Browsing by Author "Brashears, Mindy M. (TTU)"
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Item A systematic approach to identify and characterize the effectiveness and safety of novel probiotic strains to control foodborne pathogens(2019) Ayala, Diana I. (TTU); Cook, Peter W. (TTU); Franco, Jorge G. (TTU); Bugarel, Marie (TTU); Kottapalli, Kameswara R. (TTU); Loneragan, Guy H. (TTU); Brashears, Mindy M. (TTU); Nightingale, Kendra K. (TTU)A total of 44 lactic acid bacteria (LAB) strains originally isolated from cattle feces and different food sources were screened for their potential probiotic features. The antimicrobial activity of all isolates was tested by well-diffusion assay and competitive exclusion on broth against Salmonella Montevideo, Escherichia coli O157:H7 and Listeria monocytogenes strain N1-002. Thirty-eight LAB strains showed antagonistic effect against at least one of the pathogens tested in this study. Improved inhibitory effect was observed against L. monocytogenes with zones of inhibition up to 24 mm when LAB overnight cultures were used, and up to 21 mm when cell-free filtrates were used. For E. coli O157:H7 and Salmonella maximum inhibitions of 12 and 11.5 mm were observed, respectively. On broth, 43 strains reduced L. monocytogenes up to 9.06 log10 CFU/ml, 41 reduced E. coli O157:H7 up to 0.84 log10 CFU/ml, and 32 reduced Salmonella up to 0.94 log10 CFU/ml 24 h after co-inoculation. Twenty-eight LAB isolates that exhibited the highest inhibitory effect among pathogens were further analyzed to determine their antimicrobial resistance profile, adhesion potential, and cytotoxicity to Caco-2 cells. All LAB strains tested were susceptible to ampicillin, linezolid, and penicillin. Twenty-six were able to adhere to Caco-2 cells, five were classified as highly adhesive with > 40 bacterial cells/Caco-2 cells. Low cytotoxicity percentages were observed for the candidate LAB strains with values ranging from -5 to 8%. Genotypic identification by whole genome sequencing confirmed all as members of the LAB group; Enterococcus was the genus most frequently isolated with 21 isolates, followed by Pediococcus with 4, and Lactobacillus with 3. In this study, a systematic approach was used for the improved identification of novel LAB strains able to exert antagonistic effect against important foodborne pathogens. Our findings suggest that the selected panel of LAB probiotic strains can be used as biocontrol cultures to inhibit and/or reduce the growth of L. monocytogenes, Salmonella, and E. coli O157:H7 in different matrices, and environments.Item Bio-Mapping of Microbial Indicators to Establish Statistical Process Control Parameters in a Commercial Beef Processing Facility(2022) Vargas, David A. (TTU); Rodríguez, Karla M. (TTU); Betancourt-Barszcz, Gabriela K. (TTU); Ajcet-Reyes, Manoella I. (TTU); Dogan, Onay B. (TTU); Randazzo, Emile; Sánchez-Plata, Marcos X. (TTU); Brashears, Mindy M. (TTU); Miller, Markus F. (TTU)The objective was to conduct a bio-mapping of microbial indicators to determine statistical process control (SPC) parameters at a beef processing plant to establish microbiological baselines and process control parameters to support food safety management decisions. EZ-Reach™ swabs were used to collect 100 cm2 area samples at seven different locations throughout the beef processing line at four different regions on the carcass. Each of the eight sampling days evaluated included three samples collected per sampling location/carcass region for a total of 84 samples per day. Enumeration of total aerobic bacteria, Enterobacteriaceae, and Escherichia coli was performed on each sample. Microbial SPC parameters were estimated for each sampling point. Statistical differences between sampling points for all carcass locations (p < 0.001) followed an overall trend with higher values at pre-and post-evisceration with a continuous decrease until final interventions with a slight increase in counts during the chilling process and a final increase after fabrication. Variability at sampling points is the result of the nature of the process and highlights open opportunities for improvement of the food safety system. Microbial baselines and SPC parameters will help support decision making for continuous process improvement, validation of intervention schemes, and corrective action implementation for food safety management.Item Biomapping of microbial indicators on beef subprimals subjected to spray