Effects of supplementing feedlot steers and heifers with zilpaterol hydrochloride on Warner–Bratzler shear force interrelationships of steer and heifer longissimus lumborum and heifer triceps brachii and gluteus medius muscles aged for 7, 14 and 21 d

Longissimus lumborum (LL) muscles from 117 steers plus LL, gluteus medius (GM), and triceps brachii (TB) muscles from 132 heifers were evaluated for effects of feeding duration of zilpaterol hydrochloride (Zilmax®; ZH; 7.56 g/907 kg on a dry matter basis) and aging time on tenderness. Both genders were blocked by initial weight into six blocks of four pens. Pens were assigned to treatments of control (C), or 20, 30 or 40 days on ZH, with a 3 day withdrawal. Steaks from each subprimal were vacuum aged individually for 7, 14 or 21 days, frozen, thawed, and cooked to 71 °C for Warner–Bratzler shear force (WBSF). All muscles from steers and heifers from ZH30 and ZH40 treatments had higher (P < 0.05) WBSF than those of C. The WBSF of steer LL and heifer TB from the ZH20 treatment was higher (P < 0.05) than C. There was a treatment by aging interaction (P > 0.05) for WBSF of GM steaks from heifers. Percentage of intramuscular fat had little effect on tenderness. Percentages of steer LL and heifer TB steaks with WBSF values below thresholds of either 5.0 or 4.6 kg from the ZH20 treatment were quite high, whereas percentages of heifer LL and GM muscles below 5.0 kg (67%) and 4.6 kg (57%) were low. Feeding ZH ? 20 days generally increased WBSF values, but mean WBSF values for steer LL and heifer TB were below 4.6 kg. Feeding ZH 20 ? days resulted in >40% of GM steaks with WBSF values above 4.6 kg.     

Consumer responses for tenderness and overall impression can be predicted by visible and near-infrared spectroscopy,Meullenet–Owens razor shear,and Warner–Bratzler shear force

Beef ribeye rolls (n = 40) from Select, low Choice, top (upper 2/3) Choice, and Prime quality grade carcasses were used to determine the relationship of visible and near-infrared spectroscopy (VNIR) reflectance, Warner–Bratzler shear force (WBSF), and Meullenet–Owens razor shear (MORS) with consumer responses for tenderness and overall impression. Steaks (2.54 cm) were cut and assigned to either 14 or 28 d aging (n = 4/aging period). Reflectance in the VNIR spectrum was measured 1 d from the box-date no less than 30 min after cutting, and prior to aging. The steak used for VNIR measurement was designated for WBSF and MORS measurement, whereas three adjacent steaks were cooked for evaluation by a consumer panel (n = 240 members). Steaks from the Select-grade ribeye rolls had the greatest (P = 0.06) WBSF values and lower (P < 0.05) overall impression scores than those from top Choice and Prime quality grades. Consumer panelists evaluated steaks aged 28 d as more tender (P < 0.05) than those aged 14 d. The relationship of mechanical tenderness measurements were higher with consumer panel responses for tenderness than with overall impression, and those relationships were stronger for the Select grade than for quality grades with higher degrees of marbling. The 2nd derivatives of VNIR measurements were more successful at predicting consumer panel responses of tenderness and overall impression than WBSF and MORS; thus, VNIR methodology was less invasive and more predictive than other, more traditional tenderness measurements.     

Effects of blade tenderization,aging method and aging time on meat quality characteristics of Longissimus lumborum steaks from cull Holstein cows

The effects of blade tenderization (BT), two aging methods (dry (D) and wet (W)), and aging time (2 and 23 d) on tenderness, color, and sensory properties of Longissimus lumborum muscles from 12 cull Holstein cows were evaluated. Dry-aged loins had higher combined trim and aging losses than control (C) for both D- and W-aging, mostly because of excess trim losses. BT steaks had WBSF of 33.13 N while C steaks had WBSF of 41.46 N (P = 0.09). Aging decreased WBSF. Blade tenderized steaks had higher cook loss than C steaks. Aging, W-aging, and BT × W-aging improved myofibrillar (sensory) tenderness scores. Aging and/or BT improves sensory panel tenderness cull cow Longissimus lumborum steaks. Aging and blade tenderization combined can increase tenderness and value of Longissimus steaks from cull Holstein cows.     

