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.

Beef customer satisfaction: USDA quality grade and marination effects on consumer evaluations of top round steaks1

An in-home beef study evaluated consumer ratings of top round steaks (semimembranosus) as influenced by USDA quality grade (top Choice or high Select), city (Chicago or Philadelphia), consumer segment (beef loyalists = heavy consumers of beef; budget rotators = cost-driven and split meat consumption between beef and chicken; and variety rotators = higher incomes and education and split meat consumption among beef, poultry, and other foods), degree of doneness, cooking method, and marination. Consumers evaluated each steak for overall like, tenderness, juiciness, flavor like, and flavor amount using 10-point scales (1 = dislike extremely, not at all tender, not at all juicy, dislike extremely, and none at all to 10 = like extremely, extremely tender, extremely juicy, like extremely, and an extreme amount of flavor, respectively). Quality grade affected several consumer sensory traits, with top Choice receiving higher (P < or = 0.004) tenderness, juiciness, and flavor like scores than high Select. Consumers in Chicago rated steaks cooked "medium and less" higher for overall like, tenderness, juiciness, flavor like, and flavor amount than those in Philadelphia (city x degree of doneness; P < or = 0.020). Steaks braised by customers in Philadelphia received among the highest scores for overall like, tenderness, juiciness, flavor like, and flavor amount compared with any cooking method used by customers in Chicago (cooking method x city; P < or = 0.026). Overall like and flavor amount ratings were least (P < 0.05) for steaks that were marinated and cooked to "medium and less" degree of doneness (marination x degree of doneness; P < or = 0.014). Braised steaks received among the highest values for overall like, tenderness, juiciness, flavor like, and flavor amount when cooked to "medium and less" or "medium well and more" (cooking method x degree of doneness; P < or = 0.008). Correlation and stepwise regression analysis indicated that flavor like was pivotal in customers' satisfaction with top round steaks, and was the sensory trait most highly correlated to overall like, followed by tenderness, flavor amount, and juiciness. Preparation of top round steaks was crucial in consumers' likes and dislikes, and by improving flavor, higher consumer satisfaction may be achieved.

Timing of magnesium supplementation administered through drinking water to improve fresh and stored pork quality

Thirty-two pigs were used to determine the timing effect of magnesium (Mg) supplementation given through drinking water on pork quality. Pigs (16 barrows and 16 gilts) were individually penned, provided 2.7 kg of feed (0.12% Mg) daily (as-fed basis), and allowed free access to water via a nipple waterer for the duration of the study. After 5 d of adjustment, pigs (120 +/- 0.8 kg BW) were allotted randomly by weight and sex to 900 mg/L of supplemental Mg from magnesium sulfate heptahydrate in drinking water for -6, -4, -2, or 0 d relative to slaughter. The LM and semimembranosus (SM) muscles were removed 24 h postmortem. Retail display storage was simulated for 8 d, and the LM was vacuum-packaged for 25 or 50 d at 4 degrees C. Magnesium did not affect the pH of the LM at either 45 min (P = 0.15) or 24 h postmortem (P = 0.23). However, the pH of the SM at 24 h postmortem tended to be greater (P = 0.08) for pigs consuming Mg for 2 d than for those not supplemented. Fluid loss after 8 d of storage was less (P < 0.05) in the LM of pigs supplemented with Mg for 6 d than in those without supplementation. Furthermore, fluid loss from the SM of pigs provided supplemental Mg for 2 d, but not for 4 or 6 d, was lower (P < 0.05) on each day of retail display than the SM of unsupplemented pigs. Minolta L*, a*, and b* color measurements of the LM during display storage were not (P > 0.10) affected by Mg supplementation. However, Mg supplementation for 2 or 4 d decreased paleness (lower L* value) after 25 d (P < 0.05), but not 50 d (P > 0.10) of vacuum-packaged storage. Magnesium addition for 2 d decreased the extent of oxidation (thiobarbituric acid-reactive substances) of the LM after 4 d of display storage compared with 0 d of Mg (P < 0.05). Oxidation of the SM during 8 d of display storage increased linearly (P < 0.05) as duration of supplementation increased from 2 to 6 d but did not differ (P = 0.22) from 0 d of Mg supplementation. Although the response to Mg supplementation was variable, supplementation for 2 d before slaughter was considered most efficacious because of the following: decreased fluid loss from the SM, and lower lipid oxidation formation in the LM during retail storage; a darker, more desirable LM color after 25 d of vacuum-packaged storage; and cost reductions compared with longer durations.

Characterization of certified Angus beef steaks from the round, loin, and chuck

Beef carcasses (n = 150) of A-maturity were selected randomly to determine baseline shear force and sensory panel ratings, assess variation in tenderness, and evaluate mean value differences between Certified Angus Beef (CAB), commodity Choice, and Select steaks. Three steaks were removed from the triceps brachii (TB), longissimus lumborum (LL), gluteus medius (GM), semimembranosus (SM), biceps femoris (BF), and quadriceps femoris complex (QF), and assigned to Warner-Bratzler shear (WBSF) and sensory panel analyses. As anticipated, marbling score and measured percentage of i.m. fat were greatest (P < 0.05) for CAB, intermediate (P < 0.05) for Choice, and least (P < 0.05) for Select carcasses. A muscle x quality level interaction (P < 0.05) was observed for WBSF values and sensory panel tenderness ratings. The TB, LL, GM, and BF steaks from CAB carcasses had lower (P < 0.05) WBSF than Select steaks from the same muscles. Even though WBSF values did not differ (P > 0.05) between CAB and Choice QF and TB steaks, the LL and GM steaks from CAB carcasses were more tender (P < 0.05) than Choice-grade LL and GM steaks. The TB from Select carcasses had higher (P < 0.05) WBSF values than TB steaks from CAB or Choice carcasses, but sensory panel ratings indicated that quality level showed little consistency among the GM, SM, BF, and QF. Trained sensory panelists rated CAB LL steaks more tender (P < 0.05) than LL steaks from Choice and Select carcasses, and Choice LL steaks were evaluated as more (P < 0.05) tender than those from Select carcasses. These results demonstrate that the influence of marbling on tenderness was more evident in muscles of middle meats than in end cuts, particularly in muscles of the round.

