Browsing by Subject "Escherichia coli O157:H7"
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Item Effects of live cultures of Lactobacillus acidophilus (strains NP45 and NP51) and Propionibacterium freudenreichii on performance, carcass and intestinal characteristics, and Escherichia coli 0157:H7 shedding of finishing beef steers(Texas Tech University, 2003-05) Elam, Nathan AndrewIn Exp. 1, 240 beef steers (British and Continental; initial BW = 332.8 ± 23.1 kg) were used to determine the effects of live cultures of Lactobacillus acidophilus (LA) and Propionibacterium freudenreichii (PF) on performance, carcass and intestinal characteristics, and prevalence of Escherichia coli 0157:H7 (EC) shedding during the finishing phase. Cattle were fed a steam-flaked corn-based, 92% concentrate diet for an average of 170 d. The four direct-fed microbial (DFM) treatments included: (1) control, lactose carrier only (Red); (2) 1x10^ 9 cfu of LA Strain NP51 plus 1 x 10^6 cfu of LA Strain NP45 plus 1 x 10^9 cfu of PF NP24 per animal daily (Green); (3) 1 x 10^9 cfu of LA Strain NP51 plus 1 x 10^9 cfu of PF NP24 per animal daily (Yellow); and (4) 1x10^6 cfu of LA Strain NP51 plus 1x10^6 cfu LA Strain 45 plus 1 x 10^9 cfu of PF NP24 per animal daily (Blue). A randomized complete block design was used with pen as the experimental unit (12 pens/treatment). No differences {P > 0.10) among treatments were detected for final BW, DMI, ADG, feed:gain (F:G), and hot carcass weight. In addition, dressing percent, longissimus muscle area, fat thickness at the 12th rib, percentage of internal fat, and yield grade did not differ (P > 0.10) among treatments. A difference {P = 0.08) among treatments was detected for ileal lamina propria (LP) thickness. The average LP thickness for Yellow and Green steers was less (P < 0.05) than the average for Red and Blue steers (0.38 vs. 0.45 mm). Moreover, Yellow and Green steers had a lower (P < 0.10) incidence of EC shedding than Red and Blue steers. Overall, these data indicate that under the conditions of this study live cultures of LA plus PF did not greatly affect feedlot performance and carcass characteristics. Some of the cultures decreased fecal EC shedding, which might be related to the results for ileal LP thickness. In Exp. 2, 660 steers were used to determine the effects of live cultures of LA and PF on performance, carcass, and intestinal characteristics of feedlot finishing steers. Cattle were fed a steam-flaked corn-based, 91% concentrate diet for an average of 118 d. Treatments included: (1) control, lactose carrier only (Red); (2) 5 x 10^6 cfu of LA Strain NP51 plus 5 X 10^6 cfu of LA Strain NP45 plus 1 x 10^9 cfu of PF NP24 per animal daily (Blue); and (3) 1 x 10^9 cfu of LA Strain NP51 plus 5 x 10^6 cfu LA Strain NP45 plus 1x10^9 cfu of PF NP24 per animal daily (Yellow). The steers used in this trial were from two distinct backgrounds. Background Group 1, classified as a short days on feed group (average BW at arrival = 352 kg), had grazed before arrival (BGl), and Background Group 2, classified as a long days on feed group (average BW at arrival = 314 kg), had been in a grower yard before arrival (BG2). As such, a split-plot design was used with background source as the whole-plot factor and DFM treatment as the split-unit factor. The overall F for background classification was significant (P <0.03) for both final BW and DMI; however, relative to DFM treatment no differences (P >0.67) were detected for DMI or BW data. The interaction for background classification and DFM treatment was significant (P <0.08) for both ADG and carcass-adjusted ADG. The simple effect ADG means and carcass-adjusted ADG means for all DFM treatments were different (P <0.01) between the two background classifications. In addition, within BGl DFM treatments were different (P = 0.09) for ADG; DFM treatments Red and Blue were not different (P = 0.70) from each other, but both were different (P <0.08) from Yellow. Carcass-adjusted ADG was not different (P >0.23) for any DFM treatment within a background classification. As within ADG, the interaction of background classification and DFM treatment was significant (P <0.08) for both F:G and carcass-adjusted F:G. In contrast, the simple effect F:G means and carcass-adjusted F:G means for all DFM treatments were not different (P >0.12) across or within a background classification. Grade fat, taken at the 3/4 measure opposite the split lean surface between the 12th and 13th ribs was significantly different (P = 0.03) for DFM treatments. The interaction between background source and DFM treatment was significant (P <0.04) for both marbling score and the quality grade data. The simple effects for the Blue DFM treatment were different (P <0.01) across background source for both variables. The percentage