D. R. Woerner

NATIONAL BEEF QUALITY AUDIT-2011: IN-PLANT SURVEY OF TARGETED CARCASS CHARACTERISTICS RELATED TO QUALITY, QUANTITY, VALUE, AND MARKETING OF FED STEERS AND HEIFERS

The 2011 National Beef Quality Audit (NBQA-2011) assessed the current status of quality and consistency of fed steers and heifers. Beef carcasses (n = 9,802), representing approximately 10% of each production lot in 28 beef processing facilities, were selected randomly for the survey. Carcass evaluation for the cooler assessment of this study revealed the following traits and frequencies: sex classes of steer (63.5%), heifer (36.4%), cow (0.1%), and bullock (0.03%); dark cutters (3.2%); blood splash (0.3%); yellow fat (0.1%); calloused rib eye (0.05%); overall maturities of A (92.8%), B (6.0%), and C or greater (1.2%); estimated breed types of native (88.3%), dairy type (9.9%), and Bos indicus (1.8%); and country of origin of United States (97.7%), Mexico (1.8%), and Canada (0.5%). Certified or marketing program frequencies were age and source verified (10.7%), ≤A(40) (10.0%), Certified Angus Beef (9.3%), Top Choice (4.1%), natural (0.6%), and Non-Hormone-Treated Cattle (0.5%); no organic programs were observed. Mean USDA yield grade (YG) traits were USDA YG (2.9), HCW (374.0 kg), adjusted fat thickness (1.3 cm), LM area (88.8 cm2), and KPH (2.3%). Frequencies of USDA YG distributions were YG 1, 12.4%; YG 2, 41.0%; YG 3, 36.3%; YG 4, 8.6%; and YG 5, 1.6%. Mean USDA quality grade (QG) traits were USDA quality grade (Select(93)), marbling score (Small(40)), overall maturity (A(59)), lean maturity (A(54)), and skeletal maturity (A(62)). Frequencies of USDA QG distributions were Prime, 2.1%; Choice, 58.9%; Select, 32.6%; and Standard or less, 6.3%. Marbling score distribution was Slightly Abundant or greater, 2.3%; Moderate, 5.0%; Modest, 17.3%; Small, 39.7%; Slight, 34.6%; and Traces or less, 1.1%. Carcasses with QG of Select or greater and YG 3 or less represented 85.1% of the sample. This is the fifth benchmark study measuring targeted carcass characteristics, and information from this survey will continue to help drive progress in the beef industry. Results will be used in extension and educational programs as teaching tools to inform beef producers and industry professionals of the current state of the U.S. beef industry.

Effectiveness of USDA instrument-based marbling measurements for categorizing beef carcasses according to differences in longissimus muscle sensory attributes1

This study quantified relationships between USDA instrument marbling measurements and LM sensory attributes (tenderness, flavor, juiciness), and shear force. Heifer (n = 390) and steer (n = 328) carcasses (all A-maturity) were selected at 4 beef processing plants in Colorado, Kansas, Nebraska, and Texas to represent 7 marbling degrees: traces (TR), slight (SL), small (SM), modest (MT), moderate (MD), slightly abundant (SA), and moderately abundant (MA). Classification into marbling groups was based on marbling scores determined using USDA-approved VBG 2000 grading systems. Strip loin steaks were obtained from both sides of each carcass and aged for 14 d. One steak was used to obtain Warner-Bratzler shear force (WBSF) and slice shear force (SSF) measurements. The other steak was evaluated by a trained sensory panel for juiciness, tenderness, intensity of flavors characterized as meaty/brothy, buttery/beef fat, bloody/serumy, livery/organy, and grassy; and overall sensory experience (negative or positive). Instrument marbling score explained 45%, 40%, 32%, 71%, and 61% of the observed variation in panel ratings for juiciness, tenderness, meaty/brothy flavor intensity, buttery/beef fat flavor intensity, and overall sensory experience, respectively. Increased degree of marbling resulted in steaks having greater (P < 0.001) juiciness (MA > SA > MD > MT > SM > SL = TR), meaty/brothy flavor (MA = SA > MD = MT > SM > SL > TR), and buttery/beef fat flavor (MA > SA > MD > MT > SM > SL > TR). Steak tenderness also increased (P < 0.001) as marbling degree increased; however, tenderness differences among marbling degrees differed for steers (MA = SA > MD = MT > SM > SL = TR) and heifers (MA = SA > MD > MT > SM > SL > TR). Steaks produced by steers had lower (P < 0.05) WBSF and SSF values, and were rated as more tender by sensory panelists than steaks produced by heifers, but the effect of sex on panel tenderness was significant only among steaks with TR marbling. Results of this study showed that instrument-based classification of beef carcasses, according to differences in marbling, effectively identified subsequent differences in strip loin steak sensory performance. Nearly all (98 to 99%) steaks with MA or SA marbling, and most (between 80% and 90%) steaks with MD and MT marbling, received positive ratings for overall sensory experience. In comparison, 62% of SM steaks, 29% of SL steaks, and 15% of TR steaks received positive sensory experience ratings.