The relationships among body weight, body composition, and intramuscular fat content in steers

Angus steers of known age (265 +/- 17 d) and parentage were used in a 2-yr study (yr 1, n = 40; yr 2, n = 45) to evaluate the relationship between percentage of i.m. fat content of the longissimus dorsi at the 12th rib and carcass characteristics during growth of nonimplanted steers. Steers were sorted by age and EPD of paternal grandsire for marbling into high- and low-marbling groups so that steers with varying degrees of genetic potential for marbling were evenly distributed across slaughter groups. All steers were fed a 90% concentrate corn-based diet. Steers were allotted to five slaughter groups targeted to achieve hot carcass weights (HCW) of 204, 250, 295, 340, and 386 kg over the course of the feeding period. Data were analyzed as a completely random design with a factorial arrangement of treatments (year, marbling group, and slaughter group). Marbling group did not affect backfat, LM area, yield grade (YG), or marbling score. Regression equations were developed to quantify the change in carcass characteristics and composition over slaughter groups. Hot carcass weight increased in a linear fashion and differed (P < 0.01) among the slaughter groups as anticipated by design. Yield grade followed a quadratic upward pattern (P < 0.01) as HCW increased. Slaughter group affected the degree of marbling linearly (P < 0.01). There were no slaughter group x marbling group interactions, indicating that no differences occurred in the pattern of marbling attributable to paternal grandsire EPD. Carcasses expressed small degrees of marbling at 266 kg of HCW and obtained a YG of 3.0 at 291 kg of HCW. Fractional growth rates decelerated with increasing HCW. Greater advances in marbling relative to total carcass fatness occurred at HCW less than 300 kg. Management practices early in growth may influence final quality grade if compensatory i.m. fat content development does not occur.

Characterization of biological types of cattle (Cycle VI): carcass, yield, and longissimus palatability traits

Carcass (n = 568) and longissimus thoracis palatability (n = 460) traits from F1 steers obtained from mating Hereford (H), Angus (A), and U.S. Meat Animal Research Center (MARC) III cows to H, A, Norwegian Red (NR), Swedish Red and White (RW), Friesian (F), or Wagyu (W) sires were compared. Data were adjusted to constant age (471 d), carcass weight (356 kg), fat thickness (1.0 cm), percentage of fat trim (24%), and marbling (Small35) end points. For Warner-Bratzler shear force and trained sensory panel traits, data were obtained on longissimus thoracis steaks stored at 2 degrees C for 14 d postmortem. The following comparisons were from the age-constant end point. Carcasses from H- and A-sired steers (377 and 374 kg, respectively) were the heaviest (P < 0.05) and carcasses from W-sired steers (334 kg) were the lightest (P < 0.05). A greater (P < 0.05) percentage of carcasses from A- and W-sired steers graded USDA Choice (88 and 85%, respectively) than carcasses from other sire breeds (52 to 71%). Adjusted fat thickness for carcasses from A-sired steers (1.3 cm) was highest (P < 0.05), followed by H-sired steers (1.1 cm) and W- and F-sired steers (0.9 cm); NR- and RW-sired steers (0.8 cm) had the lowest (P < 0.05) adjusted fat thickness. Longissimus thoracis area was not different (P > 0.05) among sire breeds (mean = 80.6 cm2). Carcass yield of boneless, totally trimmed retail product was least (P < 0.05) for A-sired steers (60.1%), intermediate for H-sired steers (61.5%), and similar (P > 0.05) for all other sire breeds (62.5 to 62.8%). Longissimus thoracis steaks from carcasses of A- (3.7 kg) and W-sired (3.7 kg) steers had lower (P < 0.05) shear force values than longissimus thoracis steaks from other sire breeds (4.1 to 4.2 kg). Trained sensory panel tenderness, juiciness, or beef flavor intensity ratings for longissimus thoracis steaks did not differ (P > 0.05) among the sire breeds. Sire breed comparisons were affected by adjusting data to other end points. Heritability estimates for various carcass, yield, and palatability traits ranged from very low (h2 = 0.06 for percentage of kidney, pelvic, and heart fat) to relatively high (h2 = 0.71 for percentage of retail product yield). Relative to the other sire breeds, W-sired steers had the highest percentage of USDA Choice, Yield grade 1 and 2 carcasses, but their carcasses were the lightest.

Integrating linkage and radiation hybrid mapping data for bovine chromosome 15

BACKGROUND

Bovine chromosome (BTA) 15 contains a quantitative trait loci (QTL) for meat tenderness, as well as several breaks in synteny with human chromosome (HSA) 11. Both linkage and radiation hybrid (RH) maps of BTA 15 are available, but the linkage map lacks gene-specific markers needed to identify genes underlying the QTL, and the gene-rich RH map lacks associations with marker genotypes needed to define the QTL. Integrating the maps will provide information to further explore the QTL as well as refine the comparative map between BTA 15 and HSA 11. A recently developed approach to integrating linkage and RH maps uses both linkage and RH data to resolve a consensus marker order, rather than aligning independently constructed maps. Automated map construction procedures employing this maximum-likelihood approach were developed to integrate BTA RH and linkage data, and establish comparative positions of BTA 15 markers with HSA 11 homologs.

