Supplemental vitamin D3 concentration and biological type of beef steers. I. Feedlot performance and carcass traits

Because of the Ca dependency of the calpains, oral supplementation of vitamin D3 (VITD) can increase the Ca content of muscle to activate the calpains and improve tenderness. Feedlot steers (n = 142) were arranged in a 4 x 3 factorial arrangement consisting of four levels of VITD (0, 0.5, 1, and 5 million IU/[steer x d]) for eight consecutive days antemortem using three biological types (Bos indicus, Bos taurus-Continental, and Bos taurus-English). Feedlot performance factors of ADG, DMI, and G:F were measured, and carcass quality, yield, and color data were collected. Plasma Ca and P concentrations were measured during d 4 to 6 of supplementation and at exsanguination, and carcass pH and temperature were measured in the LM at 3 and 24 h postmortem. Vitamin D3 treatment at 5 million IU/(steer x d) decreased ADG (P < 0.05) over the supplementation and feed intake for the last 2 d of feeding compared with untreated control steers. Likewise, G:F was decreased (P = 0.03) in steers supplemented with 5 million IU/d compared with controls. Overall, there was a linear decrease (P < 0.01) in ADG and G:F as a result of VITD supplementation. Plasma concentrations of Ca and P were increased (P < 0.05) by VITD concentrations of 1 and 5 million IU/(steer x d). All VITD treatments increased (P < 0.05) LM temperature at 3 h postmortem and pH at 24 h postmortem. Vitamin D3 treatments did not affect (P = 0.07) any other carcass measurements, including USDA yield and quality grade; thus, any improvements in meat tenderness as a result of VITD supplementation can be made without adversely affecting economically important carcass factors. Biological type of cattle did not interact with VITD treatment for any carcass or feedlot performance trait. Although feeding 5 million IU/(steer x d) of VITD for eight consecutive days had negative effects on performance, supplementing VITD at 0.5 million IU/ (steer x d) did not significantly alter feedlot performance.     

Vitamin D3 supplementation of cull cows: effects on longissimus and semitendinosus muscle tenderness

Previous studies have shown that supplementation of vitamin D3 to cow diets for 4 to 10 d before slaughter lowers Warner-Bratzler shear force (WBSF) values and increases sensory tenderness scores in beef cuts. The present study was conducted to evaluate the effects of vitamin D3 supplementation on muscle calcium concentration, WBSF values, and sensory tenderness ratings of LM and semitendinosus (ST) muscles from cull, predominately Angus, cows (eight cows per treatment). Treatments included 0 (control), 5 million IU, or 7.5 million IU of vitamin D3 supplemented daily for 7 d preslaughter. Twenty-four hours after slaughter, 2.54-cm-thick LM and ST muscle steaks were cut; aged for either 0, 7, 14, or 21 d (ST steaks aged for 7 d only); and frozen at -20 degrees C for WBFS and sensory analysis. Mean values for LM calcium concentration tended to increase (P = 0.14) with vitamin D3 supplementation (154, 176, and 183 microig/g, fresh basis, for 0, 5, and 7.5 million IU/d, respectively). After 7 d of aging, LM steaks from cows fed 7.5 million IU had lower (P < 0.05) WBSF values than 7-d steaks from controls and cows fed 5.0 million IU/d aged 7 d; however, vitamin D3 supplementation had no (P > 0.05) effect on WBSF values of ST steaks aged 7 d. Vitamin D3 supplementation did not (P > 0.05) affect sensory tenderness ratings for either LM or ST steaks at any aging period. Aging, however, had a linear (P < 0.001) effect on tenderness, with an increase in tenderness as aging time increased from 0 to 21 d. Thus, results from the present study indicate that vitamin D3 supplementation, at these levels and duration before slaughter, provided little benefit to muscle tenderness of beef from cull cows.     

Effects of ractopamine supplementation and postmortem aging on longissimus muscle palatability of beef steers differing in biological type

Effects of ractopamine hydrochloride (RAC) supplementation and postmortem aging on palatability of beef from steers differing in biological type were evaluated using LM samples from British, Continental crossbred, and Brahman crossbred calf-fed steers (n = 98/type). Equal numbers of steers within each type were assigned to treatments of 0 or 200 mg.steer(-1).d(-1) of RAC fed during the final 28 d of the finishing period. Warner-Bratzler shear force (WBSF) was measured at 3, 7, 14, and 21 d postmortem, and trained sensory panel (TP) evaluation was conducted using LM samples aged for 14 d postmortem. A RAC x type interaction (P = 0.006) was detected for WBSF. Within each type, steers fed RAC produced steaks with greater (P < 0.05) WBSF values than steaks from control steers; however, the magnitude of the effect of RAC on WBSF was more pronounced among Brahman cross-breds (5.53 vs. 4.96 +/- 0.10 kg) than among Continental crossbred (4.16 vs. 3.96 +/- 0.10 kg) and British steers (4.10 vs. 3.75 +/- 0.10 kg). The effect of RAC on WBSF, though diminished slightly by aging (mean WBSF difference: 3 d = 0.49 kg; 21 d = 0.24 kg), was not completely mitigated by 21 d of postmortem storage (P(RAC x AGE) = 0.16). Steers fed RAC produced steaks that received lower (P < 0.05) TP ratings for tenderness (8.09 vs. 8.95 +/- 0.18) and juiciness (7.41 vs. 8.07 +/- 0.16 kg), along with slightly lower (P = 0.06) ratings for beef flavor (6.67 vs. 6.93 +/- 0.10 kg), compared with steaks from unsupplemented steers, regardless of biological type. Among the 3 biological types, Brahman crossbred cattle produced steaks with the greatest (P < 0.05) WBSF values at each aging period; WBSF values for steaks from British and Continental type steers did not differ (P > 0.05) at any aging time. Sensory panel ratings of tenderness, juiciness, and beef flavor were greatest (P < 0.05) for steaks from British steers, and least (P < 0.05) for steaks produced by Brahman-type steers. Results from this study suggest that RAC supplementation slightly decreases LM tenderness (WBSF and TP) of British, Continental crossbred, and Brahman cross-bred steers, and that the effect of RAC on WBSF may be more pronounced in steaks from Brahman crossbred cattle than among stenks from Continental type or British steers.     

