discussion
 Implications
 Literature Cited
 


Apple, J. K., M. E. Dikeman, D. D. Simms, and G. Kuhl. 1991. Effects of synthetic hormone implants, singularly or in combinations, on performance, carcass traits, and longissimus muscle palatability of Holstein steers. J. Anim. Sci. 69:4437–4448.[Abstract]

Bartle, S. J., R. L. Preston, R. E. Brown, and R. J. Grant. 1992. Trenbolone acetate/estradiol combinations in feedlot steers: Dose response and implant carrier effects. J. Anim. Sci. 70:1326–1332.[Abstract]

Belk, K. E., and J. W. Savell. 1992. Low quality grades-effects of implant on maturity, marbling and incidence of dark-cutting beef. Final Report of the National Beef Quality Audit 1991. National Cattlemen’s Beef Association, Englewood, CO.

Brooks, J. C., J. B. Belew, D. B. Griffin, B. L. Gwartney, D. S. Hale, W. R. Henning, D. D. Johnson, J. B. Morgan, F. C. Parish, Jr., J. O. Reagan, and J. W. Savell. 2000. National beef tenderness survey—1998. J. Anim. Sci. 78:1852–1860.[Abstract/Free Full Text]

Cross, H. R., R. Moen, and M. Stanfield. 1978. Training and testing of judges for sensory analysis of meat quality. Food Technol. 32:48–54.

Foutz, C. P., H. G. Dolezal, T. L. Gardner, D. R. Gill, J. L. Hensley, and J. B. Morgan. 1997. Anabolic implant effects on steer performance, carcass traits, subprimal yields, and longissimus dorsi muscle properties. J. Anim. Sci. 75:1256–1265.[Abstract/Free Full Text]

Gerkin, C. L., J. D. Tatum, J. B. Morgan, and G. C. Smith. 1995. Use of genetically identical (clone) steers to determine the effects of estrogenic and androgenic implants on beef quality and palatability characteristics. J. Anim. Sci. 73:3317–3324.[Abstract]

Miller, M. F., M. A. Carr, C. B. Ramsey, K. L. Crockett, and L. C. Hoover. 2001. Consumer thresholds for establishing the value of beef tenderness. J. Anim. Sci. 79:3062–3068.[Abstract/Free Full Text]

Platter, W. J, J. D. Tatum, K. E. Belk, T. E. Engle, J. A. Scanga, and G. C. Smith. 2001. Effects of repetitive use of growth promoting implants on beef carcass quality and consumer ratings of beef palatability. Final Report to National Cattlemen’s Beef Association, Denver, CO.

Roeber, D. L., R. C. Cannel, K. E. Belk, R. K. Miller, J. D. Tatum, and G. C. Smith. 2000. Implant strategies during feeding: Impact on carcass grades and consumer acceptability. J. Anim. Sci. 78:1867–1874.[Abstract/Free Full Text]

Samber, J. A., J. D. Tatum, M. I. Wray, W. T. Nichols, J. B. Morgan, and G. C. Smith. 1996. Implant program effects on performance and carcass quality of steer calves finished for 212 days. J. Anim. Sci. 74:1470–1476.[Abstract]

Smith, G. C., J. W. Savell, R. P. Clayton, T. G. Field, D. B. Griffin, D. S. Hale, M. F. Miller, T. H. Montgomery, J. B. Morgan, J. D. Tatum, and J. W. Wise. 1992. Improving the consistency and competitiveness of beef. The final report of the National Beef Quality Audit—1991. National Cattlemen’s Beef Association, Englewood, CO.

USDA. 1990. Institutional meat purchasing specifications for fresh beef. Agric. Marketing Serv., United States Department of Agriculture, Washington, DC.


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