An in vitro investigation of the survival and/or growth of Campylobacter jejuni in broiler digestate from different feed types.

Campylobacter spp. is the leading cause of bacterial gastroenteritis worldwide and poultry are the primary reservoir. The aim of this study was to investigate the survival and/or growth of Campylobacter jejuni NCTC 11168 in broiler digestate prepared from commercial starter, grower and finisher feed formulations. Bolton broth and digestates were prepared, inoculated with C. jejuni NCTC 11168 (approximately 3 log10 CFU per ml) and incubated under microaerobic conditions at 42°C for 24 h. Samples were taken at t = 0 (immediately after inoculation) and every 3 h thereafter, serially diluted and plated onto mCCDA. Campylobacter jejuni grew as expected in Bolton broth (control) reaching the early stationary phase after approximately 15 h. In contrast, although bacterial concentrations were maintained for at least 9 h, none of the feed digestates supported the growth of C. jejuni, which were not detected after 15 h. It is suggested that the nutrients available in the feed digestates are not enough to support C. jejuni growth and that additional factors may be at play in the avian gastrointestinal tract.

An investigation of broiler caecal Campylobacter counts at first and second thinning.

AIMS: The objectives of this study were the following: (i) to investigate if Campylobacter negative flocks at first thinning remain negative at second thinning; (ii) to determine if the caecal counts in birds infected during first thinning remain lower than in birds that were positive at first thinning; and (iii) to determine if reducing the time between first and second thinning to a maximum of 4 days would reduce both the incidence and prevalence of broiler caecal contamination. METHODS AND RESULTS: Twenty-two flocks were tested at first and second thinning using ISO methodologies. Of the 14 that had a 4-day duration between first and second thinning, nine flocks were Campylobacter negative at first thinning. By second thinning, all 14 flocks were positive and Campylobacter counts ranged from 5·5 to 6·6 log(10) CFU g(-1) regardless of the status at first thinning. The other eight flocks were all Campylobacter positive at first thinning with counts ranging from 0·8 to 6·1 log(10) CFU g(-1) which increased to 5·1 to 6·9 log(10) CFU g(-1) by second thinning (3-10 days). PCR speciation and MLST genotyping suggested the majority of isolates were Camp. jejuni belonging to STs 257, 814, 6763 and 6764. CONCLUSIONS: It was concluded that; thinning introduces Campylobacter into broiler flocks; caecal counts in birds at second thinning are similar, regardless of flock status at first thinning and reducing the time between first and second thinning to a maximum of 4 days is not an effective control strategy. SIGNIFICANCE AND IMPACT OF THE STUDY: This study informs Campylobacter control strategy at primary production, suggesting all post-first thinning broilers should be treated as 'high risk' regardless of Campylobacter status at first thinning or duration between first and second thinning.