Effects of ractopamine hydrochloride (RH) and zilpaterol hydrochloride (ZH) on saleable yield of carcass sides from calf-fed Holstein steers were evaluated using steers implanted with a progesterone (100 mg) plus estradiol benzoate (10 mg) implant followed by a terminal trenbolone acetate (200 mg) plus estradiol (40 mg) implant. Steers were blocked by weight into pens (n = 32) randomly assigned to one of four treatments: control, RH fed at 300 mg•steer(-1)/d(-1) (RH 300) or RH fed at 400 mg•steer(-1)/d(-1) (RH 400) the final 31 d of finishing, and ZH fed at 60 to 90 mg•steer(-1)/d(-1) (7.56 g/ton on a 100% DM basis) for 21 d with a 5 d withdrawal before harvest. Eight to nine carcass sides were randomly selected from each pen; carcass sides with excessive hide pulls, fat pulls or bruises were avoided. Cutout data were collected within a commercial facility using plant personnel to fabricate sides at a rate of one every 3 to 4 min into items typically merchandised by the facility. All lean, fat and bone were weighed and summed back to total chilled side weight with a sensitivity of ± 2% to be included in the data set. Compared to controls, β-agonists increased saleable yield of whole-muscle cuts by 0.61%, 0.86% and 1.95% for RH 300, RH 400 and ZH, respectively (P < 0.05). Percent fat was less in carcasses from the ZH treatment compared to controls (P < 0.05); however, this difference was not observed between RH treatments and controls (P > 0.05). Percent bone was less in the ZH treatment due to increased muscle (P < 0.05). The percent of chilled side weight comprised of trimmings was unchanged between treatments, but on a 100% lean basis, RH 400 and ZH increased trim yields (P < 0.05). Analysis of saleable yield by primal showed a fundamental shift in growth and development. Beta-agonists caused a shift in proportion of saleable yield within individual primals, with a greater portion produced from the hindquarter relative to the forequarter, specifically in those muscles of the round (P < 0.05). Beta-agonists increased saleable yield, but these effects were not constant between all major primals. The cutout value gained by packers as a result of β-agonist use may be influenced more by reduced fatness and increased absolute weight if musculature is primarily increased in the lower priced cuts of the carcass.

This study compared sensory properties of LM steaks from A maturity and B maturity or older carcasses that were produced by grain-finished steers and heifers classified as less than 30 mo old at the time of slaughter using dentition. Carcasses were selected to represent 2 maturity groups and 3 marbling categories within each maturity group, resulting in 6 maturity × marbling subclasses, each subclass consisting of 75 carcasses. Maturity groups consisted of carcasses classified by USDA graders as either A(00) to A(99) overall (A) maturity or B(00) to C(99) overall (B-C) maturity; marbling categories consisted of carcasses with instrument marbling scores of Slight (SL), Small (SM), or Modest(00) or greater (MT+). Carcasses were selected in pairs so that each carcass chosen to represent the B-C maturity group was paired with an A maturity carcass of the same sex and marbling score (± 30 marbling units). Strip loin (LM) steaks were obtained from both sides of each carcass. After a 14-d aging period, 1 LM steak was measured for Warner-Bratzler shear force (WBSF) and slice shear force (SSF), whereas the other LM steak was used for sensory analysis by a trained descriptive attribute panel. No differences (P > 0.05) in WBSF, SSF, or sensory panel ratings for tenderness, juiciness, or flavor were detected between LM steaks from carcasses classified as A maturity and steaks from B-C maturity carcasses. However, marbling categories effectively stratified carcasses (MT+ > SM > SL) according to differences (P < 0.0001) in LM tenderness, juiciness, meaty/brothy flavor, and buttery/beef fat flavor. Increased marbling also was associated with lesser (P < 0.01) intensities of bloody/serumy and livery/organy flavors and reduced (P < 0.01) values for WBSF and SSF. Of the traits tested, only bloody/serumy flavor was affected (P < 0.05) by the maturity × marbling interaction. Interaction means showed that LM steaks from B-C maturity carcasses with SL marbling had a less intense bloody/serumy flavor than did steaks from A maturity carcasses with SL marbling. Results of this study suggest that, when applied to carcasses from grain-finished cattle whose dental ages are less than 30 mo old at the time of slaughter, USDA quality grades would be no less effective in identifying eating quality differences if the A and B-C maturity groups were combined and quality grades were assigned using only marbling.

