Argenis Rodas-González

Salmonella and Escherichia coli O157:H7 prevalence in cattle and on carcasses in a vertically integrated feedlot and harvest plant in Mexico.

To determine the prevalence of Salmonella and Escherichia coli O157:H7 in cattle feedlots and the impact of subsequent contamination on carcasses in a Mexican Federal Inspection Type Standards harvest facility, 250 animals were tagged and sampled in each step of the slaughter process. Samples were taken from hides and fecal grabs, and composite samples were taken from three anatomical carcass sites (hindshank, foreshank, and inside round) during the slaughter process, at preevisceration (PE), prior to entering the hot box (PHB), and after 24 h of dry chilling (DC). Additionally, 250 fecal samples were collected from the feedlot (FL), holding pens (HP), and intestinal feces (IF), and water samples were taken from the HP area. E. coli O157:H7 and Salmonella detection were carried out with the BAX System, immunomagnetic separation, and conventional methods. Overall Salmonella prevalence was 52.5%. The highest prevalence (92.4%) was found on hides, followed by feces from the HP (91.0%), FL (55.56%), PE (49.0%), IF (46.8%), and PHB (24.8%), for all sampling periods combined. The lowest prevalence of 6.0% was found after DC. The overall prevalence of E. coli O157:H7 was as follows: 11.7% for hides, 5.2% for IF, 2.7% for FL, 2.0% for HP, 0.8% for PE, 0.4% for PHB, and 0.4% for the cooler. High prevalence of Salmonella in IF and on hides present a significant risk factor for contamination by Salmonella at the different processing steps. These results serve as a warning as to the risks of contamination in meats for these pathogens and the importance of following good manufacturing practices during beef production processes.

Review: Canadian beef grading - Opportunities to identify carcass and meat quality traits valued by consumers

Aalhus, J. L., López-Campos, Ó., Prieto, N., Rodas-González, A., Dugan, M. E. R., Uttaro, B. and Juárez, M. 2014. Review: Canadian beef grading - Opportunities to identify carcass and meat quality traits valued by consumers. Can. J. Anim. Sci. 94: 545-556. Beef value is in the eye, mouth or mind of the consumer; however, currently, producers are paid on the basis of carcass grade. In general, affluent consumers are becoming more discerning and are willing to pay for both credence and measureable quality differences. The Canadian grading system for youthful carcasses identifies both lean yield and quality attributes, whereas mature carcasses are broadly categorized. Opportunities exist to improve the prediction of lean meat yield and better identify meat quality characteristics in youthful beef, and to obtain additional value from mature carcasses through muscle profiling. Individual carcass identification along with development of database systems like the Beef InfoXchange System (BIXS) will allow a paradigm shift for the industry as traits of economic value can be easily identified to improve marketing value chains. In the near future, developing technologies (e.g., grade cameras, dual energy X-ray absorptiometry, and spectroscopic methods such as near infrared spectroscopy, Raman spectroscopy and hyperspectral imaging) will be successfully implemented on-line to identify a multitude of carcass and quality traits of growing importance to segments of the consuming population.

Cholesterol and fatty acid composition of longissimus thoracis from water buffalo (Bubalus bubalis) and Brahman-influenced cattle raised under savannah conditions

Male (n=66) water buffalo (Buffalo) and Brahman-influenced cattle (Brahman) were born, raised, weaned, fattened on grazing savannah and harvested at two different ages (19 and 24months) to compare lipid composition of the longissimus thoracis muscle. Half of the animals were castrated at seven months of age (MOA) to examine the castration effects. At 24 MOA Brahman steers showed the highest content of total lipids (P<0.05). No significant variation was detected in cholesterol content for either the main or interaction effects in the age groups. Some individual fatty acids varied with the species (P<0.05), however, interspecific similarities were found in fatty acid ratios. For health-related indices, only atherogenic index (AI) showed lower values in favor of Buffalo meat (P<0.05) at both harvesting ages. Although, meat derived from both bovid groups was leaner and showed lower cholesterol level, AI indicates that Buffalo meat might be beneficial from a human health standpoint.

Virulence characterization and molecular subtyping of typical and atypical Escherichia coli O157:H7 and O157:H(-) isolated from fecal samples and beef carcasses in Mexico.

The objective of the study was to characterize virulence genes and subtype Escherichia coli O157:H7 and O157:H( 2 ) isolates obtained from a vertically integrated feedlot slaughter plant in Mexico. A total of 1,695 samples were collected from feedlots, holding pens, colon contents, hides, and carcasses. E. coli O157:H7 detection and confirmation was carried out using conventional microbiology techniques, immunomagnetic separation, latex agglutination, and the BAX system. A total of 97 E. coli O157 strains were recovered and screened for key virulence and metabolic genes using multiplex and conventional PCR. Eighty-eight (91.72%) of the strains carried stx2, eae, and ehxA genes. Ten isolates (8.25%) were atypical sorbitol-fermenting strains, and nine were negative for the flicH7 gene and lacked eae, stx1, stx2, and ehxA. One sorbitol-positive strain carried stx2, eae, tir, toxB, and iha genes but was negative for stx1 and ehxA. Pulsed-field gel electrophoresis (PFGE) analysis yielded 49 different PFGE subtypes, showing a high genetic diversity; however, the majority of the typical isolates were closely related (80 to 90% cutoff). Atypical O157 isolates were not closely related within them or to typical E. coli O157:H7 isolates. Identical PFGE subtypes were found in samples obtained from colon contents, feedlots, holding pens, and carcasses. Isolation of a sorbitolfermenting E. coli O157 positive for a number of virulence genes is a novel finding in Mexico. These data showed that genetically similar strains of E. coli O157:H7 can be found at various stages of beef production and highlights the importance of preventing cross-contamination at the pre- and postharvest stages of processing.

