Performing Department
Population Health & Reproduction
Non Technical Summary
Mixed crop-livestock farms (i.e. bio-diversified farms) are farms where animals and crops are raised with the goal of utilizing the products of one for the growth of the other. Mixed produce growers in northern California have diversified their production system to include a rotation of livestock in order to manage plant biomass, add manure to the soil, and increase products produced on the farm. These systems face challenges, including potential food safety risks and compliance with third-party audit criteria. Furthemore raw manure from grazing animals may introduce foodborne pathogens such as Campylobacter, into fields, and these pathogens can persist in the soil for extended periods of time. There is limited data defining the microbial risk or adequate waiting period after animals are grazed on a produce field. Moreover, little scientific data exist regarding the risk of inter-species transmission and resulting risk to microbial contamination of fresh produce crops. The goal of this study is to investigate the prevalence of Campylobacter spp, on farms integrating livestock and produce production by rotational grazing, and source track potential movement of strains between species (cattle-poultry; swine-poultry and small ruminants-poultry). This project will provide critical information that can be incorporated into guidelines aimed toward developing best practices on risk mitigation of foodborne pathogens for mixed crop-livestock farms with rotational grazing sytem.
Animal Health Component
100%
Research Effort Categories
Basic
(N/A)
Applied
100%
Developmental
(N/A)
Goals / Objectives
The goal of this study is to investigate the prevalence of Campylobacter spp, on farms integrating livestock and produce production by rotational grazing, and source track potential movement of strains between species (cattle-poultry; swine-poultry and small ruminants-poultry). The specific objectives are: 1) To determine the prevalence of Campylobacter spp. in livestock in mixed crop-livestock farms with rotational grazing of 2 different species (cattle-poultry; small-ruminants, swine-poultry); 2) To assess the inter-species transmission risk of Campylobacter genotypes in livestock sharing rotational grazing fields. 3) To assess the persistence of Campylobacter in the farm environment (compost, water troughs) and produce crops.
Project Methods
A 4 month longitudinal study will be conducted in mixed crop-livestock farms with rotational grazing in farms located in two regions of California (Northern California and Central Valley), which are representative of the recent growth of this production system. The inclusion criteria for farm selection are: 1) farm incorporates crop-livestock and rotational grazing system; 2) small to medium-sized farms; 3) livestock species: cattle-poultry, swine-poultry and small ruminants-poultry; 4) comparable management practices (pasture and rotational grazing) 5) pasture fields to be used in produce crops and 6) willingness to participate. Ten farms will be enrolled (3 farms are already enrolled in an on-going study have shown willingness to participate in this present project). The outcome of interest is the prevalence of Campylobacter in ruminants, swine and poultry. Farms will be visited for a period of 4 months and animals and farm environment will be repeated sampled every month. A total of 480 samples will be collected during study period (12 samples/visit X 4 months X 10 farms), including individual fecal samples (ruminants/swine), composite fecal samples (poultry), drag swabs, water, compost and produce samples. All samples will be cultured for Campylobacter spp and isolates will be subtyped by sequencing the porA gene that encodes the major outer membrane protein ("MOMP typing"). The association between potential risk factors (e.g., demographics, management practices, animal health, biosecurity) and Campylobacter prevalence will be calculated using generalized linear mixed models. Multiple sequence alignment will be used to compare genetic relationships between Campylobacter strains from livestock and other environmental samples.