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Pre-Harvest Cattle ManagementPractices for Enhancing

Beef TendernessEXECUTIVE SUMMARY

Pre-Harvest Cattle ManagementPractices for Enhancing

Beef TendernessPrepared for the National Cattlemen’s Beef Association

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Pre-Harvest Cattle Management Practices for Enhancing Beef Tenderness

By J. D. TatumDepartment of Animal SciencesColorado State UniversityMarch 2006

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“The end-product is taste…

People will pay more for greater satisfaction, and

taste is their measure of satisfaction in food…

Meat producers who are customer-driven must

seek to influence the factors that affect taste all

the way from the field to the table.”

(Feargal Quinn, 1999)1

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MANAGEMENTOF

BEEF TENDERNESSIN

COORDINATEDBEEF

SYSTEMS�PPre-harvest management of

beef tenderness has becomean important topic in today’scattle industry due to the factthat tenderness is the primarydeterminant of eating satisfac-tion among beef consumers2

and because structural changesin the beef industry3 haveresulted in greater verticalcoordination of production,processing, and marketingactivities, making it feasible to manage product attributesalong the entire beef chain.Over the past several years,beef producers have workeddiligently to identify primarydrivers of consumer demandand to become more responsiveto consumer needs by improv-ing the quality, safety and

convenience of their products.Cattle producers who operatesuccessfully in today’s verti-cally coordinated businessstructures posses a heightenedawareness of consumers’ preferences and embrace production goals that are moreclearly focused on satisfyingthe end-users of their products.As Boehlje (1995) observed:

“The produce-and-then-sellmentality of the commodity

business is being replaced by thestrategy of first asking

consumers what they want asattributes in their food products

and then creating or manufacturing those attributes

in the products.” 4

The basic tenet of Total QualityManagement(TQM) is toimprove the pro-duction system inorder to preventproduct defects,rather thaninspecting finished productsand, then, removingthose that do notconform to qualityspecifications.

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“Tenderness management systems” (based on applicationof TQM principles) involvecontrol and verification of specific processes in the production chain that impacttenderness, and may be utilizedto differentiate beef productson the basis of palatability performance, with the ultimate goal of adding value to cattle. A growing body ofscientific evidence suggests thatseveral different pre-harvestfactors (both genetic and non-genetic) influence the eatingqualities of beef and can bemanaged systematically toenhance quality characteristicsof the end product.5 Key elementsof effective pre-harvest beeftenderness management systems(i.e., process control points)include: • control of breed/genetic

inputs,

• use of feeding systems that enhance product quality,

• judicious application of growth enhancement technologies, and

• adherence to best management practices to avoid quality and tenderness problems associated with the effects of morbidity, pre-harvest stress, administration of animal health products, and hormonal status of the animal.

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MANAGINGGENETICINPUTS� OOptimizing cowherd produc-

tivity across the broad rangeof beef production environmentsin the U.S. requires the use of diverse biological types ofcattle that differ with respectto size, milk production,growth and maturing rates,and adaptability to regionaldifferences in feed resourcesand climatic conditions. The

high degree of genetic diversityamong and within the variousbreeds and biological types ofcattle currently utilized inU.S. beef production systems,while advantageous from aproduction standpoint, repre-sents an important source ofvariation in beef tenderness.Correspondingly, the selectiveuse of breeds and selection of

TABLE 1. Comparison of carcass quality and beef tenderness characteristics for eight of the most widely used cattle breeds in U.S. production systems

Age-constant meansa

Breed Type Marbling score % Choice & higher Shear force, kgAngus Bos taurus/British SM88 88 4.0Hereford Bos taurus/British SM26 65 4.1Red Angus Bos taurus/British SM90 90 4.1Charolais Bos taurus/Continental SM17 62 4.3Gelbvieh Bos taurus/Continental SM06 58 4.5Limousin Bos taurus/Continental SM04 57 4.3Simmental Bos taurus/Continental SM27 66 4.3Brahman Bos indicus/Zebu SL73 30 5.9aSource: Wheeler et al., 2001, 2005. SM = Small, SL = Slight. Lower shear force values are indicative of greater tenderness

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specific genetic lines withinbreeds, both warrant consid-eration as pre-harvestprocess control points formanaging beef tenderness.

Balancing Strengths of Diverse Breeds.