or dry chilling over prolonged refrigerated storage(2021) Casas, Diego E. (TTU); Manishimwe, Rosine (TTU); Forgey, Savannah J. (TTU); Hanlon, Keelyn E. (TTU); Miller, Markus F. (TTU); Brashears, Mindy M. (TTU); Sanchez-Plata, Marcos X. (TTU)As the global meat market moves to never frozen alternatives, meat processors seek opportunities for increasing the shelf life of fresh meats by combinations of proper cold chain management, barrier technologies, and antimicrobial interventions. The objective of this study was to determine the impact of spray and dry chilling combined with hot water carcass treatments on the levels of microbial indicator organisms during the long-term refrigerated storage of beef cuts. Samples were taken using EZ-Reach™ sponge samplers with 25 mL buffered peptone water over a 100 cm2 area of the striploin. Sample collection was conducted before the hot carcass wash, after wash, and after the 24 h carcass chilling. Chilled striploins were cut into four sections, individually vacuum packaged, and stored to be sampled at 0, 45, 70, and 135 days (n = 200) of refrigerated storage and distribution. Aerobic plate counts, enterobacteria, Escherichia coli, coliforms, and psychrotroph counts were evaluated for each sample. Not enough evidence (p > 0.05) was found indicating the hot water wash intervention reduced bacterial concentration on the carcass surface. E. coli was below detection limits (<0.25 CFU/cm2) in most of the samples taken. No significant difference (p > 0.05) was found between coliform counts throughout the sampling dates. Feed type did not seem to influence the (p > 0.25) microbial load of the treatments. Even though no immediate effect was seen when comparing spray or dry chilling of the samples at day 0, as the product aged, a significantly lower (p < 0.05) concentration of aerobic and psychrotrophic organisms in dry-chilled samples could be observed when compared to their spray-chilled counterparts. Data collected can be used to select alternative chilling systems to maximize shelf life in vacuum packaged beef kept over prolonged storage periods.Item Comparison of Three Preharvest Sampling Strategies to Monitor Pathogens in Cattle Lairage Areas(2024) Flach, Makenzie G. (TTU); Dogan, Onay B. (TTU); Miller, Mark F. (TTU); Sanchez, Marcos X. (TTU); Brashears, Mindy M. (TTU)The objective of this study was to compare preharvest monitoring strategies by evaluating three different sampling methods in the lairage area to determine pathogen recovery for each sampling method and incoming pathogen prevalence from the cattle to inform in-plant decision making. Samples were gathered over a 5-month period, from February to June 2022, at a harvesting and processing facility located in Eastern Nebraska. Sampling methods included (i) fecal pats, (ii) boot swabs, and (iii) MicroTally swab. A total of 329 samples were collected over the study period (fecal pats: n = 105, boot swabs: n = 104, and MicroTally swabs: n = 120). Specific media combinations, an incubation temperature of 42°C, and incubation timepoints (18–24 h) were utilized for each matrix and the prevalence of Salmonella, Escherichia coli O157:H7, and six non-O157 Shiga-toxin producing E. coli (STEC) was evaluated using the BAX system Real-Time PCR assay. Overall, results from the study concluded that boot swabs were an effective sampling method for pathogen detection in the cattle lairage area. Boot swabs (97.1%) were statistically more likely to detect for Salmonella (p < 0.05) when compared to fecal pats (67.6%) and MicroTally swab (77.5%) methods. For E. coli O157:H7 and STEC – O26, O121, O45, and O103 prevalence, boot swabs were significantly better at detecting for these pathogens (p < 0.05) than MicroTally swabs (OR = 3.16 – 11.95) and a comparable sampling method to fecal pats (OR = 0.93 – 2.01, p > 0.05). Lastly, all three sampling methods detected a very low prevalence for E. coli O111 and O145; therefore, no further analysis was conducted. The boot swab sampling method was strongly favored because they require little training to implement, are inexpensive, and they do not require much sampling labor; therefore, would be a simple and effective sampling method to implement within the industry to evaluate pathogen prevalence preharvest.Item Controlling listeria monocytogenes scott a on surfaces of fully cooked Turkey deli product using organic acid-containing marinades as postlethality dips(2015) Casco, Gerardo; Johnson, Jennifer