USDA Choice Grade Research Articles

Effects of beef production system on animal performance and carcass characteristics.

The objective of this study was to evaluate conventional (CONV) and natural (NAT) beef production systems from annual pasture through finishing through grazing. Beef steers (n=180, initial BW=250±19 kg) were assigned randomly to 2 treatments in the pasture phase. Steers were implanted with 40 mg of trenbolone acetate (TBA), 8 mg estradiol, and 29 mg tylosin tartrate (CONV), or received no implant (NAT). Steers on the 2 treatments grazed wheat or cereal rye for 109 d. Conventional steers had an 18.5% improvement in ADG (1.22 vs. 1.03 kg/d, P<0.01) and a heavier final BW (385 vs. 366 kg, P<0.01) compared with NAT steers. Following the pasture phase, steers (n=160 steers, 5 steers/pen, 8 pens/treatment) were assigned to a 2×2 factorial in the feedlot phase. Production system (NAT vs. CONV) was maintained from the pasture phase, and the second factor was 7 vs. 12% low-quality roughage (DM basis, LOW vs. HIGH). During finishing, CONV steers were given 120 mg of TBA and 24 mg estradiol at processing, fed monensin and tylosin, and fed zilpaterol hydrochloride for the last 20 d of the experiment. There were no program×roughage level interactions (P>0.07). The CONV steers ate 6.9% more feed (11.8 vs. 11.0 kg/d, P<0.01), gained 28.4% faster (1.90 vs. 1.48 kg/d, P<0.01), and were 24.2% more efficient (0.164 vs. 0.132, P<0.01) compared with NAT steers. The LOW steers had greater G:F (0.153 vs. 0.144, P<0.01) compared with HIGH steers. There was a 28.3% improvement in estimated carcass weight gain (1.36 vs. 1.06 kg/d), 18.6% improvement in carcass efficiency (0.115 vs. 0.097, P<0.01), and 21.6% improvement (1.52 vs. 1.25 Mcal/kg, P<0.01) in calculated dietary NEg for CONV compared with NAT steers. Hot carcass weight was increased by 62 kg (424 vs. 362 kg, P<0.01) and LM area was increased by 16.9 cm2 (100.9 vs. 84.0 cm2, P<0.01), decreasing USDA yield grade (YG, 3.09 vs. 3.54, P<0.01) for CONV steers compared with NAT steers. Natural steers had a greater percentage of carcasses in the upper 2/3 of USDA Choice grade (48.7 vs. 18.7%, P<0.01), a greater percentage of YG 4 and 5 carcasses (25.4 vs. 9.3%, P<0.01), and a greater percentage of abscessed livers (39.6 vs. 10.5%, P<0.01) compared with CONV steers. The results show that CONV production results in more rapid and efficient production that resulted in heavier carcasses with superior YG and desirable quality grades with both roughage levels.

Characteristics and hedonic pricing of differentiated beef demands

AbstractWe estimate a CBS system model of U.S. derived demand for meat. We use this model (1) to examine relationships between three quality categories of beef and three other meats and (2) to simulate how taste shifts have affected demands for meats over time. We extend previous studies by disaggregating wholesale beef production into three quality categories: (1) USDA Choice grade or higher, (2) USDA Select or lower, and (3) cow and bull beef. Innovative features of our empirical model include a breakout of ‘table cuts’ into Choice and Select and the use of a hedonic characterization of the two breakouts to value “Choice‐ness” and “beef‐ness.” Our model demonstrates important shifts in separate demands for Choice and Select beef. We show that, separately, the demand for Choice‐grade beef declined in the 1980s and 1990s and the demand for Select beef increased, a departure from the relatively stable demand characterizations of more aggregated measures of combined Choice and Select beef.