Carcass quality and beef tenderness characteristics of eight of the most widely utilized beef cattle breeds in today’s U.S. production systems are compared inTable 1.6, 7 The three Britishbreeds (Angus, Hereford,and Red Angus) listed inTable 1 represent the mostfrequently utilized maternal-type breeds in U.S. commercialbeef herds and have a long-standing reputation for producing high-quality, tender beef. Data in Table 1suggest that all three Britishbreeds produce beef withsuperior tenderness, whilethe Angus and Red Angusbreeds excel in both tenderness and carcass quality grade performance. The four most prevalentContinental breeds(Charolais, Gelbvieh,Limousin, and Simmental)are used extensively in cross-breeding systems, not onlyfor their positive contribu-tions to growth performanceand red meat yield, but also,

in some cases, to enhancematernal performance. Beefproduced by the Continentalbreeds is very acceptable intenderness, but ranks slightlylower with respect to averagetenderness (i.e., slightlyhigher shear force) than beeffrom British breeds of cattle(Table 1).

While all of the Bos taurusbreeds listed in Table 1 (andseveral others not listedhere) merit consideration for use in consumer-drivenbreeding systems, producerswhose goals are focusedspecifically on production of high-quality, tender beefshould emphasize use ofbreeds with lower meanshear force values and highermean marbling scores.Crossbreeding systems thatresult in feeder cattle with 50 to 75% British and 25%to 50% Continental breedinfluence are recommendedfor balancing the growthperformance and carcassyield advantages of theContinental breeds with the maternal performanceand beef quality advantagesof the British breeds.8

Increasing numbers of commercial cattlemen areusing hybrids (e.g., Balancer,LimFlex, SimAngus, etc.) orcomposites in their breeding

programs to attain thedesired mix of British and Continental breeding,while capitalizing on performance advantagesstemming from heterosis and breed complimentarity.

The Brahman breed (a Bosindicus or Zebu breed) is themost widely utilized tropicallyadapted cattle breed in theU.S., and offers distinct production advantages forcattle producers in the southern region of the country.Among the various cattlebreeds commonly used inU.S. production systems, themost pronounced between-breed tenderness differencesexist between Bos indicus andBos taurus breeds (Table 1).Cattle of the various Bos indicusbreeds consistently havebeen shown to produce beefthat is less tender than beeffrom Bos taurus breeds of cattle.6, 9,10 Correspondingly,tenderness tends to decrease(i.e., shear force increases)almost linearly (see Figure1) as percentage of Bos indicus breeding increases.11, 12

An effective strategy forenhancing tenderness via the selective use of breeds isto moderate the percentageof Bos indicus breeding inmarket steers and heifers.

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Research suggests that lim-iting Bos indicus inheritanceto 3/8 (37.5%) or less iseffective for reducing theincidence of tendernessproblems.13, 14 For producerswho operate in subtropicalor tropical environments,substituting a tropicallyadapted non-Zebu breed(e.g., Romosinuano,Senepol, Tuli) for the Bosindicus breed component inthe development of heat-tolerant composites also maybe a viable strategy for man-aging tenderness.15 When itis not possible to documentactual percentages of Bosindicus inheritance amonggroups of cattle, live animaland (or) carcass specifica-tions based on phenotypecan assist in the assuranceof acceptable tenderness.16

For example, several brandedbeef programs currently

include carcass specificationsthat utilize hump height as a phenotypic indicator ofBos indicus breeding.

Within-Breed Selection toImprove Tenderness.Heritability estimates from anumber of studies suggestthat tenderness is moderatelyheritable (h2 = 0.24 to 0.53)in Bos taurus and Bos taurusx Bos indicus cattle popula-tions,6, 10, 15, 17-19 but lowlyheritable (h2 = 0.14 to 0.17)in pure strains of Brahmancattle.20, 21 Seedstock andcommercial cattle breedershave relied on traditionalmethods, such as progenytesting, to obtain beef tenderness information for selection purposes.Consequently, the time andexpense required to changetenderness via traditionalselection methods have been

major impediments to genetic improvement of beef tenderness.