Determining the prevalence of Escherichia coli O157 in cattle and beef from the feedlot to the cooler.

Prevalence of Escherichia coli O157 on cattle entering the slaughter floor may range from 10 to > 70%. This study was conducted to determine the effect of E. coli O157 prevalence in fecal pats collected from feedlot pen floors on subsequent E. coli O157 prevalence on carcasses at various points in the slaughter process. Fecal pats from the feedlot pen floor were collected within 3 days before slaughter. During cattle processing at the slaughter facility, additional samples were collected from the hide, from the colon, and from the carcasses before and after evisceration and after final decontamination. Of 15 lots (a group of cattle from the same pen from a feedlot) sampled, 87% had at least one positive fecal pat from the feedlot floor, 47% had a positive hide sample, 73% had a positive colon/fecal sample, and 47% had a positive carcass sample preevisceration; however, only 8% of lots had a positive carcass sample postevisceration or after final intervention. Of the total samples tested (n = 1,328), 24.7, 14.7, 27.6, 10.1, 1.4, and 0.3% of fecal pats from the feedlot floor, hide, colon, preevisceration, postevisceration, and final intervention samples, respectively, were positive for E. coli O157. Pens with greater than 20% positive fecal pats from the feedlot floor had 25.5% hide, 51.4% colon, and 14.3, 2.9, and 0.7% carcass samples positive at preevisceration, at postevisceration, and after final intervention, respectively. However, fecal pats from feedlot floor samples that contained less than 20% positive fecal samples showed lower pathogen prevalence, with 5.0% hide, 7.5% colon, and 6.3, 0, and 0% carcass positive samples at preevisceration, postevisceration, and post-final intervention, respectively. Data from this study can be used as part of risk assessment processes in order to identify mitigation strategies to minimize prevalence of E. coli O157 on fresh beef carcasses.

Use of Metagenomic Shotgun Sequencing Technology To Detect Foodborne Pathogens within the Microbiome of the Beef Production Chain

ABSTRACT Foodborne illnesses associated with pathogenic bacteria are a global public health and economic challenge. The diversity of microorganisms (pathogenic and nonpathogenic) that exists within the food and meat industries complicates efforts to understand pathogen ecology. Further, little is known about the interaction of pathogens within the microbiome throughout the meat production chain. Here, a metagenomic approach and shotgun sequencing technology were used as tools to detect pathogenic bacteria in environmental samples collected from the same groups of cattle at different longitudinal processing steps of the beef production chain: cattle entry to feedlot, exit from feedlot, cattle transport trucks, abattoir holding pens, and the end of the fabrication system. The log read counts classified as pathogens per million reads for Salmonella enterica, Listeria monocytogenes, Escherichia coli, Staphylococcus aureus, Clostridium spp. (C. botulinum and C. perfringens), and Campylobacter spp. (C. jejuni, C. coli, and C. fetus) decreased over subsequential processing steps. Furthermore, the normalized read counts for S. enterica, E. coli, and C. botulinum were greater in the final product than at the feedlots, indicating that the proportion of these bacteria increased (the effect on absolute numbers was unknown) within the remaining microbiome. From an ecological perspective, data indicated that shotgun metagenomics can be used to evaluate not only the microbiome but also shifts in pathogen populations during beef production. Nonetheless, there were several challenges in this analysis approach, one of the main ones being the identification of the specific pathogen from which the sequence reads originated, which makes this approach impractical for use in pathogen identification for regulatory and confirmation purposes.

