Changes in the microbiological quality of manure from laying hens after drying and during storage

Abstract

that may be used to treat manure from laying hens and the physicochemical composition and microbiological quality of treated chicken manure, with the main standards used being NF U 44-051 and NF U 42-001. The main treatment applied to chicken manure is drying. Changes in the temperature, dry matter contents and microbiological quality of chicken manure after treatment using three different drying methods (Seconov, tunnel and pre-drying via ventilation shafts) and during subsequent storage in hangars were monitored, and the influence that the different drying methods appeared to have on these parameters was assessed. Microbiological analyses of manure samples included counts of faecal streptococci (enterococci), salmonellae, Escherichia coli, Clostridium perfringens (vegetative and sporulated), Listeria monocytogenes and helminth eggs. The Seconov drying process was very efficient in drying manure, thus reducing the nuisances (e.g. odour, flies) associated with storing this product. However the result of this rapid drying was that during storage the manure did not achieve the high temperatures necessary to kill harmful bacteria. Even after four months of storage, populations of enterococci, E. coli and C. perfringens in manure treated with the Seconov process were still above acceptable limits. Whereas the tunnel drying and pre-drying methods were less effective in removing moisture from chicken manure, the significant increases in manure temperature achieved after several days of storage meant that acceptable microbiological levels (meeting the requirements of standard NF U 44-051) were achieved within 2-2.5 months.