For beef programs thatinvolve collection of tender-ness data for sire-identifiedprogeny groups, preferentialuse of specific sires whoseprogeny produce beef withsuperior tenderness (i.e.,selection of “tender” sires) is fundamentally effectivefor enhancing tenderness.5

To facilitate selection ofsires for long-term geneticimprovement in tenderness,several breeds are developingand reporting ExpectedProgeny Differences (EPD)for tenderness.22 In addition,there is a growing numberof commercially availableDNA markers for genesassociated with differencesin beef tenderness and somebreeders have begun DNAtesting of seedstock, awaitingfurther validation and evaluation of the usefulnessof marker-assisted selectionfor improving beef tender-ness. Gene markers thatprove effective for identifyinggenetic differences in tenderness among breedingcattle offer tremendouspotential for augmentingtraditional methods of selection for improved beeftenderness.23

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Figure 1.Percentage of Bos indicus breeding and longissimus shear force

(Source: Johnson et al., 1990)

0 25 50 75% Bos indicus breeding

6.0

5.5

5.0

4.5

4.0

3.5

3.0

Shea

r for

ce ,

kg

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GGrain Feeding. Cattle feedingsystems in the U.S. aredesigned specifically to producegrain-fed beef, which isdemanded by most mainstreammarkets (both domestic andexport). Studies comparingquality characteristics of forage-fed and grain-fed beef havedemonstrated that grain feedingimproves several carcassindicators of beef quality.Grain-fed cattle produce carcasses with brighter-colored,finer-textured lean,24 whiterfat,25 and more marbling,26 allof which enhance acceptabilityof fresh retail beef.27 In addition,most comparisons of forage-fedand grain-fed beef suggest thatgrain feeding improves tender-ness and flavor.28 For producersinterested in labeling and merchandising beef productsas “Grain Fed,” the USDA hasdefined a grain diet as “anycereal plant product that meetsor exceeds 60 Mega caloriesNet Energy for gain (NEg) per100 pounds dry matter” andhas specified that, for cattle tomeet USDA process verifica-tion standards for “Grain Fed,”average grain consumptionmust equal 50% or more of theration, with a minimum of 100days on feed.29

Days On Feed. Though only asmall number of cattle targetedfor U.S. beef markets are forage-finished, a great number of

young, stocker cattle are back-grounded (grown) on variousforages (grazed or harvested)for several months before receivinghigh-concentrate, finishingdiets.30 Cattle that are grownon relatively low-energy, foragediets must be fed a high-concen-trate diet for a sufficient periodof time in order to develop thecarcass quality characteristicsand beef palatability attributesnormally associated with thoseof grain-fed beef. Researchconducted to characterize therelationship between time-on-feed(the number of days cattle arefed a high-concentrate finishingdiet) and beef palatabilityattributes has shown that mostimprovements in both tender-ness and flavor occur duringthe early portion of the finishingperiod (before 112 days on feed),31-34 and that finishing periods

longer than approximately 100days seem to provide little addi-tional improvement in eithertenderness (see Figure 2) orflavor.31-37 Feeding yearling cattle a high-concentrate, finish-ing diet for periods longer than180 days has been shown to bedetrimental to tenderness dueto increased maturity.38

Correspondingly, to minimizethe incidence of toughnessproblems stemming fromadvanced maturity, grain-fin-ished cattle should be harvestedat young ages – preferably lessthan 24 months of age.39

Figure 2.Relationship between days on feed and longissimus shear force (Source: May et al., 1992)

0 28 56 84 112 140 168 196Days on feed

9876543210

Shea

r for

ce ,

kg

FEEDINGSYSTEMS�

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USE OFGROWTH

ENHANCEMENTTECHNOLOGIES� CConventional beef produc-

tion systems in the U.S.involve the use of anabolicimplants during one ormore phases of productionprior to harvest. Implants,administered to growingand finishing cattle, signifi-cantly increase net returnsby increasing both rate and efficiency of weightgain, primarily by enhanc-ing protein accretion.Implanting improves dailygain by approximately 6%in suckling calves,40 12 to16% in stocker cattle,41 and15 to 25% in feedlot cattle.42

Moreover, implanting cattleduring the pre-weaningand stocker phases of production has been shown to have little impact on subsequent growth perform-ance during finishing.41, 43

Duckett and Andrae(2001) estimated that thecumulative effects ofimplants used in each suc-cessive phase of production(suckling, stocker, andfeedlot) would increase liveweight by approximately125 pounds and add morethan $90 to the value ofeach animal.44 Because theeffects of implanting are soeffective for enhancingprofitability in all stages ofproduction, very few cattle

reach market weight withouthaving received at least oneimplant at some point inthe production chain, andmany cattle receive multiplelifetime implants as theyproceed through variousstages of production.45

The obvious exceptionwould be cattle that areproduced for one of thegrowing number of naturalbeef programs.