Activity of Caprylic Acid, Carvacrol, ɛ‐Polylysine and their Combinations against Salmonella in Not‐Ready‐to‐Eat Surface‐Browned, Frozen, Breaded Chicken Products

UNLABELLED Caprylic acid (CAA), carvacrol (CAR), ε-polylysine (POL), and their combinations were evaluated for reduction of Salmonella contamination in not-ready-to-eat surface-browned, frozen, breaded chicken products. Fresh chicken breast meat pieces (5 × 5 × 5 cm) were inoculated with Salmonella (7-strain mixture; 4-5 log CFU/g) and mixed with distilled water (control) or with CAA, CAR, and POL as single or combination treatments of 2 or 3 ingredients. Sodium chloride (1.2%) and sodium tripolyphosphate (0.3%) were added to all formulations, followed by grinding of the mixtures and forming into 9 × 5 × 3 cm portions. Sample surfaces were brushed with egg whites, coated with breadcrumbs, surface-browned in an oven (208 °C, 15 min), packaged, and stored at -20 °C (7 d). Total reductions of inoculated Salmonella in untreated (control) surface-browned, breaded products after frozen storage were 0.8 to 1.4 log CFU/g. In comparison, single treatments of CAA (0.25% to 1.0%), CAR (0.3% to 0.5%), and POL (0.125% to 1.0%) reduced counts by 2.9 to at least 4.5, 3.4 to at least 4.4, and 1.4 to 2.3 log CFU/g, respectively, depending on concentration. Pathogen counts of products treated with 2- or 3-ingredient combination treatments (0.03125% to 0.25% CAA, 0.0375% to 0.3% CAR, and/or 0.5% POL) were 0.4 to at least 3.3 log CFU/g lower (depending on treatment) than those of the untreated controls. The antimicrobial activity of 2-ingredient combinations comprised of 0.125% CAA, 0.15% CAR, or 0.5% POL was enhanced (P < 0.05) when applied as a 3-ingredient combination (that is, 0.125% CAA + 0.15% CAR + 0.5% POL). These data may be useful for the selection of antimicrobial treatments to reduce Salmonella contamination in not-ready-to-eat processed chicken products. PRACTICAL APPLICATION Findings from the study may be useful for the selection of suitable antimicrobials, concentrations, and combinations to reduce Salmonella contamination in not-ready-to-eat surface-browned, frozen, breaded chicken products.

National Beef Quality Audit-2011: Harvest-floor assessments of targeted characteristics that affect quality and value of cattle, carcasses, and byproducts.