Survival and Reduction of Shiga Toxin‐Producing Escherichia coli in a Fresh Cold‐Pressed Juice Treated with Antimicrobial Plant Extracts

This study was conducted to evaluate the survival of 7 Shiga-toxigenic Escherichia coli (STEC) in fresh cold-pressed juice and the antimicrobial efficacy of 4 essential oils (EO: achillea, rosemary, sage, and thyme). The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of each EO was determined using microdilution assays evaluated at pH levels 4 and 7; as well as at 4 and 25 °C; daily for up to 5 d. Results indicated that 5 of 7 serotypes survived well in cold-pressed raw juice for at least 4 d at 4 °C and pH 3.5 with no significant (P > 0.05) reduction in viability. The EO showed varying degrees of antimicrobial activity against the 7 STEC. The MIC and MBCs were lowest for thyme (2 μg/L) and highest for sage (15 to 25 μg/L). The antimicrobial activity was enhanced at low pH and temperature. Data showed that although the top 7 STEC could survive low pH and temperature in vitro and in cold-pressed juices, EO, especially from thyme and rosemary, reduced STEC to an undetectable level at 4 °C, suggesting that they could be used as natural antimicrobials in juice.

Effects of electrical stimulation on meat quality of bison striploin steaks and ground patties

Abstract: As bison is characteristically dark in colour, this study was conducted to determine if high-voltage electrical stimulation (HVES) could improve the colour and other quality characteristics in bison, similar to positive effects of HVES previously observed in beef. Forty bison bull carcasses were split and HVES (400 V peak, 5 ms pulses at 15 pulses s-1 for 30 s) was applied to the right sides and subsequently evaluated for grade characteristics, metabolic activity, and quality characteristics. The bison carcasses used in this study had a wide range of lean and fat, with minimal marbling. In the present study, HVES had no effect on bison quality traits, sensory attributes, retail display characteristics, nor the glycolytic metabolites (P > 0.05) except lactate. Inherent differences in muscle fibre type or physical carcass differences may have influenced the response to the electrical parameters used in the present study and merits further investigation.

Corn supplementation as a winter-feeding strategy alters maternal feeding behavior and endocrine profiles in mid- to late-gestating beef cows1

© The Author(s) 2018. Published by Oxford University Press on behalf of the American Society of Animal Science. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact journals.permissions@oup.com Transl. Anim. Sci. 2018.2:S106–S111 doi: 10.1093/tas/txy059

Predictability of lean product, bone, and fat trim in beef carcasses from Costa Rica

Data from 292 hot fat trimmed carcasses derived from Costa Rican cattle were used to predict yield of fabricated boneless, closely-trimmed, high-valued cuts (BVS, by weight and percentage); yield of total saleable product (TSP, by weight and percentage); and percentage yields of bone and trim fat. Backfat thickness was not significantly associated with weight of BVS or TSP. Carcass weight explained 93.7% and 95.9% of the total variation in weight of BVS and TSP, respectively. Equations for predicting percentage yields of BVS and TSP showed little predictive efficacy. Conversely, the greater precision of the equations selected to predict the quantity (kg) of BVS or TSP, offers a practical alternative of using them in hot fat trimmed carcasses.

Exploring innovative possibilities of recovering the value of dark-cutting beef in the Canadian grading system

Abstract This study examined if different color intensities of dark-cutting beef carcasses (Dark B4/Moderate B4) were similar in quality to normal (N) carcasses of a lower marbling score. The eating quality from abnormal (AB) dark-cutting carcasses (normal pH) was also evaluated to determine if AB should receive the same penalty as classic (CL) dark-cutting carcasses in the Canadian grading system. B4-grade carcasses, regardless of dark color intensity, exhibited increased toughness and greater off-flavor than N carcasses of a lower marbling score. Additionally, AB and borderline (BD) carcasses were tougher than N. The CL dark cutters, albeit similar in tenderness to N carcasses, had greater off-flavor and less beef flavor intensity. Downgrading B4 carcasses one quality grade based on the marbling score, with no further carcass demerits, is likely not sufficient, and further devaluations of dark cutters may be warranted. As well, AB and BD carcasses were of lower quality compared to N carcasses and, therefore, deserve some economic penalty.

Muscle profiling of retail characteristics within the Canadian cull cow grades

Abstract: Composition, drip loss, objective colour, and measures of colour stability during 3 d of retail display were benchmarked for 11 muscles obtained from youthful beef and cow carcasses (n = 120). Traits were compared between the muscles from cow carcasses, graded using the Canadian grading system (D1, D2, D3, and D4; >50% ossification), and muscles from A/AA youthful carcasses [identified as under 30 mo (UTM) of age based on dentition and <50% ossification or over 30 mo (OTM) of age based on dentition, but <50% ossification]. Muscles from D3-graded carcasses had a lower intramuscular fat content, aside from these carcasses, all other cow carcass grades had muscles with either equivalent or higher fat content. Most muscles from cow carcasses had consistently darker meat (lower L*; P < 0.05), yet the colour stability measures were similar between most muscles from cow-graded carcasses and UTM over 3 d of retail display. Notably, the infraspinatus (flat iron) from cow carcasses did not differ in colour from UTM beef. In general, OTM carcasses had similar colour and composition attributes to the UTM beef. Given the retail performance of muscles from cow carcasses, opportunities may exist to better utilize specific muscles from these carcasses.