L. (TTU); Taylor, T. Matthew; Gaytán, Carlos N.; Brashears, Mindy M. (TTU); Alvarado, Christine Z.This study evaluated the efficacy of organic acids applied singly or in combination as postlethality dips to sliced uncured Turkey deli loaves to inhibit the growth of Listeria monocytogenes (Lm) Scott A. Treatments consisted of sodium lactate (SL; 3.6%), potassium lactate (PL; 3.6%), sodium citrate (SC; 0.75%), a combination of SL and sodium diacetate (SDA; 0.25%), and a combination of SL/PL/SDA, alongside appropriate negative and positive controls. Products were inoculated with 104-105 CFU/mL streptomycinresistant (1500 μg/mL) Lm Scott A prior to treatment. Products were then stored at ~4°C and sampled at 0, 7, 14, 21, 28, 42, and 56 d. The SL/SDA combination applied to Turkey slices extended the lag phase through 21 days of refrigerated storage. Numbers of LmScott A rose by 0.7 log10 CFU/g through the 56 d storage period. The application of the SL/PL/SDA treatment to Turkey product surfaces extended the lag phase through 42 d, with pathogen numbers declining after 21 d.Combination organic acid dips prolonged the lag phase for 2 to 6wk on Turkey product surfaces and can be useful as antimicrobial agents for Lm control on postlethality exposed sliced deli products.Item Draft genome sequence of Enterococcus faecium strain J19, isolated from cabbage(2018) Ayala, Diana I. (TTU); Cook, Peter W. (TTU); Campos, David L. (TTU); Franco, Jorge G. (TTU); Brashears, Mindy M. (TTU); den Bakker, Henk (TTU); Nightingale, Kendra K. (TTU)Herein, we report the draft genome sequence of a newly discovered probiotic strain, Enterococcus faecium J19, which was isolated from cabbage. Strain J19 has shown antagonistic effects against the human foodborne pathogen Listeria monocytogenes in coculture and in different food matrices.Item Draft genome sequence of lactobacillus salivarius L28 isolated from ground beef(2017) Ayal, Diana I. (TTU); Cook, Peter W. (TTU); Campos, David L. (TTU); Brashears, Mindy M. (TTU); den Bakker, Henk (TTU); Nightingale, Kendra K. (TTU)In this report, we describe the draft genome sequence of a newly discovered probiotic strain, Lactobacillus salivarius L28. L. salivarius L28 demonstrates antagonistic effects against human foodborne pathogens, including Escherichia coli O157:H7, Salmonella spp., and Listeria monocytogenes, in coculture experiments and food matrices.Item Effects of Sex Class, a Combined Androgen and Estrogen Implant, and Pasture Supplementation on Growth and Carcass Performance and Meat Quality of Zebu-Type Grass-Fed Cattle(2021) Huerta-Leidenz, Nelson (TTU); Jerez-Timaure, Nancy; Sarturi, Jhones Onorino (TTU); Brashears, Mindy M. (TTU); Miller, Markus F. (TTU); Moya, Alexis; Godoy, SusmiraForty-seven Zebu calves were used to determine the effects of class (bull or steer), supplementation (SUPPL, a poultry litter-based supplement or mineral supplementation), and implant (20 mg estradiol combined with 120 mg of trenbolone acetate or no implant) on growth and carcass performance and beef eating quality. The average daily gain (ADG) of implanted cattle significantly increased for steers, but not for bulls. The SUPPL treatment increased ADG by 8.63% from day 0 to end, and shortened in 73.3 d the time to reach 480 kg BW (p < 0.01). Compared to bulls, the steer carcasses exhibited more desirable maturity and finish scores, thicker back fat (p < 0.05), and yielded greater (p < 0.01) percentages of high-value boneless subprimals (HVBLS) (+1.64%) and total cuts (1.35%). The SUPPL bulls dressed 2.63 and 1.63% greater than non-supplemented bulls and SUPPL steers, respectively (p < 0.05). Meat sensory quality was subtly affected (p < 0.05) by sex class or supplementation. The implant did not affect (p > 0.05) shear force or sensory ratings. The supplementation improved key growth performance traits while it adversely affected tenderness-related sensory traits. The implant enhanced the rate of gain of steers only, without improving cut-out yields or inducing adverse effects on palatability traits in both steers and bulls.Item Establishment of a preliminary baseline of Salmonella presence on pork and goat carcasses harvested in the Bahamas to address food and nutritional security interventions(2018) Hanlon, Keelyn E. (TTU); Echeverry, Alejandro (TTU); Miller, Markus F. (TTU); Brashears, Mindy M. (TTU)• Small island developing states, such as the Bahamas, struggle with productive agricultural