USE OF LACTIC ACID BACTERIA FOR DECONTAMINATION OF PIG STYLE BY EXPERIMENTAL SILAGE

Swine production generates every day a large amount of residues, including nutrients and microorganisms, which potentially contribute to contamination of air, water and soil, and generation of unpleasant odors. Many strategies have been developed in order to mitigate the contaminant effect of swine manure and to take advantage of its nutrients and beneficial compounds; silage is an example of these, and consists in swine manure fermentation mainly under anaerobic conditions. The aim of this study was to assess the effect of applying a process of silage to swine manure added with two different sources of carbohydrates and two different sources of lactic-acid bacteria, under the reduction of different microbiological indicators. Through the process, it was observed the reduction of pH levels (until reaching 4.6) and microbial content, mainly for coliforms (reduction greater than 5 log), molds and yeasts, and total elimination of enterococci. On the other hand, significant decline was not reported for the lactic-acid bacteria content, main responsible of fermentation process. Best results were observed through using sorghum as a source of carbohydrates and cheese whey as a source of lactic-acid bacteria, for both, decrease of pH and reduction of some microbiological indicators, including bacteria that produce sulfuric acid. Therefore, silage process, applied to swine manure, induces the decrease of pH for action of lactic-acid bacteria until limit the survival of bacteria associated with fecal contamination, making of swine a transformed and microbiologically safe residue for its handling and subsequent use.