of Choice vs. Select (42.51 vs. 57.49%, respectively) in BGl was reversed (64.20 vs. 35.80% respectively) in BG2. No other carcass characteristics relative to DFM treatment were different (P >0.24). The DFM treatments did not affect (P = 0.82) lamina propria thickness in cecal samples taken directly adjacent to the ileocecal junction. Overall, these data indicate that under the conditions of this study some of the live cultures of LA plus PF increased ADG in cattle that were classified as a short days on feed group. Furthermore, the DFM treatments used in this study did not alter LP thickness as in Exp. 1.Item Efficacy of Beef Carcass Surface Trimming to Reduce or Eliminate Escherichia coli O157:H7 Surrogates from Subsequent Subprimals(2012-02-14) Laster, Brittany AniseThis study was conducted to determine the effectiveness of trimming the original external carcass surfaces from subprimals during fabrication on the reduction of surrogates for Escherichia coli O157:H7. Carcass sides from five cattle (n = 10 sides) were inoculated along the pattern hide opening before entering the blast chill cooler with a gelatin slurry containing a bacterial cocktail of three rifampicin-resistant, nonpathogenic E. coli Biotype I strains. Following a 48 h chill, sides were fabricated to produce eight subprimals (brisket, chuck, clod, rib, bottom round, top sirloin, short loin, and inside round). Microbiological samples were taken from the original carcass fat surface area, initial lean surface area, trimmed fat surface area (where applicable), and trimmed lean surface area (where applicable). Trimming of the external fat surfaces reduced (P < 0.05) microbiological counts on the newly exposed lean surfaces of all eight subprimals during fabrication. However, these data also indicated that fat and lean surfaces that were not initially exposed to contamination became contaminated during the fabrication process. Trimming external surfaces reduces levels of pathogens, but under normal fabrication processes, pathogens may still be spread to the newly exposed surfaces.Item Epidemiological Investigation of Risk Factors for Microbial Contamination in Produce at the Preharvest Level(2013-11-15) Park, SangshinIn the United States, the proportion of outbreaks of microbial foodborne illnesses associated with fresh produce has increased over the past decades. A large proportion of these outbreaks have been caused by enteric pathogens, including Listeria monocytogenes, Salmonella, and Escherichia coli O157:H7. The overall objective of this dissertation was to study the risk factors for preharvest produce contamination with these three pathogens and generic Escherichia coli, as an indicator organism of fecal contamination, to improve control of foodborne illnesses associated with fresh produce. This objective was accomplished through three independent studies. The first study identified and characterized known risk factors for contamination of fruits and vegetables at the preharvest level with L. monocytogenes, Salmonella, and E. coli O157:H7 by conducting a systematic review. The review identified and evaluated 68 published research articles which indicated soil and irrigation water as the most important routes of produce contamination with pathogens. The review indicated the existence of solid evidence for several additional risk factors, including growing produce on clay-type soil, the use of contaminated or non-pH-stabilized manure fertilizer, and the use of spray irrigation with contaminated water, with a particular risk of contamination on the lower leaf surface. A total of 955 spinach samples were collected from 12 spinach farms in Colorado and Texas for the second and third study. The second study evaluated the effect of farm management and environmental factors on spinach contamination with generic E. coli at the preharvest level. The results indicated that spinach contamination was influenced by the time since last irrigation, the use of pond water for irrigation, workers? personal hygiene, the use of the field prior to planting, and the proximity of a poultry farm. The third study evaluated the role of weather and landscape factors, in addition to the farm management and environmental factors, in occurrence of spinach contamination with generic E. coli at the preharvest level. The results indicated that spinach contamination was influenced not only by the amount of rain, but also by workers? personal hygiene, the use of the spinach field prior to planting, and the use of manure fertilizer. In conclusion, the three studies have identified important risk factors for microbial contamination of produce at the preharvest. The control of several of these risk factors has already been the focus of the currently established Good Management Practices (GMP) in produce production. The