RESULTS

The integrated BTA 15 map represents 145 markers; 42 shared by both data sets, 36 unique to the linkage data and 67 unique to RH data. Sequence alignment yielded comparative positions for 77 bovine markers with homologs on HSA 11. The map covers approximately 32% of HSA 11 sequence in five segments of conserved synteny, another 15% of HSA 11 is shared with BTA 29. Bovine and human order are consistent in portions of the syntenic segments, but some rearrangement is apparent. Comparative positions of gene markers near the meat tenderness QTL indicate the region includes separate segments of HSA 11. The two microsatellite markers flanking the QTL peak are between defined syntenic segments.

CONCLUSIONS

Combining data to construct an integrated map not only consolidates information from different sources onto a single map, but information contributed from each data set increases the accuracy of the map. Comparison of bovine maps with well annotated human sequence can provide useful information about genes near mapped bovine markers, but bovine gene order may be different than human. Procedures to connect genetic and physical mapping data, build integrated maps for livestock species, and connect those maps to more fully annotated sequence can be automated, facilitating the maintenance of up-to-date maps, and providing a valuable tool to further explore genetic variation in livestock.

Evaluating consumer acceptability of various muscles from the beef chuck and rib

One hundred thirty-eight consumers evaluated steaks from the complexus (CX), infraspinatus (IF), serratus ventralis (SV), supraspinatus (SS), and triceps brachii (TB) from the wholesale beef chuck; the deep pectoral (DP) from the wholesale brisket; and the longissimus thoracis (LT) from the wholesale rib. The LT was used as a reference for comparison to the other muscles. Ten USDA Choice and ten USDA Select boneless boxed beef subprimals were used for each muscle. Subprimals were aged 14 d from box date, frozen, and cut into 2.5-cm-thick steaks. Consumers rated the IF highest (P < 0.05) for overall like, tenderness, juiciness, and flavor, and assigned it the highest (P < 0.05) price/0.45 kg. The TB also was rated higher (P < 0.05) than the LT for overall like, tenderness, juiciness, flavor, and price/0.45 kg. The SV and CX were rated as being similar (P < 0.05) to the LT for overall like, tenderness, juiciness, flavor, and price/0.45 kg. Consumers rated the SS lower (P < 0.05) than the LT for tenderness, juiciness, flavor, and price. The DP was rated as the toughest, driest, and blandest (P < 0.05), resulting in assignment of the lowest (P < 0.05) price/0.45 kg. Differences in palatability ratings due to quality grade were found for several muscles; USDA Choice SV and SS were rated higher (P < 0.05) for overall like, tenderness, and juiciness than USDA Select SV and SS. For the IF, USDA Choice was rated higher (P < 0.05) for tenderness and juiciness than USDA Select. The USDA Choice TB was rated higher (P < 0.05) for juiciness, and the USDA Choice DP was rated higher (P < 0.05) for overall like, than their USDA Select counterparts. Tenderness, juiciness, and flavor ratings were correlated with overall like ratings (r = 0.84, 0.77, and 0.76, respectively) and with price (r = 0.73, 0.70, and 0.68, respectively). These results indicate the IF, TB, SV, and CX were acceptable, whereas and the SS and DP were unacceptable as steaks.

Different measures of energetic efficiency and their phenotypic relationships with growth, feed intake, and ultrasound and carcass merit in hybrid cattle1

Residual feed intake (RFI) has been proposed as an index for determining beef cattle energetic efficiency. Although the relationship of RFI with feed conversion ratio (FCR) is well established, little is known about how RFI compares to other measures of efficiency. This study examined the phenotypic relationships among different measures of energetic efficiency with growth, feed intake, and ultrasound and carcass merit of hybrid cattle (n = 150). Dry matter intake, ME intake (MEI), ADG, metabolic weight (MWT), and FCR during the test averaged 10.29 kg/d (SD = 1.62), 1,185.45 kJ/(kg0.75 x d) (SD = 114.69), 1.42 kg/d (SD = 0.25), 86.67 kg0.75 (SD = 10.21), and 7.27 kg of DM/kg of gain (SD = 1.00), respectively. Residual feed intake averaged 0.00 kg/d and ranged from -2.25 kg/d (most efficient) to 2.61 kg/d (least efficient). Dry matter intake (r = 0.75), MEI (r = 0.83), and FCR (r = 0.62) were correlated with RFI (P < 0.001) and were higher for animals with high (>0.5 SD) RFI vs. those with medium (+/-0.5 SD) or low (<0.5 SD) RFI (P < 0.001). Partial efficiency of growth (PEG; energetic efficiency for ADG) was correlated with RFI (r = -0.89, P < 0.001) and was lower (P < 0.001) for high- vs. medium- or low-RFI animals. However, RFI was not related to ADG (r = -0.03), MWT (r = -0.02), relative growth rate (RGR; growth relative to instantaneous body size; r = -0.04), or Kleiber ratio (KR; ADG per unit of MWT; r = -0.004). Also, DMI was correlated (P < 0.01) with ADG (r = 0.66), MWT (r = 0.49), FCR (r = 0.49), PEG (r = -0.52), RGR (r = 0.18), and KR (r = 0.36). Additionally, FCR was correlated (P < 0.001) with ADG (r = -0.63), PEG (r = -0.83), RGR (r = -0.75), and KR (r = -0.73), but not with MWT (r = 0.07). Correlations of measures of efficiency with ultrasound or carcass traits generally were not different from zero except for correlations of RFI, FCR, and PEG, respectively, with backfat gain (r = 0.30, 0.20, and -0.30), ultrasound backfat (r = 0.19, 0.21, and -0.25), grade fat (r = 0.25, 0.19, and -0.27), lean meat yield (r = -0.22, -0.18, and 0.24), and yield grade (r = 0.28, 0.24, and -0.25). These phenotypic relationships indicate that, compared with other measures of energetic efficiency, RFI should have a greater potential to improve overall production efficiency and PEG above maintenance, and lead to minimal correlated changes in carcass merit without altering the growth and body size of different animals.