The effects of quality grade, aging, and location within muscle on Warner–Bratzler shear force in beef muscles of locomotion

Aging patterns of nine muscles from the chuck and round from two quality classifications of beef: USDA Select and upper 2/3 of USDA Choice grade were determined. The following muscles were evaluated: infraspinatus, triceps brachii – lateral head, triceps brachii – long head, serratus ventralis, complexus, splenius, rhomboideus, vastus lateralis and rectus femoris. Muscles were divided into four portions, progressing from anterior to posterior or dorsal to ventral orientation to the carcass depending on muscle fiber orientation. One steak was removed from each portion and aged for 7, 14, 21, or 28 d postmortem, then Warner–Bratzler shear force (WBSF) analysis was conducted. Consistent aging recommendations can be given for all muscles studied, as there was no aging by muscle interaction. An aging by USDA grade interaction was noted ( P < 0.05). The upper 2/3 of USDA Choice need not be aged beyond 7 d. USDA Select should be aged at least 14 d. Steak location within muscle had an effect ( P < 0.05) on WBSF values in four muscles. These data indicate that fabrication and merchandizing decisions should be made on an individual muscle basis.

Effects of postmortem aging period and blade tenderization on sensory traits of beef steaks (2000)

We used 54 strip loins, 54 top sirloin butts, and 54 inside rounds, all USDA Choice grade, to determine the influence of different postmortem aging periods and blade tenderization passes on sensory panel traits. Cuts were aged for 7, 14, or 21 days and not tenderized (0X) or blade tenderized one (1X) or two (2X) times. All steaks were cooked to 160°F internally, and samples were evaluated by a trained sensory panel for flavor intensity, juiciness, myofibrillar tenderness, connective tissue amount, and overall tenderness. Both longer aging periods and blade tenderization passes improved tenderness of strip loin and top sirloin butt steaks without affecting either flavor or juiciness, but did not affect tenderness of top round steaks. Therefore, meat purveyors should use these technologies to improve tenderness and consistency of strip loin and top sirloin butt steaks. (

Effects of Lactation and Prenatal Androgenization on the Performance, Carcass Composition, and Longissimus Muscle Sensory Characteristics of Heifers in the Single-Calf Heifer System

Two experiments were conducted to evaluate feedlot performance, lactational characteristics, and carcass composition and quality of heifers and the performance of their calves in a single-calf heifer (SCH) system. In Exp. 1, 13 [10 lactating (L) and 3 nonlactating (NL)] prenatally androgenized (PA) heifers, born to cows implanted with testosterone propionate (TP) and 19 (13L and 6 NL) control (C) heifers, born to nonimplanted cows, were used. Heifers were calved and the pairs were placed in feedlot pens to evaluate the effects of PA on feedlot performance and lactation. Heifers were fed an 85% concentrate diet and fed to a compositional endpoint of 1.1cm of subcutaneous fat cover, at which point calves were weaned and heifers slaughtered approximately 12h later. The NL heifers consumed 17.0% less (P<0.01) dry matter and were 30.8% more (P<0.01) efficient in feed conversion. When calf performance was included, overall feed efficiency of L heifers was 26.9% greater (P<0.05; 0.151 vs 0.119) than that of the NL feedlot heifers. Prenatal androgenization had no effect on heifer performance. Four percent fat-corrected milk yield averaged 7.79 and 5.62 kg/d for PA and C heifers, respectively. The NL heifers had 11.0% greater (P<0.01) marbling score and yield grades were 3.77 and 3.03 (P<0.05) for NL and L heifers, respectively. Livers (P<0.01) and kidneys (P<0.05) as a percentage of shrunk weight were heavier for L heifers than for NL heifers. Two carcasses were classified as hard-boned (C-maturity) and 74% received a USDA Choice grade. The L heifers tended (P<0.10) to have lower taste panel tenderness scores; however, shearforce was similar (P=0.81) for L and NL heifers. In Exp. 2, 24 Angus × Holstein heifers were utilized in the single-calf heifer system, similar to Exp. 1. Calves were weaned from their dam between d 64 and 89 postpartum. Heifers that had their calves early weaned (EW) gained 44.2% faster (P<0.01) and consumed 10.8% less (P<0.05) DM than L heifers. The EW heifers were 60.0% more (P<0.01) efficient than L heifers. However, when calf performance was included with heifer performance, L heifers were 23.7% more (P<0.05) efficient than EW heifers. The EW heifers had 18.9% heavier (P<0.01) hot carcasses than L heifers. Backfat thickness was 1.07 and 0.66cm (P<0.01) for the EW and L heifers.

