Tenderness nd Intrmusulr Lipid of Most Mjor Musles from Bos Indius Cttle re Less thn Bos Turus Cttle C.M. Highfill, O.E. Font, M.E. Dikemn, nd D. H. Kropf Introdution In semitropil limtes in the United Sttes, reeds of ttle, primrily the Brhmn reed, re utilized in rossreeding progrms with Bos turus ttle to improve produtivity y inresing disese nd inset resistne, het tolerne, heterosis, nd dditive geneti vrition. Aout 25% of the U.S. eef popultion ontins some reeding. Numerous pulished reports show tht tenderness of rieye nd strip loin steks nd mrling re signifintly redued in strightred or rossred ttle ompred to most Bos turus reeds. One very lrge study reported tht heritility of tenderness nd mrling is round 0.4, mking it positive trit to try to improve through seletion. Only one pulished report hs ompred tenderness differenes etween nd Bos turus ttle for more thn the rieye nd strip loin (longissimus musle) nd tht study showed tht other musles were less tender for ttle. The ojetives of our study were: (1) to ompre rss trits etween Hereford x Angus rossred ttle with those ontining t lest 50% Brhmn nd Shiwl inheritne, nd (2) to vlidte Wrner-Brtzler sher fore of steks nd rosts nd proximte omposition of 10 different musles from these ttle. Experimentl Proedures Twenty Bos turus (Hereford x Angus) nd 20 (Brhmn or Shiwl sires mted to Hereford nd Angus ows), from Phse 5 of Cyle III of the Germ Plsm Evlution Projet onduted t the Romn L. Hrusk U.S. Met Animl Reserh Center (Cly Center, NE) were used. Clves were wened t pproximtely 200 dys of ge, preonditioned 30 dys, nd then fed orn nd orn silge diet until hrvest fter 169 dys on feed. Crsses were eletrilly stimulted nd hilled for 24 hours postmortem, ried t the 12th ri, nd evluted for rss trits y USDA grders. Right sides were frited to otin the following musles: suprspintus (SS), infrspintus (IF), nd trieps rhii (TB) from the huk; deep petorl (DP) from the risket; longissimus lumorum (LL), psos mjor (PM), nd gluteus medius (GM) from the loin; nd ieps femoris (BF), semitendinosus (ST), nd semimemrnosus (SM) from the round. One stek ws ut from eh musle, trimmed of visile onnetive tissue nd externl ft, nd used for ft, moisture, nd protein nlysis. Remining portions of the musles were vuum pkged, ged t 2ºF until 10 dys postmortem, then lst frozen t -40ºF for 8 hours. One 1-in. stek nd one rost were ut from eh frozen musle using power nd sw. The size for rosts ws dependent on the musle size. The SS, TB, DP, GM, nd BF were ut into 2-in.-thik rosts; the other musles were ut into 3-in.-thik rosts. Steks nd rosts were thwed t room temperture, held overnight in ooler, ooked in 325ºF Blodgett oven to n internl temperture of 150ºF, nd ooled for 2 hours t room temperture. Then 0.5-in.-dimeter ores were removed nd shered using 73
Wrner-Brtzler sher mhine. Dt were nlyzed sttistilly using SAS GLM proedures with proility level of P<0.05 for men seprtions. Results nd Disussion Crss trits re shown in Tle 1. Bos turus rsses were hevier, hd more ft over, nd hd lrger rieye res thn the rsses (P 0.05). In ddition, Bos turus rsses hd higher mrling sores (P=0.08). Yield grde tended to e higher for Bos turus ut it ws not sttistilly signifint. Intrmusulr ft perentge ws higher (P<0.05) in ll Bos turus musles ompred to musles (Tle 2). The IF musle hd the highest ft perentge; SM hd the lest intrmusulr ft. Differenes in intrmusulr ft perentges etween reeds were notiely greter for the LM nd BF musles thn for the other musles. The perent ooking loss for eh musle ws pooled for the reed types nd is shown in Tle 3. For ll musles exept TB, rosts took less time per oz to reh the finl end point temperture thn steks (dt not shown). Cooking losses were less (P<0.05) for TB, LL, nd SM steks thn for rosts, nd greter (P<0.05) for PM nd GM rosts thn steks. Cooking loss in steks nd rosts ws similr for SS, IF, DP, nd BF musles. The reltive surfe re exposed to het ws greter for steks, resulting in more intense evportion tht required more time per oz of rw weight to reh the finl internl temperture. Figures 1 through 9 show Wrner-Brtzler sher fore vlues for the 10 musles. In the forequrter, no reed or ut size min effet differenes ourred in Wrner-Brtzler sher fore for SS musles (Figure 1) ut reed ut size intertion (P<0.001) rose where rosts from Bos turus hd higher (P<0.05) Wrner-Brtzler sher fore vlues thn steks, wheres no differenes ourred mong steks nd rosts for. No reed differenes were found for IF (Figure 2), ut rosts for oth reed types were more tender thn steks. For the TB musle, oth steks nd