Effect of vitamin D3 supplementation level on the postmortem tenderization of beef from steers

The objective of this experiment was to determine the effect of different doses of vitamin D3 (VITD) on beef feedlot performance, plasma and muscle Ca2+, tissue residues, and improvement of Warner-Bratzler shear force (WBS) and panel tenderness. A total of 167 steers were fed one of six levels of VITD. The VITD treatments (28 steers/treatment) were 0, 0.5 x 10(6), 1 x 10(6), 2.5 x 10(6), 5 x 10(6), and 7.5 x 10(6) IU/steer daily of VITD fed nine consecutive days before slaughter. Feedlot performance and plasma Ca2+ were measured during the last 21 days on feed. Warner-Bratzler shear force was measured on strip loin and top round steaks at 7, 10, 14, and 21 d postmortem. The VITD treatments of 5 and 7.5 x 10(6) IU/steer daily decreased (P < 0.05) ADG, and VITD supplementation of 2.5, 5, and 7.5 x 10(6) IU/steer daily decreased average dry matter feed intake (P < 0.05) at the end of the feeding trial. Plasma Ca2+ increased linearly with VITD treatment (P < 0.01). Calpastatin and calpain activity were not influenced by treatment (P > 0.05), but muscle Ca2+ was increased (P < 0.05) by VITD treatments of 1, 2.5, 5, and 7.5 10(6) IU/steer daily. Feeding VITD did not influence (P > 0.05) carcass quality or yield traits. Supplementing VITD at levels of 1, 2.5, 5, and 7.5 10(6) IU/steer daily increased (P < 0.05) VITD concentrations in strip loin and liver samples. Cooking liver decreased VITD concentrations 10 to 28%. Vitamin D3 treatments of 0.5 and 7.5 x 10(6) IU/d reduced strip loin steak WBS at d 7 (P < 0.05), but VITD treatments did not decrease strip loin steak WBS at any other time postmortem. The VITD treatments of 0.5, 1, and 5 x 10(6) IU/steer daily decreased top round steak WBS at 7 d, and all VITD treatments decreased 10-d top round steak WBS (P < 0.05). Supplementing steers with 0.5 x 10(6) IU/steer daily of VITD also decreased (P < 0.05) top round steak WBS at 21 d postmortem compared with controls. Sensory tenderness at 7 d postmortem was increased (P < 0.05) by all VITD treatments in top round steaks, yet strip loin tenderness scores were not affected (P > 0.05) by VITD treatment. Treatment with VITD quadratically decreased (P < 0.05) round WBS. Thus, VITD treatment will effectively improve tenderness when cattle tend to be tough and have no impact on cattle that produce tender beef. Feeding steers 0.5 x 10(6) IU of VITD daily for 9 d improved tenderness in two muscles without negatively affecting feedlot performance or tissue residues.     

Effect of supplemental vitamin D3 concentration on concentrations of calcium, phosphorus, and magnesium relative to protein in subcellular components of the longissimus and the distribution of calcium within longissimus muscle of beef steers

The effect of supplementing diets with various levels of vitamin D3 to provide 0, 0.5, 1, and 5 million IU/(steer x d) for 8 d before slaughter on the mineral content and localization of Ca in LM and muscle fragments was studied during the postmortem aging process. Twelve feedlot steers of three biological types were given access to the four levels of vitamin D for 8 d before slaughter. Differential centrifugation techniques were used to determine the concentrations of minerals relative to protein in different muscle fragments on d 3 and 21 postmortem. Electron microscopy visualization of bound Ca indicated that vitamin D3 mobilized Ca from the sarcoplasmic reticulum and transverse tubule system into the myofibrils. Bound Ca was concentrated near the Z-line at the A-band/I-band juncture within the sarcomere. Supplementing steers with 1 and 5 million IU/(steer x d) of vitamin D3 increased (P < 0.05) Ca, P, and Mg concentrations per unit of protein in the cytosol. Soluble cytosolic Ca concentrations were greater (P < 0.05) on d 21 than on d 3 postmortem only when steers were supplemented with 5 million IU/d. Concentrations of Ca, P, and Mg in isolated tissues were increased (P < 0.05) in nuclei and myofibrilar proteins by supplementing steers with 1 and 5 million IU/ (steer x d) of vitamin D3. All supplemental vitamin D3 treatments also increased (P < 0.001) Mg concentrations in the cytosol, regardless of aging treatment, and increased Mg concentrations (P < 0.04) within the mitochondria at d 3 postmortem. Thus, supplementation of feedlot steers with vitamin D3 at levels of 0.5 to 5 million IU/(steer x d) increased Ca concentrations within respiring muscle, resulting in increased bound tissue Ca concentrations. When the respiring muscle was converted to meat, the increased bound tissue Ca resulting from vitamin D3 treatment released Ca concentrations into the cytosol during aging (P < 0.05). Results of this study indicate that vitamin D3 supplementation increased total cytosolic Ca, P, and Mg concentrations in meat.     