novel findings suggest that the GMP may need to account for rainfall and improve workers? personal hygiene in order to further reduce produce contamination with microorganisms.Item Epidemiology of Bacterial Food-borne Pathogens: Linking Intermittent Pathogen Shedding and Transmission in Their Animal Hosts(2013-04-30) Gautam, RajuMost bacterial foodborne pathogens are shed intermittently from their animal hosts and are able to grow and persist in the environment. Cattle and pigs constitute the major animal reservoirs for these pathogens. The overall objective of this dissertation research was to improve understanding of the role of intermittent shedding and environmental persistence in the transmission and maintenance of Escherichia coli O157:H7 and Salmonella Typhimurium in their animal host populations. This objective was addressed through five interdepended studies. The study in Chapter II, describes the transmission of E. coli O157:H7 in a dairy herd using mathematical modeling that includes indirect transmission from the contaminated environment. The model predicts that the elevated ambient temperature during summer, together with the availability of large amount of drinking water per cattle, are the major factors for increased pathogen load in water and high prevalence of E. coli O157:H7 in cattle populations. The second study, in Chapter III, determined the variation in water-to-cattle ratios among feedlot pens and evaluated the association with the pen level management and environmental factors. Water-to-cattle ratio was found to vary greatly between feedlots and pens with lower water-to-cattle ratios on average had cooler drinking water. The study in Chapter IV, used a compartmental mathematical model of infection transmission, to evaluate the effect of cleaning on Salmonella Typhimurium control in a grower-finisher pig herd. Cleaning alone was not found to be an effective measure of control unless combined with other measures to reduce the level of bacterial shedding. The study in Chapter V, developed the multi-state Markov chain model to describe the fecal shedding pattern of three E. coli O157:H7 strains in cattle. One strain was not detected to shed, while the other two strains had on average different durations of host colonization, albeit not at the statistically significant level. The study in Chapter VI, used an experimental infection transmission approach to estimate and compare transmission rates for three different strains of E. coli O157:H7 in steers. The results revealed that the transmission rate of E. coli O157:H7 increases significantly with increasing levels of environmental contamination. Collectively, the five studies have highlighted the role of these pathogen characteristics in their transmission. The improved understanding of these characteristics will allow for better design of control measure to ensure food safety.Item Prevalence and distribution of Escherichia coli O157 among finishing beef cattle supplemented with Lactobacillus-based direct-fed microbials(Texas Tech University, 2003-12) Dahl, Spring Marie YountsEscherichia coli 0157 has emerged as a prominent food-borne pathogen that is associated with cattle and consumption of beef products. The objectives of this research were: (1) to quantify the prevalence of E. coli 0157 in feces and on hides of finishing beef cattle fed a standard diet and those fed diets supplemented with Lactobacillus acidophilus-based direct-fed microbials (DFM); and (2) to describe the dynamics of within-pen prevalence of fecal shedding ofE. coli 0157 among finishing beef cattle supplemented with the DFM. The DFM used in supplemented diets included various combinations and concentrations of two strains of Lactobacillus acidophilus (NP 51 and NP 45) and Propionibacterium freudenreichii. Overall, cattle receiving a 1 x l09 CFU/steer daily of NP 51 throughout the feeding period were 57% less likely to be shedding a detectable level of E. coli 0157 in their feces compared with those receiving the control diet. When each pen sampling was considered an independent observational unit, zero or one out of five steers were found to be shedding E. coli 0157 in 84% of within-pen prevalence observations. Fecal shedding of E. coli 0157 was not associated with hide contamination on either the pen or individual animal level. The decrease in the overall prevalence of fecal shedding of E. coli 0157 among cattle receiving a high-level dose of NP 51 was a function of a decrease in both the number of animals per pen that were positive and the number of pens with at least one positive animal. Supplementing cattle with Lactobacillus acidophilus strain NP 51 may be an efficacious intervention strategy to control E. coli 0157 in the pre-harvest environment.Item Reduction of Escherichia coli O157:H7 and