Pre-Finishing Implants.Only a few studies haveinvestigated the effects of pre-finishing implants on product tenderness.Existing evidence, thoughlimited, suggests that thelow-potency implants commonly used in sucklingcalves and stocker cattle do not adversely affect beef tenderness;46, 47 however,repetitive use of estrogenicimplants has been shown to increase carcassmaturity46-49 and use ofmultiple lifetime implantsmay reduce marblingscores.48 Correspondingly,Platter et al. (2003) advocated limited use ofpre-finishing implants incoordinated beef systemsto minimize the risk ofdetrimental effects on beefquality.47

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Finishing Implants.Results of a USDA survey of the U.S. feedlotindustry50 suggest thatover 97% of all feedlotcattle receive one or moreimplants during finishing.The number of implantsadministered to feedlotcattle depends upon theprojected duration of the finishing period.Heavyweight feeder

cattle (> 750 pounds forsteers and > 700 poundsfor heifers) fed fewer than130 days typically receiveonly one finishing implant.Lighter-weight cattlerequiring finishing periodsof 130 days or longer usually receive two sequen-tial finishing implants, withthe terminal implantadministered 70 to 120days before harvest.

Very lightweight calves (< 450 pounds), projectedto require 230 or moredays of finishing, sometimesreceive three implants during finishing.51 However,based on industry surveyresults, only about 6% ofthe cattle entering U.S.feedlots weighing less than700 pounds would receivemore than two implants.50

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Implant products commonlyadministered to feedlot cattle during finishing are listedin Table 2. Heavy feeder cattle,scheduled to receive a singlefinishing implant, frequentlyare implanted with one of several relatively high-potencycombination implants that containboth estrogen (E2) and trenbolone acetate (TBA).Single-implant programs forsteers often involve the use ofComponent TE-S, Revalor-S,Component TE-200, Revalor-200, or Synovex Plus, whereasheifers receiving a single-implant frequently would beimplanted with ComponentTE-H, Revalor-H, Revalor-200, or Synovex Plus. Steersscheduled to receive two successive finishing implants(implant/re-implant) typicallyreceive an estrogenic implant(e.g., Ralgro, Component E-S, Synovex-S) or a low-dose combination implant (e.g., Component TE-IS,Revalor-IS, Synovex Choice)initially, followed by one of thehigher-potency combinationproducts (listed previously) asthe terminal implant. Heifersimplanted twice typicallyreceive a low-dose combinationimplant (e.g., Component E-H, Synovex-H, ComponentTE-IH, Revalor-IH) initially,followed by a higher-potencycombination terminal implant.

Table 2.Commonly used cattle finshing implantsa

Trade name Approved use Estrogen, mg Androgen, mg Estimated effectiveness, d

Estrogenic (E):

Component E-S S 14 E2 120Synovex-S S 14 E2 120Compudose S/H 25.7 E2 175Duralease S/H 14 E2 175Encore S/H 43.9 E2 350Ralgro Magnum S 72 Zeranol 90

(22-26 E2 activity)

Ralgro S/H 36 Zeranol 70(11-13 E2 activity)

Androgenic (A):

Component T-S S 140 TBA 105Component T-H H 200 TBA 105Finaplix-H H 200 TBA 105

Combination (E+A):

Component TE-IS S 16 E2 80 TBA 110Revalor-IS S 16 E2 80 TBA 110Synovex Choice S 10 E2 100 TBA 120Component TE-S S 24 E2 120 TBA 120Revalor-S S 24 E2 120 TBA 120Component TE-IH H 8 E2 80 TBA 110Revalor-IH H 8 E2 80 TBA 110Component TE-H H 14 E2 140 TBA 120Revalor-H H 14 E2 140 TBA 120Component E-Hb H 14 E2 200 TP 120Synovex-Hb H 14 E2 200 TP 120Component TE-200 S 20 E2 200 TBA 130Revalor-200 S/H 20 E2 200 TBA 130Synovex Plus S/H 20 E2 200 TBA 130

a Adapted from: Campbell et al. (2005), CattleNetwork.com.b Contains testosterone propionate (TP).

