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