salmonella following application of various sanitizing treatments to harvesting knives(2012-08) Tapp, William N.; Miller, Markus F.; Brashears, Mindy M.; Brooks, ChanceEscherichia coli O157:H7 (E. coli O157:H7) and Salmonella are enteric pathogens that can cause severe illness and possible death if consumed. These pathogens are potential contaminants to meat during animal harvest. If not properly sanitized, knives used during this process can become a vehicle to spread contamination of these pathogens from carcass to carcass during the harvest process. The purpose of this study was to assess the effectiveness of non-thermal sanitation along with changes to treatment application interval, while evaluating E. coli O157:H7 and Salmonella reduction on knives. Chemical dip treatments included, 1.1% sodium metasilicate (SMS), 200 ppm quaternary ammonium compounds (QAC), 200 ppm chlorine (Cl2), 5% lactic acid (LA), 82.2°C water (HW), and 21°C water (RTW). Three replications of 18 knives were processed after inoculation of both E. coli O157:H7 and Salmonella (separately) to show initial and treated pathogen survival on a CFU/cm2 basis. Knife blades were inoculated with a three strain cocktail of either E. coli O157:H7 or Salmonella. A single side of the knife blade was sampled with a sponge, which was pre-hydrated with 10 ml of a neutralizer specific to the sanitizing treatment; in the case of water treatments sponges pre-hydrated with buffered peptone water (BPW) were used for sampling. Thirty second immersion treatments in sanitizing solutions were applied. The other side of the knife blade was sampled just as pre-treated sides to evaluate reduction. Dilutions of E. coli O157:H7 samples were plated onto MacConkey agar, and Salmonella sample dilutions were plated onto Xylose Lysine Desoxycholate media. Arithmetic means of pathogen numbers on untreated knives inoculated with E. coli O157:H7 and Salmonella showed an attachment of 4.51 and 5.09 log CFU/cm2, respectively. Treatment * time interaction of least square (LS) mean log reductions of knives inoculated with E. coli O157:H7 were 1.16, 3.51, 3.38, 1.38, 3.82, and -0.41 CFU/cm2, following treatment in SMS, QAC, Cl2, LA, HW, and RTW, respectively (P ≤ 0.05). Furthermore, treatment * time interactions of knives inoculated with Salmonella resulted in LS mean log reductions of 0.78, 3.42, 3.40, 2.91, 4.12, and 0.36 CFU/cm2, following treatment in SMS, QAC, Cl2, LA, HW, and RTW, respectively (P ≤ 0.05). Results depict that utilization of sanitizing agents in ambient temperature water treatments have potential to provide significant reduction of E. coli O157:H7 and Salmonella on knives used during animal harvest.Item Simulation of Contamination Through the Post-Harvest Environment Using Surrogate Organisms(2011-10-21) Villarreal Silva, MarianaThe beef industry has made tremendous strides in reducing pathogen contamination on carcasses. Multiple antimicrobial interventions have been validated for their use during harvesting. Information in regards to cross-contamination with pathogens in the post-harvest environment is limited. Surrogate microorganisms for enteric pathogens are commonly used to validate antimicrobial interventions and might allow for the simulation of cross-contamination through the post-harvest environment. The purpose of this study was to determine how the post-harvest environment impacts the direct and indirect transmission of pathogens. This was achieved by using fluorescent protein-marked surrogate strains of Escherichia coli O157:H7 and Salmonella spp. from inoculated carcasses to the adjacent ones and to the equipment and facility in three different abattoirs. Thirteen hide-on carcasses were inoculated using a gelatin-based slurry containing three nonpathogenic fluorescent protein-marked strains of E. coli biotype I. In order to determine direct and indirect cross-contamination, inoculated and adjacent carcasses were sampled (300 cm2) during the harvesting process at different stages: after hide opening (AHO), prior to evisceration (PE), after evisceration (AE), after splitting (AS), and after final intervention (AFI). Environmental samples consisting of the floor, walls, and air were tested as well as personal equipment including gloves, boots, and aprons. Equipment including hand knives, air knives, meat hooks, hide puller and split saw were also sampled. Results showed evidence of cross-contamination between inoculated carcasses and the adjacent non-inoculated ones for all abattoirs. Although this occurred in all abattoirs, surrogate counts on carcasses were below detectable levels (<1.4 log CFU/cm2) after antimicrobial interventions. Surrogates were found in low levels for all environmental samples. However surrogate counts from equipment such as knives, split saws, meat hooks, and