Mechanical probes can predict tenderness of cooked beef longissimus using uncooked measurements1

Two experiments were conducted to determine the effectiveness of using mechanical probes and objective color measurement on beef LM to predict cooked tenderness. In Exp. 1, sharp needle (SN), sharp blade (SB), blunt needle (BN), blunt blade (BB), and plumb bob (PB) probes were used to measure uncooked LM (n = 29) at 2 d postmortem in both a perpendicular and parallel orientation to the long axis of the strip loin. Additionally, instrumental color measurements were measured on uncooked muscle at 2 d postmortem. Steaks for trained sensory panel (TSP) and Warner-Bratzler shear force (WBSF) measurements were aged 14 d postmortem before cooking. Probe measurements taken perpendicular to the long axis of the LM were not correlated (P = 0.22 to 0.82) to TSP tenderness. Probe measurements (BB, BN, SN, SB, and PB) taken parallel to the long axis were correlated to TSP tenderness (r = -0.57, -0.40, -0.77, -0.52, and -0.53, respectively). A regression equation using the SN probe to predict TSP tenderness had a R2 value of 0.74. The SB probe combined with L* accounted for 45% of the variation in TSP tenderness, whereas the PB probe combined with L* accounted for 56% of the variation in TSP tenderness. A second experiment (n = 24) was conducted using the SN, SB, and PB probes on uncooked sections at 2 d and on cooked steaks at 14 d postmortem. Probe measurements on cooked steaks were not correlated to TSP tenderness. New regression equations were calculated using the probe measurements on uncooked steaks from both experiments. Prediction equations formulated with L* values and either SN, SB, or PB probes accounted for 49, 50, and 47% of the variability in TSP tenderness scores, respectively. An equation using WBSF of cooked steaks to predict TSP tenderness had an R2 of 0.58. Of the steaks predicted to be tender (predicted tenderness > 5.0) by the equations using the SN, SB, and PB probes on uncooked steaks and WBSF on cooked steaks, 85, 88, 80, and 84%, respectively, were actually tender (TSP tenderness > 5.0). Mechanical probe measurements of uncooked steaks at 2 d postmortem can potentially classify strip loins into groups based on tenderness, as well as WBSF measurements, which are more costly and time consuming.

Development and validation of equations utilizing lamb vision system output to predict lamb carcass fabrication yields1

This study was performed to validate previous equations and to develop and evaluate new regression equations for predicting lamb carcass fabrication yields using outputs from a lamb vision system-hot carcass component (LVS-HCC) and the lamb vision system-chilled carcass LM imaging component (LVS-CCC). Lamb carcasses (n = 149) were selected after slaughter, imaged hot using the LVS-HCC, and chilled for 24 to 48 h at -3 to 1 degrees C. Chilled carcasses yield grades (YG) were assigned on-line by USDA graders and by expert USDA grading supervisors with unlimited time and access to the carcasses. Before fabrication, carcasses were ribbed between the 12th and 13th ribs and imaged using the LVS-CCC. Carcasses were fabricated into bone-in subprimal/primal cuts. Yields calculated included 1) saleable meat yield (SMY); 2) subprimal yield (SPY); and 3) fat yield (FY). On-line (whole-number) USDA YG accounted for 59, 58, and 64%; expert (whole-number) USDA YG explained 59, 59, and 65%; and expert (nearest-tenth) USDA YG accounted for 60, 60, and 67% of the observed variation in SMY, SPY, and FY, respectively. The best prediction equation developed in this trial using LVS-HCC output and hot carcass weight as independent variables explained 68, 62, and 74% of the variation in SMY, SPY, and FY, respectively. Addition of output from LVS-CCC improved predictive accuracy of the equations; the combined output equations explained 72 and 66% of the variability in SMY and SPY, respectively. Accuracy and repeatability of measurement of LM area made with the LVS-CCC also was assessed, and results suggested that use of LVS-CCC provided reasonably accurate (R2 = 0.59) and highly repeatable (repeatability = 0.98) measurements of LM area. Compared with USDA YG, use of the dual-component lamb vision system to predict cut yields of lamb carcasses improved accuracy and precision, suggesting that this system could have an application as an objective means for pricing carcasses in a value-based marketing system.

Supplemental vitamin D3 concentration and biological type of beef steers. I. Feedlot performance and carcass traits1

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.

Effects of biological type of beef steers on vitamin D, calcium, and phosphorus status1