Color stability and tenderness variations within the gluteus medius from beef top sirloin butts

Beef top sirloin butts (n = 48) from USDA quality grade (QG; upper 2/3 US Choice vs. US Select) and yield grade categories (YG; 1 and 2 vs. 4 and 5) were aged 14 days, GM steaks were cut, with 2 steaks removed from the anterior (ANT), middle (MID) and posterior (POST) sections of the GM. One steak from each section was cut into lateral (LAT), central (CENT) and medial (MED) portions, packaged aerobically, and displayed for 7 days, whereas the second steaks were cooked to 71 °C for WBSF. Top Choice-steaks were redder and more yellow (P < 0.05) than Select steaks during display. Cooking losses were greatest (P < 0.05) in the MED, and least (P < 0.05) in the CENT, portions of GM steaks. Neither QG nor YG category affected WBSF, but differences within the GM were found for (P < 0.05) WBSF. Results of this experiment indicate tenderness and color stability gradients exist within the GM.     

Evaluation of feedlot cattle working chute behavior relative to temperament,tenderness, and postmortem proteolysis

The objective was to investigate if the association between working chute behavior and beef tenderness found in our previous study is related to protein degradation and calpain system activity. Crossbred steers (n = 183) allotted to 16 pens were weighed every 28 d. Temperament was evaluated as exit velocity (EV), chute score (CS), and catch score (CAPS). Between 14 and 16 mo of age (606 ± 52 kg), steers were harvested. Strip steaks were collected and aged for 14 d. Subsamples were collected at 36 h and 7 d postmortem and analyzed for calpastatin activity, μ-calpain autolysis, and troponin-T degradation. Shear force (WBSF) was correlated (P < 0.05) with calpastatin activity and measurements of troponin-T. Calpastatin activity, μ-calpain autolysis, and troponin-T measurements did not correlate with the measurements of EV, CS, and CAPS. Therefore, activation of the calpain system or differences in protein degradation did not appear to influence the differences in tenderness that are correlated with working chute behavior.     

Effect of ractopamine–HCl supplementation for 28 days on carcass characteristics,muscle fiber morphometrics,and whole muscle yields of six distinct muscles of the loin and round

This study evaluated the effects of ractopamine–HCl (RAC) supplementation on carcass characteristics, muscle fiber morphometrics, and tenderness. Thirty-four steers (2 groups, 4 replicates) were fed RAC or carrier for 28 days prior to harvest. Seventy-two hours postmortem, the Longissimus lumborum (LL), Gracilis (GRA), Vastus lateralis (VL), Rectus femoris (RF), Semimembranosus (SM), and Adductor (ADD) were dissected from each carcass. Commodity weight, denuded weight, and muscle dimensions were collected. RAC supplementation tended to affect dressing percentage (P = 0.15) and muscle firmness (P < 0.15), and significantly affected lean maturity (P < 0.05) and marbling score (P < 0.05). With the exception of the LL and GRA (P < 0.05), RAC had no effect on muscle dimensions. RAC did not influence the tenderness of vacuum-packaged, aged steaks as measured by Warner–Bratzler shear force. Muscle fiber size within the six muscles was unchanged (P > 0.05) by RAC. Thus, RAC improves carcass parameters without a negative impact on tenderness.     

Potential mechanisms of carbon monoxide and high oxygen packaging in maintaining color stability of different bovine muscles

The objectives were to compare the effects of packaging methods on color stability, metmyoglobin-reducing-activity (MRA), total-reducing-activity and NADH concentration of different bovine muscles and to explore potential mechanisms in the enhanced color stability by carbon monoxide modified atmosphere packaging (CO-MAP, 0.4% CO/30% CO₂/69.6% N₂). Steaks from longissimus lumborum (LL), psoas major (PM) and longissimus thoracis (LT) packaged in CO-MAP, high-oxygen modified atmosphere packaging (HiOx-MAP, 80% O₂/20% CO₂) or vacuum packaging were stored for 0 day, 4 days, 9 days, and 14 days or stored for 9 days then displayed in air for 0 day, 1 day, or 3 days. The CO-MAP significantly increased red color stability of all muscles, and especially for PM. The PM and LT were more red than LL in CO-MAP, whereas PM had lowest redness in HiOx-MAP. The content of MetMb in CO-MAP was lower than in HiOx-MAP. Steaks in CO-MAP maintained a higher MRA compared with those in HiOx-MAP during storage. After opening packages, the red color of steaks in CO-MAP deteriorated more slowly compared with that of steaks in HiOx-MAP.     