Effects of genetic markers and implant strategy on longissimus and gluteus muscle tenderness of calf-fed steers and heifers

Effects of genotype (GEN) and implant program (IMP) on LM and gluteus muscle (GM) tenderization were investigated using crossbred steer (n = 185) and heifer (n = 158) calves. The 3-marker GeneSTAR Tenderness panel [CAST (calpastatin), CAPN1 316 (μ-calpain), and CAPN1 4751 (μ-calpain)] was used to determine the GEN of each animal (reported as total number of favorable alleles, 0 through 6). Calves were randomly assigned to 1 of 2 IMP, conventional (CNV) or delayed. Cattle in the CNV group were implanted at the beginning of the finishing period with Revalor-IS or Revalor-IH (Intervet Inc., Millsboro, DE), and then reimplanted 59 d later with Revalor-S or Revalor-H (Intervet Inc.). Calves in the delayed group received a single terminal implant (Revalor-S or Revalor-H) administered 45 d after initiation of the finishing period. Warner-Bratzler shear force (WBSF) was measured on LM and GM steaks at 3, 7, 14, 21, and 28 d postmortem. No interactions between the main effects of sex, IMP, or GEN were detected (P > 0.05) for WBSF. An IMP × postmortem aging (age) interaction was detected (P < 0.05) for LM and GM WBSF. For both muscles, steaks from CNV cattle had WBSF values that were approximately 0.2 kg greater (P < 0.05) than the values for steaks from delayed animals, but only during the early postmortem period (3 to 7 d). A linear effect of GEN on WBSF was detected (P < 0.05) for LM and GM steaks. Within each muscle, steaks from cattle with 6 favorable alleles had WBSF values 0.33 kg less than the values for steaks from cattle with 1 favorable allele. The GEN × age interaction was not significant for LM (P = 0.14) or GM (P = 0.20), but a numerical trend was observed for the effect of GEN on WBSF to diminish as age increased. To investigate how genetic markers could be interfaced with current beef carcass quality grading, cattle were sorted into 2 gene marker groups (GMG), ≤3 vs. ≥4 favorable alleles. For both muscles, GMG was effective only at identifying tenderness differences within the Select grade. When aged ≤14 d, Select LM steaks from cattle with ≥4 alleles had smaller (P < 0.05) WBSF values than did LM steaks from animals with ≤3 alleles. Preslaughter factors (sex, IMP, and GMG) controlled in the present study each accounted for less than 7% of the explained variation in tenderness of the test population. Results from this study suggest that the 3 GeneSTAR Tenderness markers were associated with small differences (0.33 kg) in WBSF and may be useful for increasing the consistency of Select beef, but these specific markers accounted for only a minor amount of variation in beef tenderness.     

The use of vitamin D3 to improve beef tenderness

An experiment was designed to test the hypothesis that short-term oral administration of dietary vitamin D3 to beef cattle before slaughter would increase beef tenderness through greater calcium-activated calpain activity in postmortem aged skeletal muscle. Thirty continental crossbred steers were allotted randomly to three treatment groups housed in one pen. One group served as a control; two other groups were administered boluses with either 5 x 10(6) or 7.5 x 10(6) IU of vitamin D3 daily for 9 d. Cattle were slaughtered 1 d later. The longissimus lumborum was excised from each carcass 72 h postmortem and steaks removed at 3, 7, 14, and 21 d postmortem. The semimembranosus muscle (top round) was excised from each carcass 72 h postmortem and steaks removed at 7, 14, and 21 d postmortem. Blood plasma calcium concentration of cattle treated with 5 or 7.5 x 10(6) IU of vitamin D3 was higher (P < .05) than that of controls. Strip loin and top loin steaks from cattle fed supplemental doses of vitamin D3 had lower (P < .05) Warner-Bratzler (W-B) shear values at 14 d postmortem but were not significantly different from controls at 3, 7, or 21 d (strip loins) or 7 or 21 d (top rounds). No significant difference in strip loin steak tenderness was observed by sensory panel at 14 d postmortem (P < .17) between steaks from control and vitamin D3-treated steers. At 14 d postmortem, strip loin and top round steaks from cattle fed 5 x 10(6) IU of vitamin D3, but not from those given 7.5 x 10(6) IU, showed more proteolysis (P < .05) than did steaks from control cattle, based on Western blotting analysis. Therefore, the use of supplemental dietary vitamin D3 given daily for 9 d before slaughter did improve tenderness (lower W-B shear values) of 14-d postmortem aged beef. Increased proteolysis seems to be the mechanism of tenderization.     