systems. This ultimately influences the food and nutritional security of the country. • Agricultural production systems need to be established in small island states, such as the Caribbean to improve food and nutritional security. • Baselines of foodborne pathogens, such as Salmonella, are documented in many developed regions throughout the world. There are gaps in these baselines, however, which need to be established to effectively target food safety intervention strategies.Item In-Plant Intervention Validation of a Novel Ozone Generation Technology (Bio-Safe) Compared to Lactic Acid in Variety Meats(2021) Vargas, David A. (TTU); Casas, Diego E. (TTU); Chávez-Velado, Daniela R. (TTU); Jiménez, Reagan L. (TTU); Betancourt-Barszcz, Gabriela K. (TTU); Randazzo, Emile; Lynn, Dan; Echeverry, Alejandro (TTU); Brashears, Mindy M. (TTU); Sánchez-Plata, Marcos X. (TTU); Miller, Markus F. (TTU)The objective of this experiment was to compare the antimicrobial efficacy of an aqueous ozone intervention and a lactic acid solution on natural microbiota of variety meats in a commercial beef processing plant. EZ-Reach™ swabs were used to collect 100 cm2 area samples before and after ozone and lactic acid intervention application for three different offals (head, heart, and liver). Each repetition included 54 samples per variety meat and antimicrobial for a total of 162 samples per repetition. Enumeration of total aerobic bacteria (APC) and Escherichia coli (EC) was performed on each sample. Microbial counts for both microorganisms evaluated were significantly reduced (p < 0.001) after lactic acid immersion (2–5%) and ozone intervention for all variety meats, with the exception of ozone intervention in EC counts of the heart samples. APC after lactic acid intervention was reduced on average by 1.73, 1.66, and 1.50 Log CFU/sample in the head, heart, and liver, respectively, while after ozone intervention, counts were reduced on average by 1.66, 0.52, and 1.20 Log CFU/sample. EC counts after lactic acid intervention were reduced on average by 0.96, 0.79, and 1.00 Log CFU/sample in the head, heart, and liver, respectively, while after ozone intervention, counts were reduced on average by 0.75, 0.62, and 1.25 Log CFU/sample. The aqueous ozone antimicrobial scheme proved to be a promising intervention for the in-plant reduction of indicator levels in variety meats, specifically heads, hearts, and livers.Item In-plant validation of novel on-site ozone generation technology (Bio-safe) compared to lactic acid beef carcasses and trim using natural microbiota and salmonella and e. coli o157:H7 surrogate enumeration(2021) Casas, Diego E. (TTU); Vargas, David A. (TTU); Randazzo, Emile; Lynn, Dan; Echeverry, Alejandro (TTU); Brashears, Mindy M. (TTU); Sanchez-Plata, Marcos X. (TTU); Miller, Markus F. (TTU)The purpose of this study was to evaluate the antimicrobial efficacy of an aqueous ozone (Bio-Safe) treatment and lactic acid solutions on natural microbiota and E. coli O157:H7 and Salmonella surrogates on beef carcasses and trim in a commercial beef processing plant. For every repetition, 40 carcass and 40 trim swabs (500 cm2 ) were collected. Samples were taken using EZ-Reach™ swabs, and plated into aerobic plate count (APC), coliform, and E. coli Petrifilm™ for enumeration. In addition, a five-strain cocktail (MP-26) of E. coli surrogates was inoculated onto trim. For every trim surrogate repetition, 30 trim pieces were sampled after attachment and after ozone intervention. Samples were diluted and counts were determined using the TEMPO® system for E. coli enumeration. Ozone and lactic acid interventions significantly reduced (p < 0.003) bacterial counts in carcasses and trim samples. Moreover, lactic acid further reduced APC and coliforms in trim samples compared to ozone intervention (p < 0.009). In the surrogate trials, ozone significantly reduced (p < 0.001) surrogate concentration. Historical data from the plant revealed a reduction (p < 0.001) of presumptive E. coli O157:H7 in trim after a full year of ozone intervention implementation. The novel technology for ozone generation and application as an antimicrobial can become an alternative option that may also act synergistically with existing interventions, minimizing the risk of pathogens such as Salmonella and E. coli O157:H7.Item Mitigation of Salmonella in Ground Pork Products through Gland Removal in Pork Trimmings(2023) Jiménez, Reagan L. (TTU); Brashears, Mindy M. (TTU); Bueno