Research Note: Effect of a phlorotannin extract of the brown seaweed Ascophyllum nodosum as a potential control strategy against Campylobacter in broilers.

Poultry is generally recognized as the main source of human campylobacteriosis and Campylobacter is highly prevalent at the farm level. To reduce the relative risk of human campylobacteriosis attributable to broiler meat, it is necessary to reduce Campylobacter loads in broiler ceca but to date, no effective, reliable and practical strategy is available. The marine environment is a rich source of original natural compounds exhibiting different biological activities. The objective of this study was to test a phlorotannin extract of the brown seaweed Ascophyllum nodosum as a potential control strategy against Campylobacter in broilers. Bactericidal activity has been demonstrated in vitro, on several Campylobacter spp. strains at a range of 0.06 to 0.47 mg/mL. Therefore, an in vivo trial in experimental facilities was performed to evaluate addition of 0.2% (w/w) of an A. nodosum extract to feed distributed at the end of rearing from day 31 to day 35, and to assess the effect on artificial Campylobacter jejuni colonization. No statistical differences in Campylobacter enumeration were observed between the treated and control groups. Another trial was performed in a commercial broiler flock. Feed containing the extract at 0.2% (w/w) (2 kg/t) was distributed during the last 5 days of rearing (day 33-day 38). No significant effects on Campylobacter colonization and on growth parameters were observed compared to the control group. Additional studies are needed to assess whether active polyphenols are found in the cecum.

Randomized control trial to test the effect of a feed additive on Campylobacter contamination in commercial broiler flocks up to slaughter.

A randomized controlled trial (RCT) was carried to evaluate the effect of a feed additive on Campylobacter contamination of broilers reared in commercial conditions. Twenty-four broiler flocks naturally contaminated with Campylobacter were enrolled in the RCT: 12 were assigned to a control group (C) fed with a conventional finishing feed from 4 weeks of age to slaughter (around 35 days), and the other group of 12 flocks (S) was fed with a finishing feed supplemented with 250 ppm of a patented feed additive (an ion-exchanged clay compound) previously proven to reduce Campylobacter contamination in broiler caeca under experimental conditions. Enumeration of Campylobacter colonies in caeca (8 per flock) was carried out following ISO standards before feed distribution and at slaughter. Before treatment, the caecal Campylobacter load tended to be lower in C flocks (7.1 ± 1.9 log CFU/g, CI95% [6.6-7.5]) than in S flocks (7.7 ± 1.0 log UFC/g, CI95% [7.5-7.9]) (p = .05). At slaughter, the bacterial load was similar in the S (7.7 ± 1.0 log CFU/g, CI95% [7.5-7.9]) and C groups (7.5 ± 1.2 log CFU/g, CI95% [7.2-7.8]) (p = .73). Therefore, the feed additive had no significant effect on the caecal Campylobacter load at slaughter under the tested conditions. The logistical constraints inherent in field trials and the natural variability of Campylobacter contamination in naturally infected broiler flocks make it difficult to reproduce experimental results in in situ farm conditions. RCT testing of an intervention strategy in commercial situation is therefore a key step in evaluating pre-harvest interventions against food-borne pathogens.

Control strategies against Campylobacter at the poultry production level: biosecurity measures, feed additives and vaccination.

Campylobacteriosis is the most prevalent bacterial foodborne gastroenteritis affecting humans in the European Union, and ranks second in the United States only behind salmonellosis. In Europe, there are about nine million cases of campylobacteriosis every year, making the disease a major public health issue. Human cases are mainly caused by the zoonotic pathogen Campylobacter jejuni. The main source of contamination is handling or consumption of poultry meat. Poultry constitutes the main reservoir of Campylobacter, substantial quantities of which are found in the intestines following rapid, intense colonization. Reducing Campylobacter levels in the poultry chain would decrease the incidence of human campylobacteriosis. As primary production is a crucial step in Campylobacter poultry contamination, controlling the infection at this level could impact the following links along the food chain (slaughter, retail and consumption). This review describes the control strategies implemented during the past few decades in primary poultry production, including the most recent studies. In fact, the implementation of biosecurity and hygiene measures is described, as well as the immune strategy with passive immunization and vaccination trials and the nutritional strategy with the administration of organic and fatty acids, essential oil and plant-derived compound, probiotics, bacteriocins and bacteriophages.