rosts from Bos turus were more tender (P<0.05) thn those from (Figure 3). Figure 4 shows tht stek tenderness of DP ws not different etween reeds, ut rosts were less tender (P<0.05) thn rosts from Bos turus. Surprisingly, the DP ws more tender when ooked s steks thn s rosts (P<0.05). Figure 5 shows tht LL rosts nd steks hd higher (P<0.05) Wrner-Brtzler sher fore vlues thn Bos turus nd steks for oth reeds hd greter (P<0.05) Wrner-Brtzler sher fore vlues thn rosts. For the GM musle, Bos turus ws more tender (P<0.05) thn when ooked s steks nd rosts (Figure 6). The BF musle from ws less tender (P<0.05) thn Bos turus when ooked s steks ut not when ooked s rosts (Figure 7). When ST musles were ooked s steks, no reed differenes were oserved, ut ST rosts were less tender (P<0.05) thn Bos turus rosts (Figure 8). In ddition, ST rosts hd lower Wrner- Brtzler sher fore vlues thn steks. For SM steks nd rosts, musles were tougher (P<0.01) thn Bos turus musles (Figure 9). In ddition, SM musles were less tender (P<0.05) when ooked s rosts thn when ooked s steks. 74
Implitions When hndled to hve similr ge, kground, mngement, nd dys on feed, Bos turus rsses were expeted to e hevier, hve more ft over, hve lrger rieye res, higher mrling sores, nd greter intrmusulr ft perentges for ll 10 musles thn rsses. Furthermore, musles ooked s rosts were expeted to ook fster per unit weight thn steks. From the forequrter, tenderness of the SP nd IF musles were not expeted to differ due to reed or ut size. However, TB musles were expeted to e less tender thn those from Bos turus. Bos turus LL, GM, nd SM musles ooked s steks were expeted to e more tender thn those from, nd Bos turus LL, GM, ST nd SM musles ooked s rosts were expeted to e more tender thn those from. Overll, 7 of the 10 musles evluted were more tender from Bos turus when ooked s steks, rosts, or oth ut sizes. Tle 1. Crss trits for nd Bos turus heifers Men P-vlue Trits Bos turus Breed Hot rss weight, l 512.79 572.32 0.05 Mturity 53 55 0.47 Mrling 386 434 0.08 Ft Thikness, in. 0.35 0.47 0.01 Adjusted ft, in. 0.31 0.43 0.02 Riye re, in. 2 10.12 11.11 0.05 Kidney, pelvi, nd hert ft, % 2.5 2.8 0.13 Yield grde 2.57 2.86 0.2 All rsses were A mturity; numer refers to perentge within A mturity. 386 = Slight 86, 434 = Smll 34 Tle 2. Men perentges of intrmusulr ft y musle nd reed Intrmusulr ft, % Musle Bos turus Suprspintus 2.13 g 2.82 g Infrspintus 6.17 7.80 Trieps rhii 3.25 f 3.48 f Deep petorl 3.22 ef 4.13 ef Longissimus lumorum 3.79 d 5.75 d Psos mjor 5.33 6.46 Gluteus medius 3.94 de 5 de Bieps femoris 3.61 d 5.67 d Semitendinosus 4.49 5.76 Semimemrnosus 1.33 h 1.68 h defgh Mens within olumn lking ommon supersript letter differ (P<0.05). Ft perentges in ll musles were higher for the Bos turus ttle (P=0.001). 75
Tle 3. Lest squres mens for ooking loss, % Rost Stek Suprspintus 31.59 30.55 Infrspintus 28.99 27 Trieps rhii 28.04 25.42 Deep petorl 25.64 24.62 Longissimus lumorum 28.83 23.56 Psos mjor 28.64 30.03 Gluteus medius 27.69 29.89 Bieps femoris 28.47 28.06 Semitendinosus N/A N/A Semimemrnosus 34.80 29.49 Mens ompring ooking losses within eh musle lking ommon supersript differ (P<0.05). Bos turus Pek sher fore, l Stek P=0.18 Rost P=0.16 Breed ut size intertion P=0.001 Figure 1. Pek fore y reed nd ut size in Suprspintus musles. 76
Bos turus Pek sher fore, l Stek P=0.65 P=0.001 Rost P=0.07 Figure 2. Pek fore y reed nd ut size in Infrspintus musles. Bos turus Pek sher fore, l Stek P=0.04 Rost P=0.01 Breed ut size intertion P=0.85 Figure 3. Pek fore y reed nd ut size in Trieps rhii musles. 77
Bos turus Pek sher fore, l Stek P=0.97 Rost P=0.05 Breed ut size intertion P=0.06 Figure 4. Pek fore y reed nd ut size in Deep petorl musles. Bos turus Pek sher fore, l d Stek P=0.005 Rost P=0.002 Breed ut size intertion P=0.012 Figure 5. Pek fore y reed nd ut size in Longissimus lumorum musles. 78
Bos turus Pek sher fore, l Stek P 0.001 Rost P 0.001 Breed ut size intertion P=0.38 Figure 6. Pek fore y reed nd ut size in Gluteus medius musles. Bos turus Pek sher fore, l Stek Rost Breed min effet P=0.38 Figure 7. Pek fore y reed nd ut size in Psos mjor musles. 79
Bos turus Pek sher fore, l Stek P=0.074 Rost P=0.918 Breed ut size intertion P=0.38 Figure 8. Pek fore y reed nd ut size in Bieps femoris musles. 80
Bos turus Pek sher fore, l Stek P=0.416 Rost P=0.003 Breed ut size intertion P=0.033 Figure 9. Pek fore y reed nd ut size in Semitendinosus musles. Bos turus Pek sher fore, l d Stek P 0.001 P=0.001 Rost P 0.001 Figure 10. Pek fore y reed nd ut size in Semimemrnosus musles. 81