Effects of postmortem calcium chloride injection on meat palatability traits of strip loin steaks from cattle supplemented with or without zilpaterol hydrochloride

An experiment was conducted to determine the effects of zilpaterol hydrochloride mM supplementation (ZH; 8.3 mg/kg on a DM basis for 20 d) and calcium chloride injection [CaCl(2), 200 at 5% (wt/wt) at 72 h postmortem] on palatability traits of beef (Bos taurus) strip loin steaks. Select (USDA) strip loins were obtained from control (no ZH = 19) and ZH-supplemented carcasses (n = 20). Right and left sides were selected alternatively to serve as a control (no INJ) or CaCl(2)-injected (INJ) and stored at 4°C. Before injecting the subprimals (72 h postmortem), 2 steaks were cut for proximate, sarcomere length, and myofibrillar fragmentation index (MFI) analyses. At 7 d postmortem each strip loin was portioned into steaks, vacuum packaged, and aged for the appropriate period for Warner-Bratzler shear force (WBSF; 7, 14, 21, and 28 d postmortem), trained sensory analysis (14 and 21 d postmortem), purge loss (7 d), and MFI (3, 7, 14, 21, and 28 d postmortem). Results indicated steaks from both ZH supplementation and INJ had reduced WBSF values as days of postmortem aging increased. The WBSF values of ZH steaks were greater (P < 0.05) than no ZH steaks at each postmortem aging period. The INJ steaks had lower WBSF values (P < 0.05) than non-injected steaks. A greater percentage (91 vs. 71%) of steaks had WBSF values < 4.6 kg from steers with no ZH supplementation at 7 d postmortem, but the percentage did not differ (P > 0.05) due to ZH at 14, 21, or 28 d or due to INJ at any aging period. Trained panelists rated tenderness less in ZH steaks than steaks with no ZH at 14 d and 21 d. However, INJ improved (P < 0.05) the tenderness ratings and flavor intensity of the trained panelists, compared with their non-injected cohorts at 21 d. Zilpaterol hydrochloride supplementation reduced (P < 0.05) MFI values, but INJ resulted in greater (P < 0.05) MFI values compared with no INJ. Subprimals from ZH and INJ showed greater purge loss (P < 0.05). Although no interactions were found with ZH and CaCl(2), injecting USDA Select strip loins from ZH-fed cattle can help reduce the normal WBSF variation as it does in steaks from non-ZH-fed cattle.     

Influence of early postmortem protein oxidation on beef quality

The objective of this study was to examine the effect of early postmortem protein oxidation on the color and tenderness of beef steaks. To obtain a range of oxidation levels, the longissimus lumborum muscles (LM) from both strip loins of 20 steers fed either a finishing diet with vitamin E (1,000 IU per steer daily, minimum of 126 d [VITE]; n = 10 steers) or fed the same finishing diet without vitamin E (CON; n = 10 steers) were used. Within 24 h after slaughter, the LM muscle from each carcass was cut into 2.54-cm-thick steaks and individually vacuum packaged. Steaks from each steer were assigned to a nonirradiated group or an irradiated group. Steaks were irradiated within 26 h postmortem, and were aged at 4 degrees C for 0, 1, 3, 7, and 14 d after irradiation. Steaks from each diet/irradiation/aging time treatment were used to determine color, shear force, and degree of protein oxidation (carbonyl content). Steaks from steers fed the VITE diet had higher (P < 0.01) alpha-tocopherol contents than steaks from steers fed the CON diet. Immediately following irradiation, steaks that had been irradiated had lower (P < 0.05) L* values regardless of diet. Irradiated steaks, regardless of diet, had lower a* (P < 0.05) and b* (P < 0.01) values than nonirradiated steaks at all aging times. Carbonyl concentration was higher (P < 0.05) in proteins from irradiated steaks compared to nonirradiated steaks at 0, 1, 3, and 7 d postirradiation. Immunoblot analysis showed that vitamin E supplementation decreased the number and extent of oxidized sarcoplasmic proteins. Protein carbonyl content was positively correlated with Warner-Bratzler shear force values. These results indicate that increased oxidation of muscle proteins early postmortem could have negative effects on fresh meat color and tenderness.     

Effects of supplemental vitamin D3 on feed intake, carcass characteristics, tenderness, and muscle properties of beef steers.