Feedlot steers (n = 36) from three biological types (Bos indicus, Bos taurus-Continental, and Bos taurus-English) were used to determine the Ca, P, and vitamin D3 status of feedlot cattle. The USDA yield and quality grade traits were measured at slaughter, and the concentrations of vitamin D3 (VITD) and the metabolites 25-hydroxyvitamin D3 (25-OH D) and 1,25-dihydroxyvitamin D3 (1,25-(OH)2 D) were determined in LM, liver, kidney, and plasma. Plasma and muscle Ca and P concentrations also were determined. Biological type of cattle affected a number of carcass traits. Carcasses from Bos taurus-English cattle had more marbling, resulting in higher quality grades (P < 0.05). Carcasses from Bos taurus-Continental cattle had lower calculated yield grades (P < 0.05) than did carcasses from cattle in the other biological types. In general, differences in carcass traits resulting from biological type were consistent with other reports. Plasma and LM Ca and P concentrations were not affected (P = 0.06) by biological type of cattle, indicating that Ca and P homeostasis is a conserved trait across the different types of cattle. Plasma VITD and 25-OH D concentrations were not affected (P = 0.41) by biological type, whereas plasma 1,25-(OH)2 D concentration was lower (P < 0.05) in Bos taurus-English cattle than in Bos taurus-Continental and Bos indicus cattle. Liver VITD and 25-OH D were not affected by biological type (P = 0.76), but liver 1,25-(OH)2 D concentration was greater (P < 0.05) in Bos indicus cattle than in Bos taurus-Continental cattle. Kidney vitamin D metabolite concentrations were not affected by biological type of cattle (P = 0.21). Muscle VITD concentration was greater (P < 0.05) in Bos taurus-English cattle than in the other two biological types, and muscle 25-OH D concentrations were greater (P < 0.05) in Bos taurus-English cattle than in Bos indicus cattle. Muscle 1,25-(OH)2 D concentration was less (P < 0.05) in the Bos taurus-Continental cattle than in the other two biological types. Cooking eliminated vitamin D metabolite differences among the biological types. Our results suggest that Bos indicus cattle had greater 1,25-(OH)2 D (the biologically active form) in tissues, and greater 1,25-(OH)2 D plasma concentrations than Bos taurus cattle. Thus, the need for VITD supplementation and optimal levels of Ca and P in feedlot diets might differ between Bos indicus and Bos taurus cattle.

Effects of barley variety fed to steers on carcass characteristics and color of meat

This study evaluated the effect of barley varieties in the diets of finishing steers on carcass composition, fat, and lean color and the fatty acid profile of subcutaneous fat. Crossbred steers (391 kg initial BW) were assigned randomly to one of five finishing diets composed primarily of corn (n = 9), Morex barley (n = 9), Steptoe barley, (n = 9), or two experimental barley varieties SM3 (n = 9) and SM5 (n = 9). Grains were cracked prior to feeding. Diets were formulated (DM basis) to be isonitrogenous (2.24% N) and isocaloric (2.01 Mcal/kg NEm and 1.35 Mcal/kg NEg). Steers were slaughtered according to industry-accepted procedures when it was visually estimated that 70% of carcasses would grade USDA Choice. After a 24-h chill at 4 degrees C, carcass quality and yield grade data were collected by trained, experienced university personnel. Objective color (L*, a*, and b*) of both the LM and subcutaneous fat were measured, and samples of subcutaneous fat were removed from the 10th- to 12th-rib region for fatty acid analysis. Diet did not affect hot carcass weight (P = 0.15), fat thickness (P = 0.58), LM area (P = 0.57), percentage of internal fat (P = 0.52), yield grade (P = 0.96), marbling (P = 0.73), or quality grade (P = 0.10). However, the LM from steers fed diets formulated with Morex and SM5 barley varieties tended to be lighter (higher L* values, P = 0.08) than the LM from steers fed the corn-based diet. Additionally, fat from steers fed corn tended to be more yellow (higher Hunter b* values, P = 0.09) than fat from steers fed barley-based diets. Although grain source had only minimal effects on the fatty acid composition of subcutaneous fat samples, pentadecanoic acid (15:0) was greater (P < 0.05) in fat from steers fed SM3 and Steptoe barley varieties than in fat from steers fed corn. Stearic acid (18:0) concentrations were higher (P < 0.05) in fat samples from steers fed corn than in those fed the experimental barley lines (SM3 and SM5). Conversely, fat samples from steers fed Steptoe and SM5 barley had greater (P < 0.05) gadoleic acid (20:1) concentrations than fat from steers fed corn or Morex variety. Although the variety/line of barley included in the finishing diet may affect LM and fat color, grain-source (barley vs. corn) had little effect on beef carcass quality and yield grades and did not greatly alter the fatty acid composition of subcutaneous fat.

Utilization of beef from different cattle phenotypes to produce a guaranteed tender beef product

Cattle (n = 303) were visually selected from four feed yards to represent six phenotypes (English [EN; n = 50], 3/4 English-1/4 Brahman [ENB; n = 52], 1/2 English-1/2 Exotic [ENEX; n = 56], 1/2 English-1/4 Exotic-1/4 Brahman [ENEXB; n = 47], 3/4 Exotic-1/4 Brahman [EXB; n = 49], and 1/2 Exotic-1/4 English-1/4 Brahman [EXENB; n = 49]). Carcasses were processed at a commercial beef packing facility, and strip loins were collected after 48-h chilling. Strip loins were aged for 14 d at 2 degrees C and frozen at -20 degrees C for 3 to 5 d before three 2.5-cm-thick steaks were cut for Warner-Bratzler shear force (WBSF) determinations and sensory evaluations. Phenotype EN had the highest (P < 0.05) adjusted fat thickness, and EXB had adjusted fat thickness that was lower (P < 0.05) than all other phenotypes except EXENB. Carcasses of EN and ENB had smaller (P < 0.05) longissimus muscle areas than phenotypes ENEX, EXB, and EXENB. Phenotype EN produced carcasses with the highest (P < 0.05) numerical yield grade, whereas carcasses originating from phenotype EXB had lower (P < 0.05) numerical yield grades than all other phenotypes except ENEX. No differences (P > 0.05) were found among phenotypes for mean WBSF values or sensory panel ratings for initial and sustained tenderness, initial and sustained juiciness, beef flavor characteristics, and overall mouthfeel. More than 90% of steaks from carcasses of all phenotypes had WBSF values less than 3.6 kg when cooked to an internal cooked temperature of 70 degrees C. Results from this study indicated that all phenotypes represented in this study could be managed to produce tender beef.

