Susceptibility of Aeromonas hydrophila to Medium-Chain Fatty Acids and their Monoesters

Medium-chain fatty acids (MCFAs) and their monoesters were tested for their antibacterial activity against the Gram-negative pathogen Aeromonas hydrophila. The antimicrobial effect was evaluated at two temperatures (4 °C and 37 °C) using a standardized microdilution method in a 96-well microtitration plate. The minimum inhibitory concentrations of selected MCFAs were determined as the lowest concentration limiting the growth of A. hydrophila in wells compared to a positive control of ≥ 80%. The results indicated that the most effective compound against A. hydrophila was sucrose monocaprate after incubation at 37 °C (0.625 mg ml−1), whereas monocaprylin was the most effective compound after incubation at 4 °C (1.25 mg ml−1). Free MCFAs showed no antibacterial effects towards this bacterium. Low solubility and sensory properties could limit the use of fatty acids in aquatic environment, which should be the subject of further studies

Effect of Genotype on Ileal and Caecal Microbiota in Pasture-Reared Dominant Cockerels

Outdoor access is an important part of organic and free-range poultry production, yet limited information exists on the effect of various housing and production systems on the growth performance and colonization of food-borne pathogens. Therefore, the primary purpose of the current study was to evaluate the influence of different housing systems (particularly fixed versus small, portable houses, with and without outdoor access to pasture) and different broiler genotypes on the gastrointestinal bacteria in broilers. The fundamental factor studied was the presence of any quantitative changes in common gastrointestinal microbiota, including pathogenic genera such as Campylobacter sp. and Salmonella sp. The results showed differences in intestinal microbiota and confirmed lowered counts of caecal coliforms in pasture-reared broilers

Effect of coated and non-coated fatty acid supplementation on broiler chickens experimentally infected with Campylobacter jejuni

The aim of this study was to examine whether and to what extent the supplementation of feed with a coated or non-coated mixture of fatty acids (caprylic and capric acid) affects broiler chickens experimentally infected with Campylobacter jejuni. The study was carried out using 48 chickens divided into four experimental groups. Throughout the whole rearing period (1-42 days), the chickens were fed a diet supplemented with 0.25% caprylic and capric acid (1: 1), coated or non-coated. At the age of 14 and 28 days, chickens were orally challenged with C. jejuni. At regular time intervals post-inoculation, the shedding of C. jejuni was assayed using quantitative real-time PCR. Both supplements significantly decreased faecal C. jejuni counts by 1.2-4.1 log(10) CFU/g 4 days post-inoculation; after this time period, the effect of medium-chain fatty acids (MCFA) was less pronounced or absent. Campylobacter jejuni counts in excreta samples were significantly lower in chickens fed coated MCFA than in those fed non-coated MCFA. No effect of MCFA on feed intake or growth of chickens was observed. In conclusion, (i) MCFA are active against C. jejuni and (ii) the encapsulation enhanced the efficacy of the acids. These results allow the recommendation of using MCFA as feed additives in chickens, preferably 2-3 days before slaughter

Efficacy of malic acid against Listeria monocytogenes attached to poultry skin during refrigerated storage

This work evaluated the effect of malic acid washing on the growth of Listeria monocytogenes on poultry legs stored at 4°C for 8 d. Fresh inoculated chicken legs were dipped into a 1 or 2% malic acid solution (vol/vol) for 5 min or distilled water (control). Surface pH values, sensorial characteristics (odor, color, texture, and overall appearance) and L. monocytogenes, mesophile, psychrotroph, and Enterobacteriaceae counts were evaluated after treatment (d 0) and after 1, 3, 6, and 8 d of storage at 4°C. Legs washed with 2% malic acid showed a significant (P < 0.05) inhibitory effect on L. monocytogenes compared with control legs, with a decrease of about 1.66 log units after treatment. Sensory quality was not adversely affected by malic acid. Treatments with malic acid reduced bacterial growth and preserved reasonable sensorial quality after storage at 4°C for 6 d. This study demonstrates that, although malic acid did reduce populations of L. monocytogenes on poultry, it did not completely inactivate the pathogen. The application of malic acid may be used as an additional hurdle contributing to extend the shelf life of raw poultry. © 2013 Poultry Science Association Inc