Salmonella elimination during composting of spent pig litter

A windrow composting trial was carried out to investigate the effects of composting on the elimination of Salmonella from spent pig litter (a mixture of partially decomposed pig manure and sawdust). Results showed that temperature was the main factor affecting the elimination of Salmonella. At temperatures between 64 and 67°C for 2-3 weeks, the pathogen was effectively killed. The elimination of Salmonella corresponded with the progressive decrease of faecal coliforms and faecal streptococci. By the end of the composting process (day 91), the faecal coliform and streptococcal numbers were reduced to 2.27 and 2.12 Log₁₀ MPN g^-1, respectively. When these low levels are reached, the elimination of Salmonella in the spent litter is successfully achieved. The populations of faecal coliforms in all six potting media were more than twice as high as those found in the composted spent litter, indicating that although faecal coliforms were not eliminated during composting, their levels were lower than in commercial potting media.