Carcass, sensory, and adipose tissue traits of Brangus steers fed casein-formaldehyde-protected starch and/or canola lipid

We predicted that providing rumen-protected starch to the small intestine would increase adiposity of intramuscular adipose tissue, and hence marbling scores. Eighteen 15-mo-old Brangus steers were assigned randomly to one of three dietary treatment groups: 1) cracked corn (Corn); 2) casein-formaldehyde-protected lipid (Canola Lipid); or 3) casein-formaldehyde-protected starch (Marble Plus). All diets were equally balanced for ME (2.91 Mcal/kg), CP (12.5%), and DM (89%). Ether extract was 3.7, 6.9, and 6.9% for the Corn, Canola Lipid, and Marble Plus diets, respectively, and the Marble Plus also contained 3.7% protected starch. Steers were fed the diets for 126 d before slaughter. Average daily feed intake (as-fed basis), ADG, and feed:gain ratio (P > or = 0.23) did not differ among treatments. Carcasses across treatments did not differ (P = 0.26) in adjusted fat thickness, longissimus muscle area, hot carcass weight, dressing percentage, marbling scores, or USDA quality grade. Percentage of kidney, pelvic, and heart fat was higher (P < 0.01) and USDA yield grade tended (P = 0.08) to be higher, for carcasses from Canola Lipid- and Marble Plus-fed steers than for carcasses from Corn-fed steers. Of the descriptive meat sensory attributes, connective tissue amount (P = 0.06) and painty flavor (P = 0.12) tended to be greater in meat from Marble Plus steers than from Canola Lipid steers. Percentages of 18:2n-6 and 18:3n-3 were higher (P < 0.01), and 15:0, 16:0, and 17:0 were lower (P < or = 0.07) in tissues from Canola Lipid- and Marble Plus-fed steers than in Corn-fed steers. Mean adipocyte volume was greater (P = 0.02) in i.m. adipose tissue and tended (P = 0.11) to be greater in s.c. adipose tissue of Canola Lipid steers (848 pL) vs. Corn steers (536 pL). Glucose incorporation into total lipids, glyceride-glycerol, and fatty acid fractions was highest (P < 0.01) in s.c. adipose tissue from steers fed Marble Plus but was unaffected (P > or = 0.33) by diet in i.m. adipose tissue. Fatty acid synthetase activity tended (P = 0.08) to be higher in s.c. adipose tissue of Marble Plus steers, and NADP-malic dehydrogenase activity was higher (P = 0.03) in i.m. adipose tissue of Canola Lipid steers. We conclude that Marble Plus did not improve carcass quality, but also did not reduce beef sensory attributes. Any differences we observed in carcass characteristics, adipose tissue cellularity, or lipogenesis apparently were caused by the protected lipid rather than the protected starch.

A dose-response study of melengestrol acetate on feedlot performance and carcass characteristics of beef steers

The dose response of melengestrol acetate (MGA) on ADG (kg/d) and gain efficiency (gain/DMI, g/kg) was estimated in beef steers fed a finishing diet under commercial feedlot conditions. Melengestrol acetate is not approved for use in steers as a feed additive. The study design was five blocks of four pens (each pen was assigned a dose of MGA) with 166 to 200 steers per pen. Melengestrol acetate was fed to steers at 0 (n = 899, five pens), 0.1 (n = 900, five pens), 0.2 (n = 899, five pens), and 0.4 (n = 900, five pens) mg of MGA/steer daily. Pens within a block were slaughtered on the same day. Blocks 1 through 5 were fed MGA for 123, 122, 116, 124, and 138 d, respectively. The experimental unit was a pen of steers, and blocking was based on source of steers. The ADG was 1.81, 1.85, 1.80, and 1.83 kg/d for steers fed 0, 0.1, 0.2, and 0.4 mg MGA per day, respectively. For ADG, the dose was significant, but neither linear nor quadratic effects were significant. Compared with steers of the control group, ADG was greater for steers fed 0.1 mg MGA (P < 0.01). Feed efficiencies were 170, 173, 171, and 172 g/kg for steers fed 0, 0.1, 0.2, and 0.4 mg MGA/d, respectively; however, no effects of dose (P = 0.19) or linear (P = 0.21) or quadratic (P > 0.60) effects were observed. There was no evidence for either positive or negative effects of MGA on DMI, hot carcass weight, dressing percent, quality grade, yield grade, back fat thickness, marbling score, longissimus muscle area, and incidence of dark cutter carcasses in response to feeding MGA to steers at doses of 0.1, 0.2, and 0.4 mg daily. The incidence of buller behavior (0.43 to 1.11%) was low and did not permit an accurate test of the clinical observations that feeding MGA to steers decreases the occurrence of buller steers. Melengestrol acetate fed to finishing beef steers produced small improvements in growth performance (ADG, 2.2%) at the 0.1 mg MGA dose, but none of the doses examined produced improvement in carcass quality or yield grade measurements.

Relationships of consumer sensory ratings, marbling score, and shear force value to consumer acceptance of beef strip loin steaks

