Prevalence, concentration and genotypes ofCampylobacter jejuniin faeces from dairy herds managed in farm systems with or without housing

Abstract

To determine the faecal excretion of Campylobacter jejuni by dairy cows that used housing in combination with outdoor grazing. Campylobacter jejuni prevalence and concentration were measured in a total of 990 cow faecal samples collected from seven herd home farms (HH), seven stand-off pad farms (SOP) and seven pasture farms (P) over a 2-year period. On all the farms, cows had access to pasture but were restricted to narrow grazing strips in winter. The overall Camp. jejuni prevalence was 55, 49 and 54% on HH, SOP and P farms, respectively. The Camp. jejuni concentration ranged from 0 to 6·7 log10 g(-1) faeces and was not statistically different among the farm systems. However, Camp. jejuni prevalence (P = 0·014) and concentration (P = 0·0001) were significantly greater in winter and early spring after intensive use of HH, SOP and strip-grazing. Typing of 30 Camp. jejuni isolates revealed a dominance of ruminant types (MLST CC-61, CC-21, CC-42 and CC-48), which are associated with human disease. No overall difference was observed among systems, but seasonal management practices that force cows close together increased the prevalence and concentration of Camp. jejuni in faeces. These findings are important when identifying farm practices that reduce Camp. jejuni excretion and the associated risk to human health.