Effects of Electrical Stimulation on Carcass Quality and Meat Palatability Traits of Charolais Crossbred Bulls and Steers

Forty-four Charolais crossbred bulls and steers from a similar background and fed commercially were slaughtered and the right side of each carcass was electrically stimulated. Electrical stimulation reduced lean maturity scores (bulls and steers) and, for steers, lowered lean firmness scores (softer lean) and improved “heat-ring” scores. Electrical stimulation significantly improved most tenderness measurements on steaks from young bulls, but was only effective in decreasing shear force values of steaks from steers. Electrical stimulation was more effective in improving the tenderness of steaks from bulls than those from steers.     

THE EFFECTS OF FEEDING ELEVATED LEVELS OF VITAMINS D3 AND E ON BEEF QUALITY

Yearling (12 Angus, 12 Wagyu ≥ Angus) and 2-year old heifers (12 Angus, 12 Wagyu ≥ Angus) were fed elevated levels of Vitamin D ₃ and/or Vitamin E to evaluate beef quality. Warner-Bratzler shear force (WBS) and sensory characteristics were determined on steaks from the Longissimus lumborum (LL) aged 21 days and on steaks from the Gluteus medius (GM) and Psoas major (PM) aged 7 days. Steaks were cut from all muscles, displayed for 5 days then L * value and hue angle were determined. Vitamin E supplemented heifers received the highest sensory tenderness and juiciness scores, while no differences were observed among other treatments. D ₃+ E supplemented Angus LL had higher WBS values than other treatments and breeds. Display time affected both color measures for all muscles, but especially hue angles of GM and PM. Vitamin treatment affected LL and GM color measures in yearlings to a greater extent than in 2-year olds.     

Quadratic relationship between early-post-mortem glycolytic rate and beef tenderness

Post-mortem (PM) glycolytic rate in beef M. longissimus thoracis et lumborum (LTL) was controlled by applying low-voltage electrical stimulation (ES) for 1 min at different stages along the slaughter line. The ES treatments were as follows: (1) No electrical stimulation (NES); (2) 75 V to one side of the carcass immediately after splitting; (3) 20-40 V during exsanguination; (4) 75 V either during or following exsanguination. The study utilized 40 bulls and 40 steers. Loin steaks were aged in vacuum pouches 2, 4, 8 and 16 days PM. Quadratic equations utilizing pH at 3 h (pH(3)) gave the best estimate of Warner-Bratzler (WB) shear force for 2, 4, 8 and 16 day steaks. The rate of glycolysis is the primary determinant of LTL tenderness in this study. Temperature may only be important through its influence on early PM glycolytic rate. Optimum tenderness was produced by stimulating carcasses or sides to produce a pH(3) of 6·0. ES application to the carcass either just before or after splitting (treatment 2) produced more desirable and consistent pH(3) responses than either NES or ES during exsanguination. Aging has a differential effect whereby the WB shear values from tougher (leaner bulls) 2 day steaks improve to a greater degree, so they are not different from more tender (fatter steers) steaks by 16 day PM.     

Tenderness profiles of ten muscles from F1 Bos indicus x Bos taurus and Bos taurus cattle cooked as steaks and roasts

Twenty Bos taurus (Hereford x Angus crosses) and 20 F1 Bos indicus x Bos taurus heifers of the same age, management and feeding regimen, were harvested and evaluated at 2 days postmortem for carcass and meat traits. Ten muscles were obtained from the right sides and aged until 10 days postmortem. Bos indicus carcasses were lighter, had less fat cover, smaller ribeyes, and less intramuscular lipid (all p ≤ 0.05). Bos taurus longissimus lumborum, gluteus medius, triceps brachii, and semimembranosus muscles cooked as steaks and roasts had a lower Warner-Bratzler shear force (WBSF) (p ≤ 0.05) than those from Bos indicus. Bos taurus deep pectoral and semitendinosus muscles cooked as roasts had a lower WBSF (p < 0.05) than Bos indicus. Infraspinatus, longissimus lumborum, and semitendinosus muscles were more tender (p < 0.05) as roasts than steaks, whereas the opposite was true for the deep pectoral and semimembranosus muscles. Seven of the 10 muscles had lower WBSF (p ≤ 0.05) for Bos taurus when cooked as steaks, roasts or both.     

Palatability characteristics of loin steaks from Charolais crossbred bulls and steers

Loins from 1/2-blood or 3/4- to 7/8-blood Charolais bulls (n = 60) and steers (n = 64) were obtained at 24 h post mortem from electrically stimulated sides and, at 12 days post mortem, steaks were removed and frozen. Shear force values were higher (P < 0·001) and sensory panel evaluations of tenderness and overall palatability were lower (P < 0·001) for steaks from bulls than from steers. No differences (P > 0·05) in connective tissue amount or off-flavour were detected for steaks from bulls versus steers. Significant correlations between carcass secondary sex characteristics and sensory panel evaluations of tenderness were noted, but the coefficients were not of a magnitude to be considered predictive of tenderness.     