Logistic regression was used to quantify and characterize the effects of changes in marbling score, Warner-Bratzler shear force (WBSF), and consumer panel sensory ratings for tenderness, juiciness, or flavor on the probability of overall consumer acceptance of strip loin steaks from beef carcasses (n = 550). Consumers (n = 489) evaluated steaks for tenderness, juiciness, and flavor using nine-point hedonic scales (1 = like extremely and 9 = dislike extremely) and for overall steak acceptance (satisfied or not satisfied). Predicted acceptance of steaks by consumers was high (> 85%) when the mean consumer sensory rating for tenderness,juiciness, or flavor for a steak was 3 or lower on the hedonic scale. Conversely, predicted consumer acceptance of steaks was low (< or = 10%) when the mean consumer rating for tenderness, juiciness, or flavor for a steak was 5 or higher on the hedonic scale. As mean consumer sensory ratings for tenderness, juiciness, or flavor decreased from 3 to 5, the probability of acceptance of steaks by consumers diminished rapidly in a linear fashion. These results suggest that small changes in consumer sensory ratings for these sensory traits have dramatic effects on the probability of acceptance of steaks by consumers. Marbling score displayed a weak (adjusted R2 = 0.053), yet significant (P < 0.01), relationship to acceptance of steaks by consumers, and the shape of the predicted probability curve for steak acceptance was approximately linear over the entire range of marbling scores (Traces67 to Slightly Abundant97), suggesting that the likelihood of consumer acceptance of steaks increases approximately 10% for each full marbling score increase between Slight to Slightly Abundant. The predicted probability curve for consumer acceptance of steaks was sigmoidal for the WBSF model, with a steep decline in predicted probability of acceptance as WBSF values increased from 3.0 to 5.5 kg. Changes in WBSF within the high (> 5.5 kg) or low (< 3.0 kg) portions of the range of WBSF values had little effect on the probability of consumer acceptance of steaks.

Creatine monohydrate supplemented in swine finishing diets and fresh pork quality: III. Evaluating the cumulative effect of creatine monohydrate and alpha-lipoic acid1,2

The objective of this study was to evaluate short-duration supplementation of alpha-lipoic acid (ALA) and creatine monohydrate (CMH) to improve fresh pork quality. Forty-eight commercial hybrid barrows were blocked by BW and randomly allotted to one of four treatments: 1) no CMH or ALA; 2) supplementation of 24 g of CMH(-1) x pig(-1) x d(-1); 3) supplementation of 600 mg ALA(-1) x pig(-1) x d(-1); or 4) combined CMH and ALA supplements. Twelve pigs per treatment were individually penned with ad libitum access to water and a finishing diet. Treatments were hand-fed to individual pigs daily (divided into three equal doses) for 5 d before slaughter at 113 kg BW in two separate groups of 24 pigs each. Intramuscular pH was recorded at 45 min postmortem and again at 24 h in the ham semimembranosus (SM) and the longissimus muscle (LM) between the 10th and 11th rib. A Meatcheck (SFK Technology, Peosta, IA) conductivity probe was inserted in the same anatomical locations as pH measurement, providing an index value (PY) from 0 to 100 (a higher index value indicates more intact muscle cells and higher water-holding capacity). Color (L, a, b values) measurements were obtained at 24 h postmortem on the ham gluteus medius (GM), SM, and LM. Two 2.54-cm-thick loin chops were removed from the loin for determination of Warner-Bratzler shear force and glycolytic potential. The intact SM and the posterior portion of the boneless loin were vacuum-packaged and stored for 7 d to determine purge loss. Creatine-supplemented pigs had a higher (P = 0.03) PY value in the SM (66.67) at 45 min postmortem than either ALA, singularly (63.50), or in the combined CMH/ALA (62.27) treatments. (A higher PY index indicates superior water-holding capacity.) Lipoic acid supplementation resulted in the highest pH at 45 min (P = 0.029). These results justify further evaluation of the potential positive influence of supplementing alpha-lipoic acid to improve pork quality.

Effect of repeated administration of combination trenbolone acetate and estradiol implants on growth, carcass traits, and beef quality of long-fed Holstein steers1

Our objective was to determine the effect of repeated use of implants on feedlot performance and carcass characteristics of Holstein cattle. Holstein steers (n = 128) weighing an average of 211 kg were blocked by weight and randomly assigned to 16 pens. At the start of the trial (d 0), pens were assigned to one of four treatments: 1) nonimplanted control (C); 2) implant on d 0, 112, and 224 (T3); 3) implant on d 112 and 224 (T2); and 4) implant on d 224 (T1). Component TE-S implants (120 mg of trenbolone acetate and 24 mg of estradiol per implant) were used for all treatments during the 291-d feeding period. Over the course of the study, T2 and T3 cattle had greater ADG and final weights than C and T1 cattle (P < 0.05). Steers were harvested at a commercial abattoir on d 291. Hot carcass weights of T3 steers were greater than those of C and T1 steers (P < 0.05). Dressing percentage, adjusted 12th-rib fat, percentage of kidney, pelvic, and heart fat, yield grade, and longissimus color were not different among treatments (P > or = 0.26). Longissimus muscle areas (LMA) of T2 and T3 carcasses were larger than LMA of C (P < 0.01). No USDA Select carcasses were produced from C cattle, whereas the percentage of Select carcasses from implanted cattle ranged from 10 to 18%. Skeletal maturity advanced (P < 0.05) progressively with each additional implant. Steaks from T3 carcasses had a higher percentage of protein than controls (P < 0.05) and were less tender than all other treatments (P < 0.05). Repeated administration of combination trenbolone acetate and estradiol implants increased ADG and resulted in heavier carcasses with larger LMA. Administration of three successive implants decreased tenderness of Holstein beef, and resulted in more advanced skeletal maturity scores.