USE OF GRILLING AND COMBINATION BROILER-GRILLING AT VARIOUS TEMPERATURES FOR BEEF LOIN STEAKS DIFFERING IN MARBLING

Beef loins from 10 carcasses of Small minus marbling (USDA Select grade) and 10 carcasses of Slight minus marbling (USDA Choice grade) were used in the study. Steaks were cooked to 67C by either simultaneous broiler-grilling or by grilling alone. Temperature settings during cooking of either 204 or 232C were used in each cooking system. Broiler-grilled steaks took less time to reach 67C, but also had more cooking loss and a more well-done appearance. These results were most likely influenced by the higher cooking temperature around steaks subjected to broiler-grilling compared to grilling, regardless of temperature setting. Steaks cooked by grilling were more tender by both sensory and shear force measurements compared to steaks cooked by broiler-grilling. Grilling produced higher juiciness scores than broiler-grilling, but only at the 232C setting. However, temperature control settings did not influence cooking loss and degree ofdoneness. Higher sensory ratings for tenderness were found for Small minus steaks compared to Slight minus steaks. While both systems of cooking appear suitable for producing acceptable eating quality in steaks of low marbling, the grilling method seems preferable. Grilling, probably because of its slower cooking time, provides advantages in tenderness, juiciness and cooking yield with perhaps a more uniform and consistent cooking rate.

Effects of a Beef Grade Change on Choice and Select Slaughter Cattle Prices

AbstractDistributed lags are used to estimate the conditional price effects of quality grade substitution and ungraded beef on USDA Choice and Select grade slaughter cattle. The results show that Choice beef production and ungraded production demonstrate large class price effects. When revising USDA Choice grade to accommodate reduced marbling, potential reclassification of ungraded beef plays a major role. The results show a decrease in Choice price with a slight increase in Select price and a reduction in the price premium paid for Choice steers. Overall, grade modifications emphasizing leaner beef would not necessarily benefit cattle producers unless there was a compensating change in demand and/or a reduction in feeding costs.

THE INFLUENCE OF DELAY CHILLING AND HOT BONING ON TENDERNESS OF BOVINE MUSCLE

ABSTRACTThe removal of muscle and muscle systems before initial chilling of the bovine carcass has been investigated in recent years to determine the feasibility of this processing method as a future alternative to conventional fabrication. One important consideration relating to the delay chilling process is the tenderness attribute of eating quality. This investigation was initiated to examine meat tenderness as related to three delay chilling periods. Twelve USDA choice grade Angus steer carcasses were assigned at random to three holding periods. One side of each carcass was randomly assigned to be delay chilled at 16°C for 3, 5 or 7 hr before fabrication into muscle and muscle systems. The remaining side was likewise processed into muscle and muscle systems following chilling at l.l°C for 48 hr. Meat tenderness was objectively estimated by the use of the Warner‐Bratzler Shear, Nip Tenderometer, and Rotating DuII Knife Tenderometer. Subjective evaluation of meat tenderness was by a trained panel. The muscles utilized in this investigation were the biceps femoris, longissimus dorsi, and semirnembranosus. Differences among shear force and penetration values between chill and delay chill treatments were, small, averaging less than 1.65 kg and 0.18 cm respectively. Shear force and penetration measurements taken by mechanical instruments, therefore led to the conclusion that no major differences attributed to meat tenderness existed between beef fabricated 48 hr postmortem at l.l°C, and that held 3, 5 or 7 hr postmortem at 16°C. Detectable variations registered by the trained tenderness panel were small between the two treatments, supporting the findings indicated by mechanical instruments that the boning of beef 3, 5 or 7 hr postmortem before chilling provides beef of satisfactory tenderness.