Research was conducted to determine the effects of supplemental dietary vitamin D3 on DMI, carcass traits, Warner Bratzler shear (WBS) force, calpastatin activity, plasma minerals, pH (0, 3, 12, and 24 h after slaughter), water-holding capacity (WHC), and sensory characteristics of three muscles. Pre-slaughter vitamin D3 treatments included no supplemental vitamin D3, 6 x 106 IU (MIU) of vitamin D3 for 4 d, or 6 MIU of vitamin D3 for 6 d. Cattle were slaughtered and carcasses were chilled for 48 h before removal of steaks from the longissimus, gluteus medius, and biceps femoris muscles. Steaks were aged at 2 degrees C for 7, 14, or 21 d before cooking to a final internal temperature of 70 degrees C for WBS and sensory panel analysis. Dry matter intake was lower for steers supplemented with vitamin D3 for 4 or 6 d. Live and carcass weights were lower (P < 0.05) in steers supplemented with vitamin D3. Supplementing 6 MIU/6 d of vitamin D3 decreased (P < 0.05) WBS values of gluteus steaks (pooled over aging times). Longissimus steaks from steers supplemented with vitamin D3 for 6 d had lower (P < 0.05) WBS force values than these steaks from control steers or steers fed vitamin D3 for 4 d at 7 d postmortem. Biceps femoris steaks from steers receiving vitamin D3 for 4 d had higher WBS values than steaks from control steers at 14 and 21 d postmortem. Feeding vitamin D3 at 6 MIU for 6 d decreased (P < 0.05) the percentage of steaks that had WBS values > or = 3.86 kg for all steaks. Feeding vitamin D3 had no effect on palatability traits evaluated by trained panelists. Blood Ca concentrations were greater (P < 0.05) when vitamin D3 was fed and with increased vitamin D3 feeding time. Feeding vitamin D3 for 6 d (vs 4 d) delayed pH decline for all muscle types after 0, 3, and 12 h postmortem. Water-holding capacity was increased (P > 0.02) after 0 h, 24 h, and 21 d postmortem when vitamin D3 was fed and was greater at 0 and 24 h if vitamin D3 was fed for 6 d rather than 4 d. These data suggest that supplementing 6 MIU of vitamin D3 will decrease DMI and improve beef tenderness through increased blood plasma Ca concentrations and WHC.     

Supranutritional oral supplementation with vitamin D3 and calcium and the effects on beef tenderness

Ultimate meat tenderness can be influenced by numerous preslaughter and postmortem management techniques. Increased levels of intracellular Ca2+, through postmortem injection, infusion, or marination, have been shown to improve the tenderness of cooked meat products. Oral supplementation with vitamin D3 effectively increases serum Ca2+ and has been hypothesized to increase muscle Ca2+ content, the activity of muscle proteases, and thus the tenderness of cooked beef. Individual Charolais x Hereford heifers (n = 191) were assigned to an unsupplemented control group or groups that were supplemented via oral bolus (for dose regulation purposes) with one of seven levels of vitamin D3 (1, 2, 3, 4, or 5 x 10(6) IU D3/d, 2 x 10(6) IU DS/d plus 75 g CaCO3 or 4 x 106 IU D3/d plus 75 g CaCO3) for 2, 4, 6, or 8 d antemortem. Individual feedlot performance, serum Ca2+ levels, and carcass data were collected, and eight longissimus steaks/carcass were used to obtain Warner-Bratzler shear force values measured at 2, 7, 14, and 21 d postmortem for longissimus steaks cooked to 70 degrees or 85 degrees C. Cattle supplemented with 4 x 10(6) IU D3/d plus 75 g of CaCO3 had lower daily feed intake (as-fed) and reduced (P < 0.05) average daily gains compared with controls during the 8-d supplementation period. Additionally, supplemented cattle had numerically higher dressing percentages, possibly due to less fill at the time of slaughter, because carcass weights and USDA yield grades did not differ (P > 0.05) across treatment groups. Supplementation with 1, 2, 3, 4, or 5 x 10(6) IU D3/d, for 2 or more days, increased (P < 0.05) serum Ca2+ concentrations compared with controls. Whereas cattle that received additional dietary Ca2+ in the form of CaCO3 had the lowest blood serum Ca2+ concentration. Although blood serum Ca2+ was increased, supplementation with any level of vitamin D3 for any length of time up to 8 d did not improve (P > 0.05) Warner-Bratzler shear force at 2, 7, 14, or 21 d of postmortem aging compared with controls when steaks were cooked to final internal temperatures of either 70 (control means 6.27, 4.91, 4.64, and 3.80 kg, respectively) or 85 degrees C (control means 7.31, 5.32, 4.69, and 4.46 kg, respectively). Results indicated that oral supplementation with vitamin D3 (at high or low doses) for 2 to 8 d before slaughter increased serum Ca2+ concentration but does not improve cooked longissimus tenderness.     

The use of vitamin D3 and its metabolites to improve beef tenderness

Three experiments were conducted to determine whether feeding 25-hydroxyvitamin D3 (25-OH D3) or 1,25-dihydroxyvitamin D3 (1,25-(OH)2 D3) improves the tenderness of longissimus dorsi (LD), semimembranosus (SM), and infraspinatus (IF) muscles similar to supplemental vitamin D3 without leaving residual vitamin D3 and its metabolites in muscle. In the first two experiments, 24 crossbred steers were used to determine the effects of different oral amounts of 1,25-(OH)2 D3 (Exp. 1; n = 12) and 25-OH D3 (Exp. 2; n = 12) on plasma Ca2+ concentrations. In the third experiment, crossbred steers were allotted randomly to one of four treatments: 1) control placebo (n = 7); 2) 5 x 10(6) IU of vitamin D3/d (n = 9) for 9 d and harvested 2 d after last treatment; 3) single, 125-mg dose of 25-OH D3 (n = 8) 4 d before harvest; or 4) single, 500-microg dose of 1,25-(OH)2 D3 (n = 9) 3 d before harvest. The LD and SM steaks from each animal were aged for 8, 14, or 21 d, whereas steaks from the IF were aged for 14 or 21 d. All steaks were analyzed for tenderness by Warner-Bratzler shear force and for troponin-T degradation by Western blot analysis. Supplementing steers with vitamin D3 increased (P < 0.01) the concentration of vitamin D3 and 25-OH D3 in all muscles sampled. Feeding steers 25-OH D3 increased (P < 0.05) the concentration of 25-OH D3 in meat, but to an amount less than half that of cattle treated with vitamin D3. Supplemental 1,25-(OH)2 D3 did not affect (P < 0.10) shear force values; however, there was a trend (P < 0.10) for supplemental vitamin D3 and 25-OH D3 to produce LD steaks with lower shear values after 8 and 14 d of aging, and lower (P < 0.10) shear force values for the SM aged for 21 d. Analysis of Western blots indicated that LD steaks from cattle supplemented with vitamin D3 and 25-OH D3 had greater (P < 0.05) troponin-T degradation. Antemortem supplementation of 25-OH D3 seems to increase postmortem proteolysis and tenderness in the LD and SM without depositing large concentrations of residual vitamin D3 and its metabolite 25-OH D3.     