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More aggressive two-implantprograms, involving thesequential use of two high-potency combinationimplants, are sometimes used to maximize growthperformance,51 whereas cattle feeders who are mostinterested in enhancing quality grade performanceoften choose to use animplant/re-implant programthat involves the use of two estrogenic or twosequential low-dose combi-nation implants.

Recent studies investigatingthe effects of finishingimplants on beef qualitycharacteristics suggest thatcertain implant programs

may adversely affect producttenderness47, 52, 53 and consumeracceptability.47, 54 An analysisof published data from tenstudies47, 53-61 was conductedfor this review and is summarized in Figure 3 topermit comparison of severalof the more commonly used implant programs forfinishing steers (too fewstudies involving heifers havebeen conducted to providemeaningful comparisons or recommendations).Values presented in Figure 3 are expressed as standard-ized mean differences inshear force between implanttreatments and non-implantedcontrols and show the

relative effect of each implantprogram on beef tenderness.In the context of this analysis, values of 0.20 to 0.29 represent “small” increases in shear force, whereas valuesof 0.43 to 0.53 reflect “moderate” increases in shearforce. These results demon-strate that careful use of finishing implants is essentialfor effective tendernessassurance, and suggest thatimplant programs for steersfeaturing a single mid-dosecombination implant (24 mg E2, 120 mg TBA), twosuccessive estrogenicimplants (14 mg E2/14 mgE2), or an estrogenic implant(36 mg Zeranol or 14 mg E2)

Figure 3.Effects of steer finishing implant programs on Warner-Bratzler shear force of the longissimius muscle

(treatment effects are expressed as standardized mean differences from a non-implanted control)

RS/RS 0.53

SP 0.45

SS or RA/SP 0.43

RS 0.29

SS or RA/RS 0.25

SS/SS 0.20

0.00 0.10 0.20 0.30 0.40 0.50 0.60

Legend: RA = Ralgro, RS = Revalor-S; SP = Synovex Plus, SS = Synovex-S; “/” denotes initial implant/terminal implant

Impl

ant p

rogr

am

Standardized WBSF difference from non-implanted control

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followed by a mid-dose combination implant (24 mgE2, 120 mg TBA) may beused without materiallyreducing tenderness (Figure3). However, if the cattlefeeder’s goal is to minimizebeef toughness problems,more aggressive implantprograms, such as thoseinvolving a single high-dosage combination implant(20 mg E2, 200 mg TBA), animplant/re-implant sequenceincluding an estrogenicimplant (36 mg Zeranol or14 mg E2) followed by ahigh-dosage combinationimplant (20 mg E2, 200 mgTBA), or two successivemid-dose combinationimplants (24 mg E2, 120 mgTBA/24 mg E2, 120 mgTBA) should be avoided(Figure 3).

Feed Additives.Supplementing finishingdiets for heifers withmelengestrol acetate (MGA)is a common practice in the

commercial feeding industry.Melengestrol acetate is anorally active progestin that,when included in the diets of heifers, suppresses estrusand improves growth performance.62 Dietary supplementation with MGAincreases circulating levelsof estrogen in heifers, similarto the effect of implantingwith a mild estrogenicimplant. Correspondingly,MGA is particularly effective for enhancinggrowth performance of feedlot heifers implantedwith androgenic implants.Nichols et al. (1996) reporteddata suggesting that includingMGA in diets of feedlotheifers had no effect onWBS or trained sensorypanel ratings for tenderness.63

Heifers supplemented withMGA normally will showsigns of estrus within 2 to 7days of MGA withdrawal.The increased physical activity and stress associatedwith behavioral estrus inheifers, following MGAwithdrawal, can result in anabnormally high incidenceof dark cutting carcasses.Consequently, heifers shouldnot be removed from MGA-supplemented diets for periodslonger than 24 hours priorto harvest. In the U.S.,

MGA has no withdrawalrequirement and may be feduntil the time of shipmentfor subsequent harvest.