hide puller were more frequently detected (15 percent) than those found on the floor, air and walls samples (10 percent). In the case of aprons, boots, and gloves, the prevalence of countable surrogate samples was 7 percent.Item Survival and distribution of Escherichia coli O157 in bovine manure(Texas Tech University, 2004-12) Echeverry, AlejandroEscherichia coli 0157:H7 has become one of the most important emerging foodborne pathogens with many recent outbreaks being associated with cattle. Although estimates of E. co//0157:H7 prevalence in cattle have increased over time likely due improvements in detection methodologies, fecal collection methodologies and sample transport conditions from farm to microbiological laboratories for further analysis may be factors for underestimation of prevalence of this pathogen. In this study, a new sampling methodology was analyzed and comparison of survival of E. coli 0157:H7 in feces of cattle under various experimental conditions was also determined. For the first part of the study, bovine fecal samples were inoculated with a cocktail of four different antibiotic resistant E. co//0157:H7 strains. Each inoculated sample was subdivided and subjected to each of the four following conditions: 37°C, room temperature (23''C), refrigeration temperature (4.4°C) and in plastic coolers with refrigerant packs in order to simulate transportation conditions. Samples from each of the temperature conditions were taken at 0 h, 24 h, 48 h, 120 h, and 144 h and subjected to detection and quantification of E. coli 0157:H7. Overall, holding samples at temperatures equal to or below to 23° C resulted in detectable populations for up to 168 h. At 37°C, samples were not recovered by any of the methods used after 48 hours. These results indicate that holding samples at room temperature or lower for up to 168 h prior to processing will not reduce the pathogen's population. For the second part of the study, the objective was to evaluate fecal pat sampling strategies to improve accuracy of E. co//0157:H7 prevalence estimates. A total of 120 fresh fecal pats from cattle were used in this study. From each fecal pat five samples were collected systematically going from West to East (positions 1 to 5 respectively) in north to south lines direction to avoid cross contamination and cultured for E. coli 0157:H7 within two hours using IMS separation. Of the 120 fecal pats, 96 (80%) had no positive samples in any of the 5 samples. One sample was positive in 13 of the pats, 2 in 4 of the pats, 3 in 2 of the pats, 4 in 3 of the pats and only 2 of the pats had all 5 samples positive. Of the 600 total sub-samples analyzed, 49 were positive with 14, 9, 8, 8, and 10 on position 1,2,3, 4, and 5 respectively. An increase in the prevalence of 2.45-fold (from 8.17% to 20%) was observed when sampling 5 positions per fecal pat as compared to the estimated prevalence obtained when just 1 sub-sample was obtained. Prevalence estimates may be underestimated as a result of an uneven distribution in fecal material; therefore sampling procedure plays a critical role in E. co//0157:H7 detection in bovine fecal pats.Item Technique differences to enumerate and isolate E. coli O157:H7 and the use of ozonated water to eliminate E. coli(Texas Tech University, 1999-12) Carr, Mandy AnnettThe objectives of this study were to compare the currently suggested method by USDA and a procedure including immunomagnetic separation for sensitivity in detecting E. coli 0157:H7 on beef hide samples when time before enrichment and sample handling procedures were varied; and to determine the effect of ozonated water bath treatments on the survivability of a non-pathogenic strain of E coli (ATCC 25922) on inoculated beef fat samples. The effects of time/handling practices and detection method utilized a 2 method X 3 time/handling factorial. Three sponges were hydrated with sterile buffer and each used to aseptically sample a 7.6cm X 38cm area of beef hide. The sponges were aseptically halved and placed in sterile sampling bags. A total of 30 animals were sampled on 5 days. Samples were randomly assigned to a treatment group of Method 1 - Immediate (Ml-I), Method 1 - Delayed Chilled (Ml-DC), Method 1 - Delayed Room Temperature (Ml-DRT), Method 2 - Immediate (M2-I), Method 2 - Delayed Chilled (M2-DC), or Method 2 - Delayed Room Temperature (M2-DRT). Immediate samples began enrichment within 4 h of sampling. Delayed samples were placed in an ice chest with icepacks (DC) or without icepacks (DRT), and stored at room temperature for 28 h. Method 1 used traditional procedures accepted by the USDA utilizing the BioControl Assurance EIA EHEC test kit for screening. Method 2 utilized the Dynal anti-0157 magnetic bead technique. The Dynal anti-0157 beads in Method 2 appeared to increase the likelihood