Use of 25-hydroxyvitamin D3 and vitamin E to improve tenderness of beef from the longissimus dorsi of heifers

The objective of this trial was to determine whether a single bolus of 25-hydroxyvitamin D(3) (25-OH D(3)), vitamin E, or a combination of the 2 would improve the tenderness of steaks from the LM of beef heifers. Forty-eight Angus crossbred heifers were allotted randomly to 8 pens. Six heifers were in each pen, and there were 2 pens per treatment. The 4 treatments included control (no 25-OH D(3) or vitamin E); 25-OH D(3) (500 mg of 25-OH D(3) administered as a one-time oral bolus 7 d before slaughter); vitamin E (1,000 IU of vitamin E administered daily as a top-dress for 104 d before slaughter); or combination (500 mg of 25-OH D(3) administered as a one-time oral bolus 7 d before slaughter and 1,000 IU of vitamin E administered daily as a top-dress for 104 d before slaughter). Blood samples were obtained on the day that heifers were allotted to treatments, on the day 25-OH D(3) was administered, and on the day before slaughter. Plasma calcium concentration was increased when 25-OH D(3) was administered with or without vitamin E (P < 0.007). In LM, calcium concentration tended to increase (P = 0.10) when 25-OH D(3) was administered alone but not when 25-OH D(3) was administered with vitamin E. Concentrations of 25-OH D(3) and 1,25-dihydroxyvitamin D(3) in plasma were increased when 25-OH D(3) was administered with or without vitamin E (P < 0.001). Steaks from heifers treated with 25-OH D(3) or vitamin E, but not both, tended to have lower Warner-Bratzler shear force than steaks in the control group at 14 d postmortem (P = 0.08). Postmortem protein degradation as measured by Western blot of the 30-kDa degradation product of troponin-T was increased with all treatments after 3 d postmortem (P 相似文献   

Effects of biological type and dietary fat treatment on factors associated with tenderness: II. Measurements on beef semitendinosus muscle

The objective of this study was to evaluate attributes in semitendinosus muscle (ST) associated with tenderness in divergent breeds--Wagyu (W; n = 12), Limousin (L; n = 12), and Wagyu x Limousin cross cattle (WxL; n = 12)--fed two dietary treatments (0 or 6% sunflower oil, DM basis). A randomized complete block repeated measures design with a 3 x 2 factorial arrangement of treatments was used to measure effects of breed, diet, block, and associated interactions. Cattle were fed barley-based diets for an average of 259 d. Temperature and pH were measured at 0, 1, 3, 6, 12, and 24 h postmortem (PM). Steaks from the ST were removed 24 h postmortem, vacuum-packaged, aged (1, 3, 7, 14, 28, and 56 d postmortem) at 2 degrees C, and frozen (-40 degrees C) until analyzed. Dietary treatment did not (P > 0.10) affect Warner-Bratzler shear force (WBSF), collagen amount (OH-PRO) or cross-linking (HP), temperature, or pH. Steaks from WxL aged 14 d postmortem had lower (P < 0.05) WBSF values than L (W were intermediate). Cooking time was longer (P < 0.01) in W and WxL than in L; however, breed did not affect (P > 0.10) cooking loss. Cooking time was not influenced by diet, but steaks from cattle fed 6% sunflower oil had lower (P < 0.05) cooking losses. Temperature decreased more (P < 0.05) rapidly, and pH more slowly (P < 0.05), in W and WxL than L in the first 24 h postmortem. Limousin steaks were lighter (higher L*) and more yellow (higher b*) in color than steaks from W and WxL (P < 0.05). The control diet (no oil added) resulted in steaks that were lighter (P < 0.05) than the treatment diet (6% added sunflower oil). Neither breed nor diet affected (P > 0.10) OH-PRO or HP concentration. The results of this study indicate that biological type differences may not be as great in the ST as in longissimus muscle; thus, to increase tenderness in ST, emphasis may need to be placed on processing and cooking techniques rather than genetic selection.     