López, Rossy (TTU); Vargas, David A. (TTU); Sanchez-Plata, Marcos X. (TTU)Bio-mapping studies conducted in pork harvest and fabrication facilities have indicated that Salmonella is prevalent and mitigations are needed to reduce the pathogen in trim and ground products. Salmonella can be isolated from the lymph nodes and can cause contamination in comminuted pork products. The objective of this study was to determine if physically removing topical and internal lymph nodes in pork products prior to grinding would result in the mitigation of Salmonella and a reduction in indicators in the final ground/comminuted products. In total, three treatment groups were assigned in a commercial pork processing facility as follows: (1) untreated control, (2) topical (surface) glands removed before grinding, and (3) topical, jowl, and internal lymph nodes and glands removed before grinding. Indicator microorganisms were determined using the BioMérieux TEMPO® system and the quantification of Salmonella was performed using the BAX® System Real-Time Salmonella SalQuant® methodology. The removal of lymph nodes located on the topical and internal surfaces and in the jowl significantly (p < 0.05) reduced the presence of Salmonella and also reduced the presence of indicator organisms according to this study. Briefly, 2.5-Log CFU/sample of Salmonella was initially observed in the trim samples, and the ground samples contained 3.8-Log CFU/sample of Salmonella. The total numbers were reduced to less than 1-Log CFU/sample in both trim and ground products. This study indicates a need for lymph node mitigation strategies beginning prior to harvest, in order to prevent contamination in further-processed pork products.Item Multiple Interventions for Improving Food Safety Practices in 2 Small Beef Abattoirs of Honduras and Associated Impacts on Risk-Mitigation Management(2020) Casas, Diego (TTU); Calle, Alexandra (TTU); Bueso, Mariely (TTU); Huerta-Leidenz, Nelson (TTU); Miller, Markus F. (TTU); Brashears, Mindy M. (TTU)Mitigation of risk for Shiga toxin-producing Escherichia coli (STEC) and Salmonella contamination was evaluated after a multiple-intervention approach (comprising food safety education and training, implementation of customized food safety practices and programs, and environmental monitoring programs with audits and corrective actions) in 2 small Honduran beef abattoirs. Previously, neither abattoir had food safety programs in place nor were they subjected to strict food safety regulatory surveillance. Abattoirs A and B were sampled on 4 nonconsecutive months each. Swab samples of abattoir A (n = 160, 40 samples per sampling date) and abattoir B (n = 78, 16-22 samples per sampling date) were taken from direct and indirect food contact surfaces, screened by BAX real-time polymerase chain reaction (PCR) assays and confirmed using immunomagnetic separation, selective media, and latex agglutination. In abattoir A, Salmonella presence was negligible, whereas presumptive STECs were present in 10%, 12.5%, 0%, and 5% of the environmental samples respective to each sampling month, indicating a reduction of STEC (P =.06) by the third and fourth sampling months. Conversely, presumptive STEC presence was negligible in abattoir B, whereas Salmonella presence for each sampling month was of 5.6%, 6.3%, 27.3%, and 0.0%, respectively. Upon the increased pathogen presence detected on the third sampling month, additional actions were taken to reinforce the implementation of food safety practices and programs, which resulted in a Salmonella reduction to 0% by the fourth sampling month (P =.013). The satisfactory results strongly suggest that a multiple-intervention approach is crucial to improve food safety in this type of premises.Item Prevalence of Foodborne Pathogens in Pacific Northwest Beef Feedlot Cattle Fed Two Different Direct-Fed Microbials(2023) Flach, Makenzie G. (TTU); Dogan, Onay B. (TTU); Kreikemeier, Wanda M. (TTU); Nightingale, Kendra K. (TTU); Brashears, Mindy M. (TTU)In recent years, there has been an increased interest in beef cattle shedding of foodborne pathogens due to the potential to contaminate surrounding food crops; however, the number of studies published on this topic has declined as the majority of research has emphasized on postharvest mitigation efforts. A field study was conducted to determine the prevalence of pathogens and indicator bacteria in beef cattle fed two different direct-fed microbials (DFMs). Fecal samples from a total of 3,708 crossbred yearling cattle randomly assigned to 16 pens and two treatment groups at a commercial cattle feedlot were taken. During the study period, diets were supplemented with two different DFMs i.) Lactobacillus acidophilus (NP51) and Propionibacterium freudenreichii (NP24) (9 log10CFU/head/day), and ii.) Lactobacillus salivarius (L28) (6 log10CFU/head/day). Fecal samples from pen floors were collected on days 0, 21, 42, 63, 103, and analyzed for the presence of Salmonella and E. coli O157:H7 and concentration of E. coli O157:H7, Enterobacteriaceae, and C. perfringens. Fecal samples collected from cattle fed L28 had significantly lower concentration of C. perfringens (p < 0.05) and had a similar prevalence with no significant differences in E. coli O157:H7 as those fed NP51/NP24 through the study until day 103. On day 103, the prevalence in cattle fed L28 was 40% with a concentration of 0.95 log10MPN/g while those fed NP51/NP24 were 65% with a concentration of 1.2 log10MPN/g. Cattle supplemented with NP51/NP24 achieved a significant log reduction of EB by 2.4 log10CFU/g over the course of the 103-day supplementation period compared to L28. Salmonella prevalence was also measured, but not detected in any samples at significant amounts to draw conclusions. It is evident that E. coli O157:H7 and other foodborne pathogens are still prevalent in cattle operations and that preharvest mitigation strategies should be considered to reduce the risk to beef products.Item Quantitative Bio-Mapping of Salmonella and Indicator Organisms at Different Stages in a Commercial Pork Processing Facility(2022) Bueno López, Rossy (TTU); Vargas, David A. (TTU); Jimenez, Reagan L. (TTU); Casas, Diego E. (TTU); Miller, Markus F. (TTU); Brashears, Mindy M. (TTU); Sanchez-Plata, Marcos X. (TTU)The purpose of this study was to develop a quantitative baseline of indicator organisms and Salmonella by bio-mapping throughout the processing chain from harvest to final product stages within a commercial conventional design pork processing establishment. Swab samples were taken on the harvest floor at different processing steps, gambrel table, after polisher, before final rinse, after the final rinse, post snap chill, and after peroxyacetic acid (PAA) application, while 2-pound product samples were collected for trim and ground samples. The samples were subjected to analysis for indicator microorganism enumeration, Aerobic Count (AC), Enterobacteriaceae (EB), and generic Escherichia coli (EC), with the BioMérieux TEMPO®. Salmonella prevalence and enumeration was evaluated using the BAX® System Real-Time Salmonella and the SalQuant™ methodology. Microbial counts were converted to Log Colony-forming units (CFU) on a per mL, per g or per sample basis, presented as LogCFU/mL, LogCFU/g and LogCFU/sample, prior to statistical analysis. All indicator microorganisms were significantly reduced at the harvest floor (p-value < 0.001), from gambrel table to after PAA cabinet location. The reduction at harvest was 2.27, 2.46 and 2.24 LogCFU/mL for AC, EB and EC, respectively. Trim sample values fluctuated based on cut, with the highest average AC count found at neck trim (2.83 LogCFU/g). Further process samples showed the highest AC count in sausage with a mean of 5.28 LogCFU/g. EB counts in sausage (3.19 LogCFU/g) showed an evident increase, compared to the reduction observed at the end of harvest and throughout trim processing. EC counts showed a similar trend to EB counts with the highest value found in sausage links (1.60 LogCFU/g). Statistical microbial process control (SPC) parameters were also developed for each of the indicator microorganisms, using the overall mean count ((Formula presented.)), the Lower control limit (LCL) and Upper control limit (UCL) at each sampling location. For Salmonella prevalence, a total of 125/650 samples were found positive (19%). From those positive samples, 47 samples (38%) were suitable for enumeration using the BAX® System SalQuant™, the majority detected at the gambrel table location. From those enumerable samples, 60% were estimated to be between 0.97 and 1.97 LogCFU/sample, while the rest (40%) were higher within the 2.00–4.02 LogCFU/sample range. This study provides evidence for the application of indicator and pathogen quantification methodologies for food safety management in commercial pork processing operations.Item Salmonella in peripheral lymph nodes of healthy