of finding samples containing microorganisms that were confirmed by O agglutination compared to the technique in Method 1 (77.8 vs. 8.9%). Immediate testing found 26 O agglutination positive samples compared to 22 positive samples by both DC and DRT. All O positive samples from Method 1 were non-identifiable with the api 20 E test. However, of the 70 positive samples after O agglutination in Method 2, 25 (35.7%) were identified as E. coli. E. coli 0157:H7 was not found in any sample. Within Method 2, if enrichment was initiated immediately, 66.7% of samples were identified with a genus name. If enrichment was delayed, storing with ice packs (DC) enabled 36.7% to be identified compared to 30.0% if the samples were stored at room temperature (DRT) before sampling. The ozone study utilized a 2 inoculation level X 3 time treatment factorial arrangement of a randomized block design, with day as the block, to determine the effect of an ozonated water bath system on the survival of £. coli (ATCC 25922). ORP readings of 650 to 700 millivolts were utilized throughout the study. Five beef fat samples were used for each treatment on each day. Samples inoculated with 10 CFU/ml E. coli exposed to 0 min were not different (P > .05) from samples in the bath for 10 or 60 seconds (5.66, 5.38, and 5.38 log10 CFU/cm^, respectively). Samples inoculated with 10^ CFU/ml exposed for 0 min were different (P < .05) from samples in the bath for 10 or 60 seconds (3.02, 2.81 and 2.53 log10 CFU/cm^, respectively), but counts from the two bath treatments were not different (P > .05). These results indicate that the current air, water and OPR settings were not effective to eliminate E. coli (ATCC 25922).Item The effects of a trichloromelamine wash on Escherichia coli O157:H7 and Salmonella spp. prevalence on beef hides(Texas Tech University, 2003-12) Sultemeier, Crystal MicheleIn a multi-stage experiment, the efficacy of Trichloromelamine (TCM), a chlorine-containing disinfectant compound, on the reduction of Escherichia coli 0157:H7 and Salmonella spp. on beef hides at an abattoir was determined. Twenty head of cattle were sampled on each of two consecutive days of each week during a six-week period. A preliminary swab was taken from each head immediately following exsanguinations. Cattle were then sprayed with TCM and a second swab was taken immediately prior to hide removal. Swabs were then analyzed for prevalence of E. coli 0157:H7 and Salmonella spp.. In a second trial, swabs were taken both prior to and following treatment. Treatment in this trial included TCM and TCM plus a thickening agent (TCM + T), with ten head receiving each treatment. In a third experiment, individual hide samples were spread with fecal slurries which were inoculated with K coli 0157:H7 and Salmonella spp.. Hide samples were sprayed with TCM or TCM + T and allowed a dwell time of 1 to 10 minutes. E. coli and Salmonella spp. were then enumerated for each hide sample. In the first trial, significant decreases were seen for E. coli 0157JI7 (P < 0.0002) and Salmonella spp. (P < 0.0001). No significant decreases were observed for E. coli 0157:H7 in the second trial due to a small number of preliminary positives. Significant decreases in Salmonella spp. were seen from TCM and TCM + T treatments (P < 0.0001). A significant difference was also observed between TCM and TCM + T treatments with TCM + T having a greater reduction (P < 0.05). In the enumeration study, significant log reduction was not seen for E coli 0157:H7 for either treatment. Both treatments exhibited a significant log reduction (P < 0.0001). Results of this study indicate TCM is an effective in-slaughter means of microbial intervention.Item The effects of whole cottonseed on performance, carcass characteristics, and shedding characteristics of Escherichia coli O157 by finishing beef steers(Texas Tech University, 2003-12) Cranston, Jacob JohnOne hundred twenty crossbred beef steers (initial body weight = 230.3 ± 18.0 kg) were used to determine the effects of whole cottonseed (WCS) supplementation on performance, carcass characteristics, and the prevalence of Escherichia coli 0157 in the feces and on hides at slaughter of finishing beef steers. The three dietary treatments included: (1) a standard finishing diet (STD); (2) a diet containing 15.10% whole cottonseed (WCS): and (3) a whole cottonseed equivalent diet (EQU) formulated to contain percentages of fat and neutral detergent fiber (NDF) equal to those in the WCS diet. Cattle were on feed for an average of 120 d. A randomized complete block design was used with pen as the experimental unit (eight pens/treatment). Results reported here are for the period from d 0 to slaughter. A difference among treatments was detected for dry matter intake (DMI; P = 0.056). Steers fed the WCS diet