Characterization of estrogen-trenbolone acetate implants on tenderness and consumer acceptability of beef under the effect of 2 aging times

Anabolic steroid implants are commonly used to increase growth performance and carcass leanness. The objective of this study was to determine the effects of various trenbolone acetate implants on Warner-Bratzler shear force (WBSF), slice shear force, and consumer palatability ratings for USDA Choice and Select beef strip steaks aged for 14 and 21 d from cattle implanted before slaughter. Beef steers (n = 1,740) were subjected to the following treatments: 1) nonimplanted control (CON); 2) Revalor-IS on d 0 and Revalor-S on d 70 (IS/S); or 3) Revalor-XS (RXS) on d 0, and were randomly assigned to pens within blocks. A subsample of USDA Choice (n = 82) and USDA Select (n = 81) carcasses was selected. Strip loins from these carcasses were collected, and steaks measuring 2.54 cm were fabricated and aged for 14 or 21 d postmortem. Select steaks aged 14 d from RXS cattle had decreased (P < 0.05) WBSF values compared with IS/S steaks, but CON steaks did not differ from either implant treatment. Warner-Bratzler shear force did not differ among treatments (P > 0.05) from USDA Choice steaks aged 14 and 21 d or from Select steaks aged 21 d. Consumer scores for flavor and overall liking for USDA Choice 14-d aged RXS steaks were less (P < 0.05) than CON steaks; however, there were no differences between RXS, IS/S, and CON for tenderness or juiciness, or for tenderness and overall acceptability. Select steaks aged 14 d from IS/S cattle had less (P < 0.05) tenderness, tenderness acceptability, overall acceptability, overall liking, juiciness, and flavor scores than RXS and CON steaks; however, consumers also rated RXS steaks less for tenderness, juiciness, and tenderness acceptability when compared with CON steaks. Consumer scores for overall liking, flavor, and tenderness for USDA Choice steaks aged 21 d from RXS, IS/S, and CON did not differ. However, implant affected (P < 0.05) overall liking, flavor, juiciness, and tenderness for USDA Select steaks aged 21 d. Even so, there were no differences between RXS, IS/S, and CON steaks for tenderness or overall acceptability for steaks aged 21 d, regardless of quality grade. Results indicated that tenderness differences exist among implant strategies when strip steaks were aged 14 d; however, tenderness and overall consumer acceptability were only influenced by implant in Select steaks aged 14 d. Furthermore, aging for 21 d can minimize and even eliminate implant differences in WBSF and slice shear force, as well as tenderness and overall consumer acceptability.     

Oxidative environments decrease tenderization of beef steaks through inactivation of mu-calpain

This study was designed to test the hypothesis that oxidative conditions in postmortem (PM) tissue decrease calpain activity and proteolysis, subsequently minimizing the extent of tenderization. To achieve different levels of oxidation, the diets of beef cattle were supplemented with vitamin E for the last 126 d on feed, and beef steaks were irradiated early PM. Ten steers were fed a finishing diet with the inclusion of vitamin E at 1,000 IU per steer daily (VITE). Another 10 beef steers were fed the same finishing diet without added vitamin E (CON). At 22 to 24 h PM, strip loins from each carcass were cut into 2.54-cm-thick steaks and individually vacuum packaged. Within 26 h PM, steaks were irradiated at 0 or 6.4 kGy and then aged at 4 degrees C for 0, 1, 3, 7, and 14 d postirradiation. Steaks from each time point were used to determine Warner-Bratzler shear force (WBSF) and calpain activity, and for western blotting of sarcoplasmic proteins and myofibrillar proteins. Calpastatin activity was determined at 0, 3, and 14 d postirradiation. At 1, 3, 7, and 14 d postirradiation, WBSF values of irradiated steaks were higher (P < 0.03) than for nonirradiated steaks. Western blots of troponin-T and desmin showed decreased proteolysis in irradiated samples compared with nonirradiated samples. At 2 d PM, troponin-T degradation products were more evident (P < 0.03) in nonirradiated steaks supplemented with VITE than nonirradiated steaks from the CON diet. Similarly, VITE treatment resulted in steaks with lower (P < 0.05) calpastatin activity at 1 d PM than in steaks from steers fed the CON diet. Irradiation diminished the rate of calpastatin inactivation. Irradiated samples, regardless of diet, had no detectable levels of intact titin or nebulin. Irradiation decreased mu-calpain activity and autolysis, whereas mu-calpain activity was not affected by diet or irradiation. Inactivation of mu-calpain by oxidation during early times PM decreased the amount of myofibrillar proteolysis, thereby decreasing the extent of tenderization of beef steaks.     

Shear gradient in longissimus steaks

Boneless top loin subprimals (n = 320) from Slight and Small marbled carcasses were fabricated into 2.54-cm thick steaks to determine core location effects on tenderness. In Exp. 1, top loins were aged to 7 d before steaks were cut and cooked to an internal temperature of 71 degrees C. After cooking, a maximum of 15 1.27-cm diameter cores were removed and sheared with a Warner-Bratzler shear force (WBSF) device. There was not a marbling score x core location interaction (P = 0.36). However, there was a main effect of core location (P < 0.01). Cores from the medial, middle, and lateral portion of the longissimus muscle (LM) aged for 7 d differed, with less resistance (P < 0.05) in the medial than the lateral end. Also, there was an effect of marbling score on WBSF, with Small-marbled steaks having lower (P < 0.02) WBSF values than Slight-marbled steaks. In a second experiment, steaks were removed from the middle of the top loin subprimals and aged an additional 7 d to produce 14-d aged steaks. Shear values decreased (P < 0.05) from Exp. 1 to 2 for all core locations. Neither the main effect of marbling score nor the core location x marbling score interaction was significant (P > 0.40); however, the same lateral to medial gradient in WBSF values was discovered again in Exp. 2. Both experiments indicated there were regions of WBSF values that differed (P < 0.05) across the cross section of the LM producing a shear-force/tenderness gradient, with the most medial cores having the lowest WBSF values in both experiments independent of marbling score. Regression analyses indicated the middle and center portions of LM steaks tended to have the most predictive capacity of average WBSF. Because of the variability in tenderness caused by location within the LM, care should be exercised when selecting sampling areas for the measurements of tenderness using the WBSF measure.     

