Effect of Ammonia Gas in Poultry Litter Contaminated with Salmonella Heidelberg

Salmonella Heidelberg is an emerging pathogen in Brazilian poultry production. The traditional methods (quicklime, windrowing and tarpaulin-on-surface) used for disinfecting reused poultry litter between flocks does not guarantee its elimination, thus allowing the transmission of this agent from one flock to another. The new tarpaulinon-surface method with controlled injection of ammonia gas has proven to be effective in its control, however, it is still unknown what dose of ammonia gas is needed to eliminate Salmonella Heidelberg in reused poultry litter. The objective of this study was to evaluate the effect of ammonia gas at different concentrations in sterile poultry litter artificially contaminated with Salmonella Heidelberg. Then, ammonia gas was injected in concentrations of 0.25%, 0.5%, and 1%, and 48 hours later, a sample was collected from each repetition in an entirely randomized design, and bacterial isolation was performed. All treatments, including positive and negative controls, were tested in quadruplicate and the parameters temperature, humidity, pH and water activity were evaluated. In the 0.5% and 1% treated samples the pathogen was not isolated, while in the 0.25% concentration one of the four samples tested was positive. The study reveals that ammonia gas is efficient in killing Salmonella Heidelberg in poultry litter at concentrations of 0.5 % or more within a 48-hour period and that the litter treated with ammonia gas increases its pH and water activity.