consumed more feed than steers fed the STD or EQU diets (P < 0.091). No differences were detected among treatments for average daily gain (ADG; P = 0.521), carcass-adjusted ADG (P = 0.305), or feed efficiency, expressed as feed:gain. (P = 0.225); however, a difference was detected among treatments for carcass-adjusted feed efficiency (P = 0.009). Separation of the treatment means revealed that cattle fed the STD treatment used feed more efficiently (P < 0.01) on a carcass-adjusted basis than steers fed the WCS or EQU diets. No differences (P > 0.10) were detected among treatments for hot carcass weight, fat thickness at the 12"' rib, longissimus muscle area, percentage of kidney, pelvic, and heart fat, liver abscess score, and USDA yield and quality grades. Differences were detected among treatments for dressing percent (P = 0.061) and marbling score of the longissimus muscle (P = 0.058). Steers fed the STD diet had higher dressing percents (P < 0.058) than steers fed the WCS and EQU diets. Additionally, steers fed the STD diet had higher marbling scores (P < 0.081) than steers fed the WCS and EQU diets. No differences were detected (P > 0.229) among treatments for the presence of £. coli 0157 detected at any sampling period during the study. These results indicate that unless an adjustment is made for total dietary fiber, finishing cattle fed a diet containing supplemental WCS will likely consume more feed and gain similarly to cattle fed a standard finishing diet. These data also indicate that WCS will likely have no effect on the prevalence of £. coli 0157 in beef cattle.Item The use of lactic acid bacteria as a post-harvest intervention to control escherichia coli O157:H7 in fresh spinach(2008-12) Gragg, Sara E.; Brashears, Mindy M.; Brooks, Chance J.; Miller, Markus F.; Thompson, Leslie D.In recent years, fresh spinach has been identified as a vehicle for Escherichia coli (E. coli) O157:H7 transmission. Multiple studies have demonstrated the ability of lactic acid producing bacteria (LAB) to reduce the presence of Escherichia coli O157:H7 in food products and the efficacy of LAB cultures as a post – harvest intervention in fresh spinach production should be evaluated. To determine the effect of spinach inoculated with Escherichia coli O157:H7, spinach samples were rinsed with sterile distilled water and a four – strain LAB cocktail at a target concentration of 2.0x108 CFU/mL. Both treatments were compared to an inoculated control over a 24 – hour time period at 7oC. According to composite LS means data obtained for each treatment, water and LAB resulted in significant reductions of 0.88 logs (p<0.0001) and 1.03 logs (p<0.0001) in comparison to the control, respectively. The improved reduction of LAB was significantly better than that of water (p=0.0363), making it the most effective treatment. A triangle test was conducted to determine if a statistically significant difference in sensory characteristics exists when LAB is applied to fresh spinach. Two samples were rinsed with tap water and considered to be identical. The remaining sample was rinsed with LAB at a concentration of 2.0x108 CFU/mL. 40 panelists participated in the test and 16 correctly identified the LAB – treated spinach as being the one unique sample. These results indicate that a statistically significant difference does not exist (á=0.05, 0.01) when LAB is applied to fresh spinach and that the use of LAB may be acceptable from a consumer acceptance standpoint. The ability of LAB to control E. coli O157:H7 populations in combination with the industry standard chlorine rinse was determined in a 12 day shelf – life study at 7oC. The multi – hurdle intervention was evaluated in comparison to water, LAB and chlorine rinses. LAB cultures were applied at a concentration of 2.0x108 CFU/mL, while chlorine was utilized at the 200 ppm level. As indicated by composite LS means data, significant reductions in comparison to control populations were achieved by the LAB (p=0.0215), chlorine (p=0.0002) and multi – hurdle treatments (p<0.0001). However, the multi – hurdle treatment produced the greatest reductions with 1.35 logs. This reduction was significantly improved upon LAB (p=0.0012) and chlorine (p=0.0815), indicating that the application of chlorine and LAB is most effective as a combination treatment.Item Validation of processing parameters for the production of microbiologically safe cooked ready-to-eat and raw meat products(2006-05) Mann, Jason E.; Brashears, Mindy M.; Francisco, Michael J. D. S.; Alvarado, Christine Z.; Loneragan, Guy H.Recent outbreaks of foodborne illness have resulted in increased regulatory pressure on meat processors. Validation of production processes to determine their ability to produce microbiologically safe finished product has been emphasized. Control