Assessment and Validation of Pre-Harvest Management Practices to Reduce Shiga-Toxin Producing Escherichia Coli (STEC) in the Food Supply

<p>NON-TECHNICAL SUMMARY:<br/> The project is designed to enhance small-scale cattle farm competitiveness by reducing shiga-toxigenic Escherichia coli (STEC) in cattle prior to shipment to feedlots. Cattle are considered primary reservoirs of E. coli O157:H7, causing post-harvest cross-contamination of beef products. On-farm practices affect pathogen loads on cattle entering slaughter facilities. However, limited information is available on practices employed by small-scale cow/calf operations. Another limitation is effective implementation of control strategies and knowledge transfer to cattle industry. In response to this need, the project will: (1) assess production practices and determine educational gaps of small-scale cow/calf producers through survey-based research; (2) determine the factors affecting STEC prevalence on cow/calf operations; (3) establish a training
program on Best Management Practices (BMPs) and pre-harvest food-safety for cow/calf producers in Oklahoma; and (4) validate the effectiveness of on-farm BMPs in reducing STECs in the cow/calf operation environments. Survey responses and prevalence study results will drive BMP guidelines and educational workshops, addressing the problem. Effectiveness of BMPs to control the pathogens at farm level will be examined by training cow/calf producers and by following changes in pathogen loads on their farms after implementation of BMPs.
<p>APPROACH:<br/> Objective 1: Determine educational gaps and assess production practices employed by small-scale cow/calf operations through survey-based research. A needs assessment of small-scale cow/calf operations will be conducted to determine the production practices in place and the existing knowledge of farmers concerning the control of foodborne pathogens.Survey instrumentation will be developed with the expertise of the researchers involved in this project as well as outside technical experts who will evaluate the content validity of the construct area items and make recommendations for improvement. The instrument will be designed to measure participant responses in construct areas related to pre-harvest food safety issues. Knowledge and behaviors in each of the construct areas will be measured using Likert items. In addition to these two areas, important items
within each construct area will also be recorded on a Likert scale. The questionnaire will gather information on feeding practices, including details on current use of pesticides, coccidiostats, hormones, mineral and vitamin supplements, breeds of cattle, and on the knowledge that small beef cattle farmers have on the control, prevention, and transmission of STEC, in cattle and within the small farm environment.Objective 2: Determine the factors affecting STEC prevalence on small-scale cow/calf operations Based on the survey results from Objective 1,several cow/calf operations located in OK, will be selected for sample collection to determine STEC populations on the farm. Farm samples will include fecal,water, feed, bedding and soil samples, along with water equipment swabs.During the summer and fall months, samples will be collected from each farm in 2 separate sampling intervals. From
each farm a minimum of 15 fecal, 5 water or sediments, 3 each of bedding, soil, and equipment swabs will be obtained.Fecal Samples: Approximately 100g each of fecal sample will be collected from each farm where fresh fecal pats on the ground will be transferred to sterile fecal cups using either sterile gloves or spatulas. Immediately upon arrival in the laboratory, fecal sample from each farm (transported on ice packs) will be subjected to enrichment following detection, quantification and identification of STECs.Feed, Bedding and Soil Samples: Feed will be collected from the feed bunks and the feed bins on each sampling date and kept on ice until processed at the labs. Feed samples will be collected from 10 different sites of the feed bunks and bins (100 g each). Bedding samples (100 g each) will be collected from 2 locations of the stalls (10% of the stalls on each farm), maternity
pens, dry cow facilities and calf facilities (centers and one-third the distance from each external wall). Soil samples will be collected (100 g each) from 4 areas where cows/calves congregate on each farm.Water and Equipment Samples: Samples will be collected from the biofilm in the water troughs by swabbing the sides of the troughs then immediately placing the swabs in a transport medium. The sediments at the bottom of the water troughs will be collected in sterile bottles. In addition, 100ml of water will be collected in sterile bottles from the ponds located on the farms. Water samples will be analyzed for detection, isolation and enumeration of E. coli O157:H7. Equipment that comes into contact with feed or cattle's oral cavity will be sampled using a sterile spongesicle hydrated with sterile buffered peptone water (BPW).Microbiological Analysis: Detection and isolation of E.
coli O157:H7 and six serogroups of nonO157 STECs in the samples will be done using a sensitive assay that includes immuno-magnetic separation (Smith et al., 2001; Paddock et al, 2011). Molecular identification will be done using multiplex polymerase chain reaction (PCR) assay (Hu et al. 1999; Paddock et al. 2011). Quantitative concentration of E. coli O157:H7 will be determined using the method described by Brichta-Harhay et al. (2007). Results will be used to determine on-farm practices that may contribute to pathogen loads in the cattle and on the farm.Objective 3: Develop guidelines for Best Management Practices (BMPs) and pre-harvest food safety for cow/calf producers.Results from Objectives 1 and 2 will be used to determine educational gaps and to establish guidelines for BMPs that need to be implemented on these farms. These guidelines will include basic principles of cattle
management such as provision of clean feed and water, sanitary handling of water and waste, proper drainage and maintenance of the environment, and freedom from vermin and pests, along with decontamination strategies, disinfection programs, and possible use of probiotic therapies. Following the preparation of guidelines, two training workshops will be held for small-scale cattle producers in Oklahoma. These workshops will train the cow/calf operators on the following topics:Overview of pathogens and food safetyImportance of factors contributing to pathogen loads on the cattle and in the farm environment.Food safety interventionsBest Management Practices and food safetyImplementation of BMPsControl of STEC and other pathogensSignificance of cross-contamination of pathogens from cattle to other food commoditiesObjective 4: Validate the effectiveness of on-farm BMPs in reducing STEC
contamination in the cow/calf operation environments. We will validate BMPS by follow-up surveys and microbial sampling of selected farms for pathogen loads after implementation of BMPs. Following the training workshops, farms initially used to obtain samples for detection and quantification of STEC would be revisited to evaluate effectiveness of the BMPs in reducing pathogen contamination. Additionally, we will request that these selected farms implement the suggested BMPs following the training workshop.Microbial sampling will be conducted on the farms as previously described in Objective 2. The results at the end of the study will be used to determine whether the training workshop helped the cow/calf operators in effective implementation of the BMPs for controlling STECs in the cattle and on the farm environment.Data Analysis for Validation of BMPs:The data on quantification and
prevalence of E.coli O157:H7 (as log10 CFU/ml) from Objectives 2 and 4 will be combined to determine effectiveness of the treatment (BMPs). The experiment will be conducted as a repeated measures experiment in a randomized complete block design with 3 replications. Treatments will be before and after the implementation of BMPs. Farms will be the experimental units. Blocks will be farms before and after the implementation of BMPs. Since blocks will be selected to represent varied initial production practices, blocks will be considered a fixed effect. Categorical variables will be analyzed using Standard Data Categorical Analysis for Matched Pairs (Agresti, 2007). Continuous variables will be analyzed by Repeated Measures Analyses using the Mixed Model Method with special parametric structure on the covariance matrices (Littell, et al., 2006).