Efficacy of feed additives against Campylobacter in live broilers during the entire rearing period: Part B.

A total of 636 day-of-hatch Ross 308 broilers chicks were used in 4 independent trials carried out to screen the effect of 12 feed additives on reducing cecal colonization of Campylobacterin broilers. The tested additives were probiotics based on B. subtilis and S. cerevisae, a garlic extract, a blend of herbal substances and essential oils, two different combinations of essential oils and organic acids (OA), two mixtures of flavoring compounds, medium chain fatty acids (MCFA), monoglycerides (MG) of MCFA and MG-MCFA+OA. At 14 days of age, all the birds were orally infected with 0.1 mL of a bacterial suspension of C. jejuni ST-45 diluted at 10(5) cfu/mL in tryptone salt broth. In each trial, there was a positive control group and 2 (Trials 1 and 2) or 4 (Trials 3 and 4) additional treatment groups supplemented with additives, which were added to feed or water only to the finisher (21 to 42 d) diet (Trials 1 and 2) or to the starter (0 to 21 d) and finisher diets (Trials 3 and 4). Feed and water were available ad libitum. On days 35 and 42 of age in Trials 1 and 2, and on days 21, 35 and 42 of age in Trials 3 and 4, 10 (Trials 1 and 2) or 12 birds (Trials 3 and 4) per group were euthanized for cecal sampling. In Trial 1, birds fed with MCFA and MG-MCFA had a significant (P<0.05) reduction in cecal Campylobacter colonization compared to control at 35 d, but only the group treated with MG-MCFA maintained the reduction at 42 d. In Trials 2 to 4, no significant differences (P>0.05) in cecal Campylobacter counts were found between the treated and control animals. In conclusion, although none of the treatments were able to completely prevent the colonization of chickens with C. jejuni, MCFA and MG-MCFAs could reduce the pathogen counts when supplemented from 21 days onwards.

Efficacy of feed additives against Campylobacter in live broilers during the entire rearing period.

Poultry meat is the major source of human campylobacteriosis, the most frequently reported zoonosis in the EU. The prevalence of Campylobacter colonization in European broiler flocks is 71%. Despite considerable efforts, there is still no effective strategy available to prevent or reduce Campylobacter colonization in broilers. This study tested a wide variety of feed additives to reduce Campylobacter shedding in primary poultry production. Twelve additives containing organic or fatty acids, monoglycerides, plant extracts, prebiotics, or probiotics were tested. For each additive, broilers contaminated with Campylobacter jejuni were fed with an additive free diet (control group) or with a supplemented diet (treated group) and Campylobacter loads compared at three sampling times. No treatment was able to prevent broiler colonization by Campylobacter, and there was a high degree of variation in contamination among the birds. At 14 d of age, eight treatments significantly decreased the colonization level compared to the control group by a maximum of 2 log10 CFU/g. At 35 d of age, three of these treatments still had a significant effect with a maximum reduction of 1.88 log10 CFU/g for a probiotic. At 42 d of age, only one short-chain fatty acid was still significantly efficient with a mean reduction over 2 log10 CFU/g. In addition, a probiotic and a prebiotic-like compound significantly decreased the contamination by a maximum of 3 log10 CFU/g, only at the 42-d sampling period. This study gives promising results regarding the use of feed additives to reduce Campylobacter infection in flocks. Nevertheless, a global approach, combining intervention measures at the different steps of the broiler meat production chain could have a greater impact on the reduction of public health risk.