of pathogen growth in raw products and pathogen lethality during heat processing of cooked ready-to-eat (RTE) products are important. Cross contamination of carcass surfaces with bacteria, including pathogens such as Salmonella and Escherichia coli O157:H7, can occur during animal harvest. Sources of contamination include the digestive tract and hide of the animal and the processing environment. Raw meat products are not generally subjected to interventions during processing that reduce bacterial counts. Therefore, it is necessary to control the growth of bacteria on the product during processing. Control of product and/or processing environment temperature is generally the only available means to control bacterial growth. Control of bacterial growth in raw meat for use in the production of cooked RTE meat products is less important than in product to be sold in the raw state. Safety of cooked RTE products depends on proper cooking. Thermal processing parameters should be designed to result in a Salmonella lethality that meets or exceeds regulatory performance standards. Parameters of interest include oven temperature, product internal temperature, processing time and process humidity. The purpose of the studies performed was to determine the effects of environmental and product temperature on the growth of Salmonella and E. coli O157:H7 in raw meat products and also the effects of product temperature and process humidity on the lethality of surface inoculated Salmonella during the thermal processing of cooked RTE roast beef. Results suggest that meat processors can safely process raw meat products under a variety of conditions, ranging from 4.4ºC (40ºF) to room temperature (23.3ºC/74ºF) if the time of product exposure is considered relative to the product or environmental temperature. Furthermore, thermal processing of cooked RTE roast beef in the presence of humidity levels ranging from 30-90% resulted in an adequate Salmonella lethality when processed to an internal temperature of 62.8ºC (145ºF). Overall results provide parameters that can be utilized by meat processors to produce microbiologically safe finished products.Item Validation of processing parameters for the production of microbiologically safe cooked ready-to-eat and raw meat products(Texas Tech University, 2006-05) Mann, Jason E.; Brashears, Mindy M.; Alvarado, Christine Z.; Loneragan, Guy H.; Francisco, Michael J. D. S.Recent outbreaks of foodborne illness have resulted in increased regulatory pressure on meat processors. Validation of production processes to determine their ability to produce microbiologically safe finished product has been emphasized. Control of pathogen growth in raw products and pathogen lethality during heat processing of cooked ready-to-eat (RTE) products are important. Cross contamination of carcass surfaces with bacteria, including pathogens such as Salmonella and Escherichia coli O157:H7, can occur during animal harvest. Sources of contamination include the digestive tract and hide of the animal and the processing environment. Raw meat products are not generally subjected to interventions during processing that reduce bacterial counts. Therefore, it is necessary to control the growth of bacteria on the product during processing. Control of product and/or processing environment temperature is generally the only available means to control bacterial growth. Control of bacterial growth in raw meat for use in the production of cooked RTE meat products is less important than in product to be sold in the raw state. Safety of cooked RTE products depends on proper cooking. Thermal processing parameters should be designed to result in a Salmonella lethality that meets or exceeds regulatory performance standards. Parameters of interest include oven temperature, product internal temperature, processing time and process humidity. The purpose of the studies performed was to determine the effects of environmental and product temperature on the growth of Salmonella and E. coli O157:H7 in raw meat products and also the effects of product temperature and process humidity on the lethality of surface inoculated Salmonella during the thermal processing of cooked RTE roast beef. Results suggest that meat processors can safely process raw meat products under a variety of conditions, ranging from 4.4ºC (40ºF) to room temperature (23.3ºC/74ºF) if the time of product exposure is considered relative to the product or environmental temperature. Furthermore, thermal processing of cooked RTE roast beef in the presence of humidity levels ranging from 30-90% resulted in an adequate Salmonella lethality when processed to an internal temperature of 62.8ºC (145ºF). Overall results provide parameters that can be utilized by meat processors to produce microbiologically safe finished products.