cattle at Slaughter(2017) Webb, Hattie E. (TTU); Brichta-Harhay, Dayna M.; Brashears, Mindy M. (TTU); Nightingale, Kendra K. (TTU); Arthur, Terrance M.; Bosilevac, Joseph M.; Kalchayanand, Norasak; Schmidt, John W.; Wang, Rong; Granier, Sophie A.; Brown, Tyson R.; Edrington, Thomas S.; Shackelford, Steven D.; Wheeler, Tommy L.; Loneragan, Guy H. (TTU)To more fully characterize the burden of Salmonella enterica in bovine peripheral lymph nodes (PLN), PLN (n = 5,450) were collected from healthy cattle at slaughter in 12 commercial abattoirs that slaughtered feedlot-fattened (FF) cattle exclusively (n = 7), cattle removed (or culled) from breeding herds (n = 3), or both FF and cull cattle (n = 2). Qualitative and quantitative methods were used to estimate prevalence and concentration of Salmonella in PLN. Isolates were subjected to a variety of phenotypic, serological, and molecular assays. Overall, Salmonella prevalence in PLN from FF and cull cattle was 7.1 and 1.8%. However, burden varied by season in that observed prevalence in PLN collected in cooler or warmer seasons was 2.4 and 8.2%, respectively. Prevalence in PLN from cull cattle in the southwest region of the US was 2.1 and 1.1% for cool and warm seasons, respectively; however, prevalence in FF PLN was far greater in that it was 6.5 and 31.1%, respectively. Salmonella was recovered from 289 (5.6%) PLN and 2.9% (n = 160) of all PLN tested had quantifiable concentrations that varied from 1.6 to 4.9 log10 colony forming units/PLN. The most common serotypes isolated from PLN were Montevideo (26.9%), Lille (14.9%), Cerro (13.0%), Anatum (12.8%), and Dublin (6.9%). In all, 376 unique isolates were collected from the 289 Salmonella-positive PLN. Antimicrobial susceptibility testing revealed the majority (80.6%) of these isolates were pansusceptible; however, 10.7% of isolates were found to be resistant to two or more antimicrobial classes. We were able to document an observed increased in prevalence of Salmonella in PLN during the warmer season, particularly in FF cattle from the southwest region of the US. The mechanisms underlying the observed association between season, region, and production source have yet to be elucidated. Nevertheless, these findings increase our understanding of the sources of contamination of beef products and shed light on transmission dynamics that may be useful in targeting these sources.Item Seasonal effect on Salmonella, Shiga toxin-producing E. coli O157:H7 and non-O157 in the beef industry in Colombia, South America(2021) Calle, Alexandra (TTU); Carrascal, Ana Karina; Patiño, Carlos; Carpio, Carlos (TTU); Echeverry, Alejandro (TTU); Brashears, Mindy M. (TTU)This research investigated the variations in the occurrence of Salmonella, STEC O157:H7 and non-O157 in the beef production chain in Colombia affected by seasons, hypothesizing that pathogen prevalence will be highest in the rainy season owing to soil moisture promoting bacteria multiplication and transfer between animals. To test this hypothesis, samples were obtained from five abattoirs, which represent 50% of the beef production in this country. A total of 1017 samples were collected, from which 606 were bovine feces, 206 were hide swabs, and 205 corresponded to carcass post-intervention. From the 1017 samples, 49.9% (n = 507) were collected during dry season, while 50.1% (n = 510) during rainy season. All samples (n = 1017) underwent screening for E. coli O157:H7 and Salmonella, while only a proportion of fecal samples (n = 339) were screened for the big six STEC serogroups and their virulence markers. The effect of season, age of animal and sex of animal were correlated with the prevalence results. A total of 84.7% of fecal samples carried virulence genes associated to STEC (stx or eae), suggesting that testing and control should be increased for the big-six STEC compared to E. coli O157:H7. Pathogen prevalence in feces was found to be 8.3%, 5.0%, and 51.0% for Salmonella, E. coli O157:H7 and STEC non-O157, respectively. Hides had a prevalence of 15.0% and 6.8% of Salmonella and E. coli O157:H7, respectively. Carcasses post-intervention were found to have 4.4% and 2.5% prevalence of Salmonella and E. coli O157:H7, respectively. A seasonal effect was found for fecal samples. E. coli O157 and non-O157 STEC shedding were significantly higher (P ≤ 0.05) during rainy season compared to dry season. In contrast, hides and carcasses were more likely to present lower incidence