The National Beef Quality Audit-2011 (NBQA-2011) was conducted to assess targeted characteristics on the harvest floor that affect the quality and value of cattle, carcasses, and byproducts. Survey teams evaluated approximately 18,000 cattle/carcasses between May and November 2011 in 8 beef processing facilities. Cattle identification methods were lot visual tags (85.7%), individual visual tags (50.6%), electronic tags (20.1%), metal-clip tags (15.7%), other (5.3%), none (2.5%), and wattles (0.5%). Hide colors or breed types were black (61.1%), red (12.8%), yellow (8.7%), Holstein (5.5%), brown (5.0%), gray (5.0%), white (1.4%), and brindle (1.0%). Brand frequencies were none (55.2%), 1 (40.4%), 2 (4.4%), and 3 or more (0.04%) brands, and brands were located on the butt (35.2%), side (9.0%), and shoulder (2.5%). Hide locations of mud or manure were no mud/manure (49.2%), legs (36.8%), belly (23.7%), side (14.9%), top-line (11.0%), and tail region (13.7%). There were 76.2% of cattle without horns, and the majority of those with horns (71.6%) were between 0 cm and 12.7 cm in length. Permanent incisor numbers were zero (87.3%), 1 (1.4%), 2 (8.0%), 3 (0.9%), 4 (1.9%), 5 (0.3%), 6 (0.2%), 7 (0.1%), and 8 (0.02%). Most carcasses (77.0%) were not bruised, 18.7% had 1 bruise, 3.4% had 2 bruises, 0.6% had 3 bruises, and 0.3% had more than 3 bruises. Bruise locations were loin (50.1%), rib (21.3%), chuck (13.8%), round (7.3%), and brisket/flank/plate (7.5%). Condemnation item and incidence were whole carcass (none recorded), liver (20.9%), lungs (17.3%), tongue (10.0%), viscera (9.3%), and head (7.2%). Compared with the NBQA-2005, the NBQA-2011 had an increased percentage of black-hided cattle (56.3 vs. 61.1%), more cattle with brands (38.7 vs. 44.8%), and more cattle with some form of identification (93.3 vs. 97.5%). In addition, there was a lesser percentage of carcasses with bruising in 2011 (23.0%) than in 2005 (35.2%), as well as a smaller percentage of carcasses with more than 1 bruise (2005 = 9.4% vs. 2011 = 4.2%). Compared with the 2005 audit, a similar percentage of the cattle were deemed 30 mo of age or older using dentition (2005 = 2.7% vs. 2011 = 3.3%). The information from NBQA-2011 helps the beef industry measure progress against previous NBQA assessments and provides a benchmark for future educational and research activities.

Characterization of the resistome in manure, soil and wastewater from dairy and beef production systems.

It has been proposed that livestock production effluents such as wastewater, airborne dust and manure increase the density of antimicrobial resistant bacteria and genes in the environment. The public health risk posed by this proposed outcome has been difficult to quantify using traditional microbiological approaches. We utilized shotgun metagenomics to provide a first description of the resistome of North American dairy and beef production effluents, and identify factors that significantly impact this resistome. We identified 34 mechanisms of antimicrobial drug resistance within 34 soil, manure and wastewater samples from feedlot, ranch and dairy operations. The majority of resistance-associated sequences found in all samples belonged to tetracycline resistance mechanisms. We found that the ranch samples contained significantly fewer resistance mechanisms than dairy and feedlot samples, and that the resistome of dairy operations differed significantly from that of feedlots. The resistome in soil, manure and wastewater differed, suggesting that management of these effluents should be tailored appropriately. By providing a baseline of the cattle production waste resistome, this study represents a solid foundation for future efforts to characterize and quantify the public health risk posed by livestock effluents.

Effects of dietary ractopamine hydrochloride and zilpaterol hydrochloride supplementation on performance, carcass traits, and carcass cutability in beef steers

British × Continental steers (initial BW = 484.6 kg) were fed at a commercial feed yard to evaluate the effects of β-agonists on live performance, carcass characteristics, and carcass subprimal yield. Weights and ultrasonic measurements were used to allocate steers to pens (n = 40) divided equally into 4 blocks, with 2 treatment replicates per block. Pens were randomly assigned to 1 of 5 treatments: control; ractopamine-HCl (RH) fed at 200 or 300 mg • steer(-1) • d(-1), or 400 mg • steer(-1) • d(-1) top dress for the final 30 d of feeding; or zilpaterol-HCl (ZH) fed at 7.5 mg/kg beginning 23 d before slaughter with a 3-d withdrawal period. Steers were harvested by block at a commercial facility over 4 wk. Carcass based performance measures were calculated using initial pen weights and actual DMI. From each pen, eight carcasses that were within ± 13.6 kg of the mean pen HCW were selected such that two carcasses were within each of the following four Yield Grade (YG) ranges: YG ≤ 2.8; 2.9-3.2; 3.3-3.5; YG > 3.5. Carcasses were fabricated by plant personnel to determine subprimal yield. Steers fed ZH had higher carcass-based ADG and carcass-based G:F compared with all other treatments (P < 0.05). Carcass-based ADG and carcass-based G:F were higher in RH treatments compared with controls (P < 0.05). Steers fed ZH had higher dressing percentages (1.0 to 1.6%) and larger LM area (4.3 to 6.7 cm(2)) than all other treatments (P < 0.05). Use of RH 400 and ZH increased HCW 6.3 and 11.1 kg, respectively compared with controls (P < 0.05). Compared with controls, RH 300 and ZH decreased marbling score and the frequency of carcasses qualifying for upper 2/3 Choice premiums (P < 0.05). Beta-agonists increased subprimal yield from the round and loin; however, blade meat was the only cut from the rib or chuck affected by β-agonists. Results from this study indicated improvements in performance and carcass traits as a result of β-agonist use; however, differences between ZH, RH 400, and RH 300 treatments were minimal for carcass traits and cutability. Increases in saleable yield following β-agonist use were not uniformly distributed across the four major primals and the majority of weight gain occurred in the lower priced cuts of the round and chuck. Increased response of the lower priced cuts to β-agonists could have economic implications to packers.