Influence of quality classification, aging period, blade tenderization, and endpoint cooking temperature on cooking characteristics and tenderness of beef gluteus medius steaks

Top sirloin butts (n = 162) were used to investigate the influence of quality classification, aging period, blade tenderization passes, and endpoint cooking temperature on the tenderness of gluteus medius steaks. Top sirloin butts (gluteus medius) from Select (SEL), Choice (CHO), and Certified Angus Beef (CAB) carcasses were obtained, aged for 7, 14, or 21 d, and either not tenderized or blade tenderized one or two times. Three steaks from each top sirloin butt were randomly selected and assigned to a final endpoint cooking temperature of 65.5, 71.0, or 76.6 degrees C. Cooking characteristics and Warner-Bratzler shear force (WBSF) were analyzed as a split-plot with a 3 x 3 x 3 factorial treatment structure of quality classification, aging period, and tenderization passes in the whole plot and endpoint cooking temperature in the subplot. Sensory panel data for CHO steaks cooked to 70 degrees C were analyzed with a 3 x 3 factorial treatment structure of aging period and tenderization passes. Thawing loss was greater (P < 0.05) for steaks aged 7 d than those aged 21 d. Cooking loss was greater (P < 0.05) for steaks aged for 14 and 21 d than those aged 7 d, and increased (P < 0.05) with each increasing endpoint temperature. Each increase in aging period resulted in lower (P < 0.05) WBSF values. In addition, steaks blade tenderized two times had lower (P < 0.05) WBSF values than steaks blade tenderized once or not at all. Within each quality classification, WBSF values increased (P < 0.05) as endpoint cooking temperature increased. When cooked to 71 or 76.6 degrees C, CHO and CAB steaks had lower (P < 0.05) WBSF than SEL steaks. Steaks blade tenderized one or two times received higher (P < 0.05) sensory panel ratings for myofibrillar and overall tenderness than steaks not blade tenderized. Connective tissue amount and overall tenderness ratings were higher (P < 0.05) for steaks aged 21 vs. 7 d. Postmortem aging and blade tenderization of gluteus medius steaks can improve tenderness, as measured by WBSF and sensory panel, without decreasing flavor or juiciness. When cooking to higher endpoint temperatures, higher quality classifications should be selected to minimize toughness due to cooking.     

Tasco supplementation: effects on carcass characteristics, sensory attributes, and retail display shelf-life

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.     

Effects of biological type and dietary fat treatment on factors associated with tenderness: I. Measurements on beef longissimus muscle

The objective was to evaluate chemical, mechanical, and sensory attributes associated with tenderness in divergent cattle breeds--Wagyu (W; n = 12), Limousin (L; n = 12) and F1-cross (WxL; n = 12)--fed two dietary treatments (0 or 6% sunflower oil (DM basis)). A randomized complete block repeated measures design in a 3 x 2 factorial arrangement of treatments was used, and effects of breed, diet, block, and associated interactions were tested. Cattle were fed barley-based diets for an average of 259 d. Twenty-four hours postmortem (PM), steaks from the longissimus muscle (LM) were sliced, vacuum-packaged, aged (1, 3, 7, 14, 28, and 56 d PM) at 2 degrees C, and frozen (-40 degrees C) until analyzed. Wagyu steaks had lower (P < 0.05) Warner-Bratzler shear force (WBSF) values than L steaks across all aging times. At 1 d PM, W steaks required slightly more (P > 0.05) force to shear than WxL or L (0.30 and 0.11 kg, respectively); however, by d 14 PM, W steaks required 0.77 kg less (P < 0.05) force to shear than L. Wagyu steaks received higher (P < 0.05) sensory panel sustained tenderness scores at d 14 PM than L. The pH decline was slower (P < 0.05), and temperature decline more (P < 0.05) rapid, in W carcasses than L or WxL carcasses. Breed and diet did not affect (P > 0.10) free calcium levels (FCL) over time (0, 1, 3, 7, and 14 d PM), 0-h calpastatin activity (CA), d-1 percent collagen (OH-PRO), or d-1 collagen cross-linking (HP). Western blot analysis for the presence of the troponin-T (TNT) 30-kDa fragment, conducted only on samples from steers fed the 0% sunflower oil diet, demonstrated more proteolysis by d 3 PM in L than W or WxL. Overall, breed differences in mechanical and sensory measures of tenderness were not explained by FCL, CA, OH-Pro, and HP. Even though the initial appearance of the TNT 30-kDa fragment was greater in L, linear slopes for appearance of TNT degradation product across aging time were greater for W and WxL (P < 0.01 and P = 0.056, respectively) than for L, suggesting that tenderness differences due to breed may have been facilitated by more-rapid proteolytic degradation over time.