Table 1 List of Potential Risk Factors (PRFs) selected for screening process
PRF | Explanation | Comments |
|---|---|---|
total cattle | Total number of cattle on the farm on sampling day | Continuous |
management type | Cattle management type the respondent indicated as primary system on the farm | Categorical, 4 levels; Dairy (used as baseline level in the analysis); Other, Suckler Beef; Specialist Finisher. |
AHDa | Animal Health Division – a non-current geographical designation in Scotland | Categorical, 6 levels |
cattle 12–30 months | Total number of cattle on the farm aged between 12 and 30 months on sampling day | Continuous |
cattle less than 1 year | Total number of cattle on the farm aged under 1 year on sampling day | Continuous |
group size | Total number of cattle in the sample group | Continuous |
oldest in group | Age (months) of the oldest sample group animal | Continuous |
youngest in group | Age (months) of the youngest sample group animal | Continuous |
season | Calendar year divided into three-month periods with March–May = spring, etc. | Categorical, 4 levels: Autumn (used as baseline level in the analysis); Winter, Spring; Summer |
housed | Whether the sample group was completely housed or had access to grazing | Dichotomous; baseline “grazing” |
feed changed | Whether or not the sample group’s feed had changed in the 2 weeks before sampling | Dichotomous; baseline “no” |
location changed | Whether or not the sample group were moved in the 2 weeks before sampling | Dichotomous; baseline “no” |
cattle brought on (CBO) | Whether or not cattle were moved on to the farm in the year before sampling | Dichotomous; baseline “no” |
breeding females brought on (BFBO) | Whether or not breeding female cattle were moved onto the farm in the year before sampling. | Dichotomous; baseline “no” |
fatteners brought on (FBO) | Whether or not fattening cattle had been moved onto the farm in the year before sampling. | Dichotomous; baseline “no” |
livestock on farm not owned by farmer | Whether or not there were livestock of any species present on the day of sampling, which were not owned by the respondent (e.g. over-wintering sheep) | Dichotomous; baseline “no” |
bought other livestock | Whether or not any livestock (not cattle) had been purchased in the year before sampling | Dichotomous; baseline “no” |
cattle elsewhere | Whether or not employed farm workers caring for cattle on the sampled farm could also come into contact with cattle through work or family/friends elsewhere. | Dichotomous; NotApp answers categorised as “no”; baseline “no” |
non mains water | Whether or not sampled cattle had access to non-mains water | Dichotomous; baseline “no” |
organic | Whether or not routine farm practice was to spread cattle manure or slurry on grazing/silage ground | Dichotomous; NotApp answers categorised as “no”; baseline “no” |
wild geese | Whether or not flocks of 100 or more geese had been seen on fields to which cattle have access | Dichotomous; baseline “no” |
gulls | Whether or not flocks of 100 of more gulls had been seen on fields to which cattle have access | Dichotomous; baseline “no” |
ewes | Whether or not there were breeding ewes present on the farm on sampling day | Dichotomous; baseline “no” |
surveyb | Whether or not the survey was conducted in Scotland or in England & Wales | Dichotomous; baseline “no” |
stx statusc | Indicating which Shiga toxins were present in faecal pat samples collected from a positive farm | Categorical, 3 levels: stx1&stx2_neg (baseline); stx1neg_stx2pos; stx1&stx2pos |
percent posc | The percentage of all faecal pat samples collected from a positive farm, which tested individually positive for E. coli O157 | Continuous |