Effect of low voltage electrical stimulation on protein and quality changes in bovine muscles during postmortem aging

This experiment was conducted to determine the influence of low voltage electrical stimulation (ES) on the tenderness development of beef round muscles. Eight steers were slaughtered, and ES applied to one side of each carcass within 90 min of exsanguination. Steaks from M. longissimus dorsi, semimembranosus, adductor, and gracilis were vacuum packaged and aged at 4 °C for 9 d. Star probe, sensory evaluation, Western blot assays of troponin-T and μ-calpain autolysis and 2D-DIGE were conducted. ES resulted in accelerated (P < 0.05) pH decline of the longissimus in the first 24 h postmortem. ES did not influence (P > 0.05) proteolysis and tenderness, but did alter the predominance of metabolic proteins in the soluble fraction of muscle. Aging for 9 d improved tenderness (P < 0.05). The data confirmed that low voltage ES at 90 min of exsanguination had no effect on proteolysis and tenderness development in the longissimus dorsi, semimembranosus, adductor or gracilis in beef.     

The comparison of three β-agonists for growth performance,carcass characteristics and meat quality of feedlot cattle

Forty-eight Bonsmara steers were assigned to three treatment groups and one control group consisting of 12 animals each. The control (C) received no β-agonist, while the three treatment groups received zilpaterol (6 ppm) (Z), ractopamine (30 ppm) (R) or clenbuterol (2 ppm) (Cl) for the last thirty days on feed. Growth performance (final 30 days), USDA quality and yield grades and meat quality (shear force, chemical, histological and biochemical) were compared for the three β-agonist and control groups. Animals responded negatively to Cl treatment during initial stages of supplementation, which was evident in lower feed consumption and initial growth rates. For carcass growth and yield, Cl had greater and more efficient growth rates, higher dressed out yields (proportional), lower USDA yield grades, and reduced marbling compared with C (P < 0.05). For meat quality measurements, the M. longissimus (LL) and M. semitendinosus (ST) were sampled. Cl had the greatest effect (P < 0.05) on WBSF, especially on the LL, followed by Z. Variation in tenderness and ageing effects corresponded with variation in calpastatin activity and myofibrillar fragmentation between treatment groups. While zilpaterol and ractopamine are currently the only products registered for cattle in different countries, it seems that zilpaterol has an advantage in carcass growth efficiency and yield without showing any adaptation problems for animals such as experienced by the more aggressive β-agonist clenbuterol.     

EFFECTS OF LATE CASTRATION AND FEEDING TIME ON BOVINE MUSCLE QUALITY

Hereford bulls were late castrated by emasculation at approximately 1 year old or left intact, and fed for 0, 60 or 90 days before slaughter to evaluate various traits of the M. longissimus. More days on feed resulted in increased carcass weight, fat thickness, USDA quality grade, ribeye area and percentage kidney, pelvic and heart fat, with no difference from late castration. Percentage of soluble collagen was highest for M. longissimus steaks from the 60 day feeding group, and lowest among those fed 90 days. Steaks from the controls were lighter colored while those from steers fed 60 days were the most red. No sensory differences occurred except for off-flavor.     

Nitrite-embedded packaging film effects on fresh and frozen beef color development and stability as influenced by meat age and muscle type

Muscles (Longissimus lumborum, LL; Psoas major, PM, semitendinosus, ST) were aged (2, 9 d postmortem), cut into steaks, anaerobically packaged (nitrite-embedded film, NEF), and displayed (fresh, 19 d; frozen, 39 d). Fresh NEF increased (P < 0.05) in redness (first 48 h). Upon opening fresh NEF (d 6) and overwrapping in PVC film, redness declined (P < 0.05). NEF cooked LL had more red surface compared to non-NEF. Meat age influenced NEF color. Intact NEF maintained acceptable red color throughout display. Residual nitrite and nitrate associated with fresh NEF and nitrate in NEF cooked LL were found (P < 0.05) in the outer layer. Consideration should be given to providing sufficient time for nitric oxide myoglobin development when using NEF which may be influenced by meat age and muscle differences. NEF packaging has potential to extend fresh beef color display life. NEF appears to offer the opportunity to display bright red beef in frozen display by limiting typical effects of photooxidation.     