Optaflexx (the trade namefor ractopamine hydrochlo-ride) is a relatively new cattlefeed ingredient designed toincrease live weight gain,improve feed efficiency, andincrease carcass yields oflean beef. Ractopaminehydrochloride is a beta-adrenergic agonist that ismixed into cattle finishingdiets and provided to feedlotsteers and heifers during thefinal 28 to 42 days beforeharvest. Research trialshave shown that Optaflexx,when fed to steers at therecommended dosage of 200mg/hd/d for the last 28 daysof the finishing period,increases average daily gainsby approximately 20% andimproves feed efficiency(F/G) by almost 16%. Inaddition, Optaflexx supple-mentation (200 mg/hd/d)increases carcass weight,ribeye area, and carcassleanness (measured as %protein in the carcass), withlittle effect on marblingscore, quality grade, carcassmaturity, lean color, the incidence of “dark cutting”carcasses, or beef tender-ness.64, 65

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�HADDITIONAL BEST

MANAGEMENTPRACTICES FORTENDERNESSASSURANCE

Health Management andHusbandry. Differences in costs associated withmorbidity are the mostimportant source of varia-tion in profitability amonggroups of feedlot cattle,66

which underscores the fundamental importance of effective cattle health-management programs.Morbidity during the finishing period (most frequently associated withbovine respiratory diseasecomplex – BRD) depressesgrowth performance of finishing cattle, resulting inlighter carcass weights andlower marbling scores.67, 68

In addition, Gardner et al.(1999) reported that cattlewith respiratory tractlesions at the time of har-vest produced tougherlongissimus steaks (aged 7 days) than did cattlewithout lung lesions.67

Correspondingly, effectivetenderness managementdemands implementation of effective health manage-ment programs at all pointsin the beef chain.

Administration of animalhealth products via intramuscular(IM) injectioncan cause development of a lesion near the site of injection, which influences

tenderness of the surroundingmuscle. An intramuscularinjection causes trauma to the muscle at, andaround, the injection site.Subsequent wound healinginvolves infiltration of connective tissue – whichcauses significant tougheningof the surrounding muscle tissue – up to three inchesfrom the center of thelesion.69 Strict adherence toBQA guidelines for use ofanimal health products isadvocated to avoid tender-ness problems associatedwith IM injections.

Timely application of routinemanagement practices,such as castration of malecalves, also can reduce variation in beef tenderness.To avoid sex-related beeftenderness problems, bullcalves destined to becomefeeders should be castratedbefore they begin to developthe secondary sex charac-teristics of mature intactmales.70 The NCBA BeefPalatability Task Force recommendations issued in 1996 encouraged U.S.cattlemen to castrate bullcalves prior to 7 months of age.71

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Avoiding Pre-SlaughterStress.Relationships between pre-harvest stress and meatquality characteristics havebeen recognized for manyyears. Pre-harvest stress,either acute or prolonged,depletes muscle glycogenstores, resulting in the production of beef with anabnormally high final musclepH and a characteristicallydark lean color (referred toas “dark cutting” beef).72, 73

Pre-harvest conditions thatcause any form of physicalor psychological stressamong cattle can result inmuscle glycogen depletionand increase the incidenceof dark cutting beef.Common pre-harvest stressors in cattle include: a) aggressive handling,

excitement, or physical exertion of cattle before, during, or following transport to the processing plant;

b) long transit periods and (or) schedule delays preventing prompt unloading of cattle transported to processing plants;

c) mixing of cattle from different sources before harvest, prompting physical activity as animals re-establish an order of social dominancewithin the mixed group;

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d) extremes in climatic conditions, including both extremely hot weatherand cold, wet weather;

e) extended fasting periods or prolonged feeding of very low-energy diets before harvest; and

f) females exhibiting behav-ioral estrus near the time of harvest.

Carcasses produced by cattle subjected to pre-har-vest stress exhibit varyingdegrees of the dark cuttingcondition, depending uponthe extent of ante-mortemglycogen depletion and thefinal pH of the carcassmusculature. Final musclepH within a range of 5.4 to5.7 is considered normal forbeef. As muscle pHincreases above 5.7, leancolor becomes progressivelydarker. Beef carcasses withslightly higher-than-normalfinal muscle pH values,ranging from 5.8 to 6.2,exhibit a lean color that isonly slightly dark; however,

a number of studies haveshown that muscle pH values within this range areassociated with a compara-tively high frequency ofmeat toughness problems.74, 75