Real-time augmentation of USDA yield grade application to beef carcasses using video image analysis

In two phases, this study assessed the ability of two video image analysis (VIA) instruments, VIASCAN and Computer Vision System (CVS), to augment assignment of yield grades (YG) to beef carcasses to 0.1 of a YG at commercial packing plant speeds and to test cutout prediction accuracy of a YG augmentation system that used a prototype augmentation touchpanel grading display (designed to operate commercially in real-time). In Phase I, beef carcasses (n = 505) were circulated twice at commercial chain speeds (340 carcasses per hour) by 12 on-line USDA graders. During the first pass, on-line graders assigned a whole-number YG and a quality grade (QG) to carcasses as they would normally. During the second pass, on-line graders assigned only adjusted preliminary yield grades (APYG) and QG to carcasses, whereas the two VIA instruments measured the longissimus muscle area (LMA) of each carcass. Kidney, pelvic, and heart fat (KPH) was removed and weighed to allow computation of actual KPH percentage. Those traits were compared to the expert YG and expert YG factors. On-line USDA graders' APYG were closely related (r = 0.83) to expert APYG. Instrument-measured LMA were closely related (r = 0.88 and 0.94; mean absolute error = 0.3 and 0.2 YG units, for VIASCAN and CVS, respectively) to expert LMA. When YG were augmented using instrument-measured LMA and computed either including or neglecting actual KPH percentage, YG were closely related (r = 0.93 and 0.92, mean absolute error = 0.32 and 0.40 YG units, respectively, using VIASCAN-measured LMA; r = 0.95 and 0.94, mean absolute error = 0.24 and 0.34 YG units, respectively, using CVS-measured LMA) to expert YG. In Phase II, augmented YG were assigned (0.1 of a YG) to beef carcasses (n = 290) at commercial chain speeds using VIASCAN and CVS to determine LMA, whereas APYG and QG were determined by online graders via a touch-panel display. On-line grader YG (whole-number), expert grader YG (to the nearest 0.1 of a YG), and VIASCAN- and CVS-augmented YG (to the nearest 0.1 of a YG) accounted for 55, 71, 60, and 63% of the variation in fabricated yields of closely trimmed subprimals, respectively, suggesting that VIA systems can operate at current plant speeds and effectively augment official USDA application of YG to beef carcasses.

Color stability of semitendinosus, semimembranosus, and biceps femoris steaks packaged in a high-oxygen modified atmosphere

The objectives of this study were to evaluate visual and chemical attributes of beefsteaks from various USDA quality grades and muscles packaged in high-oxygen (80% O2/20% CO2) modified-atmosphere packaging (MAP). A total of nine carcasses were selected to represent Select (n = 3), low Choice (n = 3), and high Choice (n = 3) USDA quality grades. The semimembranosus (SM), semitendinosus (ST), and biceps femoris (BF) muscles were removed from each carcass and allotted to two packaging types (MAP or polyvinyl chloride over-wrap) and were displayed for up to 10 d, with evaluation on d 1, 3, 5, 7, and 10. Fifty-four steaks were evaluated on each day by a five-member trained panel for visual color (lean color and discoloration) and were also analyzed with a Minolta Chroma Meter CR-310 for L* and a* values (lightness and redness, respectively). Chemical properties measured included percentage of metmyoglobin formation and fat content. Visual color scores did not differ (P > 0.05) at d 1 and 3 with respect to all quality grades, but decreased after d 3, with a greater reduction (P < 0.05) in high Choice steaks for both lean color and discoloration. The low Choice steaks packaged in MAP displayedhigher (P < 0.05) lean color scores and less (P < 0.05) discoloration at d 7 and 10 than did Select and high Choice steaks. Redness (a*) values also decreased (P < 0.05) after d 3, whereas (lightness) L* values declined (P < 0.05) from d 1 to 5. The high Choice steaks had higher (P < 0.05) metmyoglobin content than low Choice and Select steaks, but packaging had no effect (P > 0.05) on metmyoglobin content. Muscle type did affect metmyoglobin content; however, the metmyoglobin content of the SM was greatest (P < 0.05), followed by the BF, with the ST having the lowest (P < 0.05) metmyoglobin formation. Results indicate that low Choice steaks react the best in MAP, and the ST maintained greater storage characteristics regardless of quality grade or packaging.

Accuracy and repeatability of beef carcass longissimus muscle area measurements

This study was conducted to determine the accuracy and repeatability of beef carcass longissimus muscle area (LMA) measurements obtained by three different methods. Longissimus muscle area for beef carcass sides (n = 100) randomly selected in a commercial packing plant was determined: 1) independently by three USDA grading supervisor "experts" using the grid method to obtain triplicate measurements of the same longissimus muscle (LM); 2) by three different Colorado State University personnel tracing the LMA on acetate paper and subsequently measuring the area via a polar planimeter three different times (total of 3 x 3 = 9 observations/LM); and 3) by use of two identical video image analysis (VIA) instruments making triplicate measurements for each LM using three different procedures. Video image analysis Procedure 1 required that LMA be measured by placing the camera head unit over the LM and collecting three sequential images without moving the camera head unit while carcasses were in a stationary position; Procedure 2 required measurement of LMA by placing the camera head unit over the LM and collecting three images, but removing and repositioning the camera head unit between collection of each image while carcasses were in a stationary position; and Procedure 3 required that LMA be measured by placing the camera head unit over the LM and obtaining an image while carcasses were in continuous motion (chain speed of 360 carcasses/ h) during three different circulations past the grading stand. Overall, VIA-derived LMA measurements were highly accurate for all three procedures compared with expert-gridded (R2 = 0.92, 0.90, and 0.84 for Procedures 1, 2, and 3, respectively) and acetate/planimeter-traced (R2 = 0.94, 0.93, and 0.86 for Procedures 1, 2, and 3, respectively) LMA measurements. Instrument LMA repeatability also was comparable to expert-gridded and acetate/planimeter-traced LMA repeatability, as the means of the absolute differences between individual measurements and the average of those same measurements per LM were 1.29, 1.35, 0.52, 0.84, and 1.87 cm2 for expert-gridded, acetate/planimeter-traced, and VIA Procedures 1, 2, and 3, respectively. Therefore, VIA instrumentation can be used to assess beef carcass LMA in both a stationary and operational scenario with high levels of accuracy and repeatability.