Identifying consumer preferences for specific beef flavor characteristics in relation to cattle production and postmortem processing parameters

Sensory analysis of ground LL samples representing 12 beef product categories was conducted in 3 different regions of the U.S. to identify flavor preferences of beef consumers. Treatments characterized production-related flavor differences associated with USDA grade, cattle type, finishing diet, growth enhancement, and postmortem aging method. Consumers (N=307) rated cooked samples for 12 flavors and overall flavor desirability. Samples were analyzed to determine fatty acid content. Volatile compounds produced by cooking were extracted and quantified. Overall, consumers preferred beef that rated high for beefy/brothy, buttery/beef fat, and sweet flavors and disliked beef with fishy, livery, gamey, and sour flavors. Flavor attributes of samples higher in intramuscular fat with greater amounts of monounsaturated fatty acids and lesser proportions of saturated, odd-chain, omega-3, and trans fatty acids were preferred by consumers. Of the volatiles identified, diacetyl and acetoin were most closely correlated with desirable ratings for overall flavor and dimethyl sulfide was associated with an undesirable sour flavor.

Comparison of decontamination efficacy of antimicrobial treatments for beef trimmings against Escherichia coli O157:H7 and 6 non-O157 Shiga toxin-producing E. coli serogroups.

UNLABELLED The decontamination efficacy of 6 chemical treatments for beef trimmings were evaluated against Escherichia coli O157:H7 and 6 non-O157 Shiga toxin-producing E. coli (nSTEC) serogroups. Rifampicin-resistant 4-strain mixtures of E. coli O157:H7 and nSTEC serogroups O26, O45, O103, O111, O121, and O145 were separately inoculated (3 to 4 log CFU/cm(2)) onto trimmings (10 × 5 × 1 cm; approximately 100 g) fabricated from beef chuck rolls, and were immersed for 30 s in solutions of acidified sodium chlorite (0.1%, pH 2.5), peroxyacetic acid (0.02%, pH 3.8), sodium metasilicate (4%, pH 12.5), Bromitize(®) Plus (0.0225% active bromine, pH 6.6), or AFTEC 3000 (pH 1.2), or for 5 s in SYNTRx 3300 (pH 1.0). Each antimicrobial was tested independently together with an untreated control. Results showed that all tested decontamination treatments were similarly effective against the 6 nSTEC serogroups as they were against E. coli O157:H7. Irrespective of pathogen inoculum, treatment of beef trimmings with acidified sodium chlorite, peroxyacetic acid, or sodium metasilicate effectively (P < 0.05) reduced initial pathogen counts (3.4 to 3.9 log CFU/cm(2)) by 0.7 to 1.0, 0.6 to 1.0, and 1.3 to 1.5 log CFU/cm(2), respectively. Reductions of pathogen counts (3.1 to 3.2 log CFU/cm(2)) by Bromitize Plus, AFTEC 3000, and SYNTRx 3300 were 0.1 to 0.4 log CFU/cm(2), depending on treatment. Findings of this study should be useful to regulatory authorities and the meat industry as they consider nSTEC contamination in beef trimmings. PRACTICAL APPLICATIONS Findings of this study should be useful to: (i) meat processors as they design and conduct studies to validate the efficacy of antimicrobial treatments to control pathogen contamination on fresh beef products; and (ii) regulatory agencies as they consider approaches for better control of the studied pathogens.