of pathogens during rainy months compared to dry season; however, it was significant only for Salmonella on carcasses with estimated odds of detection almost six times higher in the dry season relative to the rainy season (OR = 5.90, 95% CI 1.18–29.57).Item The Effects of Castration, Implant Protocol, and Supplementation of Bos indicus-Influenced Beef Cattle under Tropical Savanna Conditions on Growth Performance, Carcass Characteristics, and Meat Quality(2022) Huerta-Leidenz, Nelson (TTU); Jerez-Timaure, Nancy; Rodas-González, Argenis; Sarturi, Jhones Onorino (TTU); Brashears, Mindy M. (TTU); Miller, Markus F. (TTU); Brashears, Michel Todd (TTU)The effects of castration, supplementation, and implant protocol (IP) on growth, carcass characteristics, and meat quality of grass-fed cattle were evaluated. Two experiments followed a two-way ANOVA and a 2 × 2 factorial arrangement. Experiment-I, 99 bulls were evaluated for: (a) supplementation (mineral (MS) or strategic protein-energy supplementation (SS)), and (b) IP (repeated (day-0 and day-90) Zeranol-72 mg implantation (Zeranol–Zeranol) or Trenbolone Acetate-140 mg/Estradiol-20 mg (day-0) followed by Zeranol-72 mg (day-90) (TBA/E2–Zeranol)). Experiment II, 50 animals were evaluated for: (a) IP (like Experiment-I), and (b) male class (steers vs. bulls). In Experiment-I, SS bulls had greater growth rate, carcass yield, and yield of high-valued boneless lean cuts than MS bulls, while decreasing (p < 0.05) time to harvest. Steaks from SS-bulls on TBA/E2– Zeranol IP were more (p = 0.05) tender than SS/Zeranol–Zeranol counterparts. Experiment-II bulls had greater growth than steers, but decreased (p < 0.05) carcass quality aspects. Zeranol–Zeranol increased (p <0.01) meat tenderness of steers. Interactions (p < 0.05) affected cutability (Experiment-II) and meat sensory traits (Experiment-I/II). The SS improved growth, carcass yield, and shortened days until harvest of bulls, while TBA/E2–Zeranol IP positively affected tenderness in bull meat only. Castration improved carcass quality while the implant effects on cutability and tenderness were male-class dependent.Item Validation of a Bacteriophage Hide Application to Reduce STEC in the Lairage Area of Commercial Beef Cattle Operations(2023) Flach, Makenzie G. (TTU); Dogan, Onay B. (TTU); Miller, Mark F. (TTU); Sanchez-Plata, Marcos X. (TTU); Brashears, Mindy M. (TTU)Finalyse, a T4 bacteriophage, is a pre-harvest intervention that utilizes a combination of bacteriophages to reduce incoming Escherichia coli O157:H7 prevalence by destroying the bacteria on the hides of harvest-ready cattle entering commercial abattoirs. The objective of this study was to evaluate the efficacy of Finalyse, as a pre-harvest intervention, on the reduction in pathogens, specifically E. coli O157:H7, on the cattle hides and lairage environment to overall reduce incoming pathogen loads. Over 5 sampling events, a total of 300 composite hide samples were taken using 25 mL pre-hydrated Buffered Peptone Water (BPW) swabs, collected before and after the hide wash intervention, throughout the beginning, middle, and end of the production day (n = 10 swabs/sampling point/timepoint). A total of 171 boot swab samples were also simultaneously taken at the end of the production day by walking from the front to the back of the pen in a pre-determined ‘Z’ pattern to monitor the pen floor environment from 3 different locations in the lairage area. The prevalence of pathogens was analyzed using the BAX® System Real-Time PCR Assay. There were no significant reductions observed for Salmonella and/or any Shiga toxin-producing E. coli (STEC) on the hides after the bacteriophage application (p > 0.05). Escherichia coli O157:H7 and O111 hide prevalence was very low throughout the study; therefore, no further analysis was conducted. However, boot swab monitoring showed a significant reduction in E. coli O157:H7, O26, and O45 in the pen floor environment (p < 0.05). While using Finalyse as a pre-harvest intervention in the lairage areas of commercial beef processing facilities, this bacteriophage failed to reduce E. coli O157:H7 on the hides of beef cattle, as prevalence was low; however, some STECs were reduced in the lairage environment, where the bacteriophage was applied. Overall, an absolute conclusion was not formed on the effectiveness of Finalyse and its ability to reduce E. coli O157:H7 on the hides of beef cattle, as prevalence on the hides was low.