The influence of forage diets and aging on beef palatability

To investigate the influence of diet and aging on beef palatability, lipid oxidative stability, and fatty acid composition, crossbred steers were assigned to Feedlot S (alfalfa and grain), Forage TR (triticale and annual ryegrass), Forage TK (triticale and kale), or Forage + Feedlot (grazing ryegrass, fescue and orchardgrass, finished on alfalfa and grain) dietary treatments. Heifers were finished on Feedlot H (alfalfa and grain). Longissimus and tricep muscles were sampled from these animals for steaks and ground beef, respectively. Steaks were either dry- or wet-aged for 14 d. Ground beef was dry-aged, wet-aged for 14 d, or not aged. Trained sensory panelists evaluated palatability attributes of steaks and ground beef. Diet did not influence sensory attributes of steaks or ground beef. Aging impacted (P < 0.05) sensory attributes of ground beef. Diet and aging had no impact on lipid oxidative stability but affected fatty acid composition of raw ground beef.     

The effects of high oxygen modified atmosphere packaging on protein oxidation of bovine M. longissimus dorsi muscle during chilled storage

Modified atmosphere packaging (MAP) extends the shelf life of beef, especially in the context of visual colour. High O₂ MAP (70-80%) may cause quality deterioration through lipid and protein oxidation, the latter linked to a reduction in meat tenderness. The objective of this study was to investigate the effects of MAP in comparison to vacuum packaging (VP) on protein oxidation and subsequent tenderness of LD (M. longissimus dorsi) beef steaks during chilled storage (4 °C) of periods up to 14 days. Steaks were analysed for carbonyl content, free thiol groups, drip loss, Warner-Bratzler shear force (WBSF) and SDS-PAGE of extracted myofibrillar proteins. Free thiol groups were lower in high O₂ MAP (80% O₂/20% CO₂) steaks, after 14 days of storage, indicating protein oxidation compared to VP steaks. SDS-PAGE (non reducing conditions) showed the presence of high molecular weight cross linked myosin heavy chain aggregates in the high O₂ atmosphere packaged steaks, which were absent in VP steaks.     

Tenderness of major muscles from three breed-types of cattle at different times-on-feed

Seventy-five steers (9 to 12 months of age) of Angus (n = 25), Brahman (n = 25) and Brahman × Angus (n = 25) breed-types of known history were fed a high-energy diet and five steers from each breed-type were slaughtered after 0, 56, 112, 168 and 224 days on test. At seven days post mortem, the left side of each carcass was fabricated and eight major primals or subprimals were obtained. Steaks were removed from the shoulder clod, strip loin, tenderloin, top sirloin, knuckle, top round, bottom round and eye of round for Warner-Bratzler shear (WBS) determinations and from the strip loin and bottom round for sensory panel evaluations. Steaks from Angus and Brahman × Angus steers were generally more tender than steaks from Brahman steers. Tenderness of steaks from steers of the three breed-types responded to time-on-feed differently: (a) steaks from Brahman steers improved (P < 0·05) in tenderness with increasing time-on-feed for all muscles except the M. psoas major (tenderloin); (b) with the exception of the M. longissimus muscle (strip loin), the tenderness of steaks from Angus steers did not change (P > 0·05) as time-on-feed increased and (c) for the Brahman × Angus steers, five of the ten muscles studied improved (P < 0·05) in tenderness with increasing time-on-feed. 'Acceptable' tenderness (WBS values of less than 4·5 kg) for most of the muscles was achieved at feeding periods from 112 to 224 days for Brahman, from 0 to 56 days for Angus and from 56 to 168 days for Brahman × Angus.     

Effects on performance and carcass and meat quality attributes following immunocastration with the gonadotropin releasing factor vaccine Bopriva or surgical castration of Bos indicus bulls raised on pasture in Brazil

Bos indicus bulls 20 months of age grazed on pasture in Minas Gerais, Brazil either received 2 doses of the GnRF vaccine Bopriva at d0 and d91 (group IC, n = 144) or were surgically castrated on d91 (group SC, n = 144). Slaughter on d280, was 27 weeks after castration. Adverse safety issues in 8% of group SC bulls following surgery contrasted with 0% in group IC bulls. At d105 testosterone levels were suppressed to similar levels in both groups. Importantly, group IC bulls had higher live weight, hot carcass weight, ADG (P < 0.005) and dressing percentage (P < 0.0001) compared to group SC animals. There were no negative effects on carcass or meat quality traits, thus immunocastration was concluded to offer a safe and effective method that provides production gains, and improves animal welfare in Bos indicus beef bulls without impacting meat and carcass quality.