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NUTRIENT ANALYSIS OF THE BEEF ALTERNATIVE MERCHANDISING CUTSSix carcasses were selected from each of four different beef packing plants.Carcasses were a combination of USDA Yield Grade 2 (n = 12) and USDA Yield Grade 3 (n = 12), US Quality Grade Premium Choice (n = 8), Low Choice (n = 8), and Select (n = 8), and two genders (steer n = 16, heifer n = 8). The four beef packing plants were located in the Midwestern part of the United States: two in Colorado, one in Kansas, and one in Nebraska. Beef Ribeye, Beef Loin, Strip Loin, and Beef Loin, Top Sirloin Butt subprimals were collected from both sides of these carcasses. Subprimals were vacuum packaged and aged for 14 to 21 days at 0 to 4°C. Subprimals were fabricated into the Beef Alternative Merchandising (BAM) cuts, as described by the Beef Innovations Group of the National Cattlemen's Beef Association (NCBA), at Colorado State University Meat Laboratory. Cuts from both sides of the carcass were randomly designated for use in obtaining cooked and raw nutrient data. All cuts were vacuum packaged and stored at -18°C for subsequent cooking and/ or dissection. Raw cuts were thawed at 0 to 4°C for 24 to 48 h and then dissected into separable lean, separable fat, and refuse (connective tissue). Cuts to be cooked were thawed for 24 to 48 h at 0 to 4°C, roasted or grilled, tempered for 24 to 48 h at 0 to 4°C, then dissected into separable lean, separable fat, and refuse. Following dissection, iii both raw and cooked samples were homogenized and then stored at -80°C for subsequent nutrient analysis. The BAM cuts were analyzed for moisture, crude protein, percent lipid, and ash. Of the muscles that comprise the BAM cuts, the Spinalis dorsi contained the highest percent fat and lowest percent moisture. As fat content increased, moisture content subsequently decreased. The muscles from the Top Sirloin Butt were the leanest of the muscles comprising the BAM cuts. Fatty acid composition and cholesterol content was determined using gas liquid chromatography. Of the fatty acids identified, saturated-, monounsaturated-, and polyunsaturated fatty acids represented 44.92, 46.04, and 3.04%, respectively. The Gluteus medius contained the highest percentage of polyunsaturated fats regardless of Quality Grade. Of the fatty acids detected, oleic, palmitic, and stearic acids represented 74.56% of the fatty acid profile of all BAM cuts. Trans fats totaled 6.4% of the fatty acids identified for all the BAM cuts.This study identified seven cuts from three Quality Grades that qualify for USDA Lean and one cut from two Quality Grades that qualify for USDA Extra Lean.iv ACKNOWLEDGMENTS

Beef Loin, Strip Loins (IMPS #180; n = 20) with marbling scores between Modest00 and Modest30 at the 12th and 13th rib interface of the M. longissimus thoracis et lumborum (LL) were collected. Each strip loin was fabricated into 6 samples taken perpendicular to the long axis of the LL from the 13th thoracic vertebra to the fifth lumbar vertebra with the cut made on the anterior side of the respective vertebra. A Computer Vision System Cold Camera measured the LL cross-section of each sample location for USDA marbling score, marbling distribution, average marbling fleck size, LL area, LL length (distance medial to lateral), and LL width (distance dorsal to ventral). In the present study, mean LL marbling score decreased (P < 0.05) from the second lumbar vertebrae location to the fifth lumbar vertebrae location. Marbling size and marbling distance were the smallest (P < 0.05) in samples from the 13th thoracic vertebrae location. The LL area and width was largest (P < 0.05) for the samples from the most anterior location and thus decreased (P < 0.05) as the samples became more posterior. Samples from the most posterior end of the strip loin were the longest (P < 0.05) in length. It was observed that marbling score, distribution, and size, as well as, LL area, length, and width vary from anterior to posterior in the strip loin which can have potential marketing implications for food service distributors and retailers.