Cattle differ in behaviorand temperament and,therefore, react differentlywhen subjected to variouspre-harvest stressors.Voisinet et al. (1997) deter-mined that temperamentalcattle produced carcasseswith a very high (25%)incidence of a slightly darklean color and longissimussteaks that were significantlytougher when comparedwith carcasses and steaksproduced by calmer cattle.76

More recently, Australianscientists have established agenetic relationshipbetween “flight time” andbeef tenderness. “Flighttime” is an electronic measurement of the timerequired for an animal totravel a specified distance

(approximately 2 meters)after it leaves a squeeze-chute, and is related to theanimal’s temperament(more excitable animalshave faster flight times).Studies conducted by scien-tists at the CooperativeResearch Centre for Cattleand Beef Quality haveshown that “flight time” is moderately to highly heritable and has a relativelystrong genetic correlation (r = -0.53) with longissimusshear force. Interestingly,phenotypic correlationsbetween “flight time” andmeasures of tendernesswere found to be very low,which led the researchersto conclude that “best practice” handling mightovercome tenderness problems associated withpoor temperament and pre-harvest stress.77 Adoptingmanagement practices thatreduce handling and envi-ronmental stress and pref-erential selection of cattlewith calm temperamentsare essential elements ofeffective beef quality man-agement systems. Meat &Livestock Australia (2000)offers cattle producers avery useful set of practicalguidelines for avoiding beefquality problems caused bypre-harvest stress.78

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THE IMPORTANCE OFBEEF PRODUCERS’

EFFORTS TO MANAGEBEEF TENDERNESS

DDelivering a quality eatingexperience is essential to thecontinued success of the beefindustry’s efforts to buildconsumer demand for beefproducts.79 Consumer surveyresults suggest that eatingquality (defined by mostconsumers simply as “taste”)is a primary driver of foodpurchase decisions across avariety of product categories80

and experimental marketresearch has established adirect link between the eating qualities (tendernessand flavor) of beef and actual purchase behavior ofbeef consumers.81-84 Thesefindings are significant to thebeef industry because theyprovide compelling evidence,suggesting that efforts toimprove the eating qualitiesof beef, if successful, will notonly increase the likelihoodthat a consumer will purchasea beef product, but also can increase the prices thatshoppers are willing to pay

for beef. Beef consumersassociate eating satisfactionwith product value andmany are willing to pay pre-mium prices for beef with the level of tendernessor the flavor characteristicsthey prefer.81-84

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Barkema, A. and M. Drabenstott.1996. Consolidation and Change inHeartland Agriculture. Proceedings:Economic Forces Shaping the RuralHeartland. Federal Reserve Bank ofKansas City.

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Tatum, J.D., K.E. Belk, M.H.George, and G.C. Smith. 1999.Identification of quality managementpractices to reduce the incidence ofretail beef tenderness problems:Development and evaluation of a pro-totype quality system to produce ten-der beef. J. Anim. Sci. 77: 2112-2118.

Wheeler, T.L., L.V. Cundiff, S.D.Shackelford, and M. Koohmaraie.2001. Characterization of biologicaltypes of cattle (Cycle V): Carcasstraits and longissimus palatability. J.Anim. Sci. 79:1209-1222.

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Ritchie, H.D. 2006. Connecting thecowherd to carcass traits. GelbviehWorld, Vol. 20, No. 7:50-51.

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Boleman, S.J., S.L. Boleman, R.K.Miller, J.F. Taylor, H.R. Cross, T.L.Wheeler, M. Koohmaraie, S.D.Shackelford, M.F. Miller, R.L. West,D.D. Johnson, and J.W. Savell.1997. Consumer evaluation of beef ofknown categories of tenderness. J.Anim. Sci. 75:1521-1524.

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Umberger, W.J., D.M. Feuz, C.R.Calkins, and K.M. Killinger. 2000.Consumer preference and willingnessto pay for flavor in beef steaks. Paperpresented at the 2000 IAMAAgribusiness Forum, Chicago, IL.

Platter, W.J., J.D. Tatum, K.E. Belk,S.R. Koontz, P.L. Chapman, and G.C.Smith. 2005. Effects of marbling andshear force on consumers’ willing-ness-to-pay for beef strip loin steaks.J. Anim. Sci. 83:890-899.

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