Evaluation of the Lactic Acid Fermentation Process for Elimination of Mycobacteria from Wastelage

Nine cultures of mycobacteria (four avium , two bovis , one paratuberculosis , one smegmatis , one phlei ) and one culture each of Salmonella typhimurium and Escherichia coli were placed in formulated rations of bovine manure, poultry litter, and corn forage. Rations were ensiled in polyethylene bags at 25 degree C, and survival of the cultures was ascertained. All cultures incubated in bovine manure silage and corn silage rations were eliminated by the 5th day of ensiling, but all survived in the poultry litter silage for 15 days. High buffering capacity of litter silage was responsible for failure of the silage to achieve a low pH similar to other silages. All nine mycobacteria test cultures grew in lactic acid-acidified Dubos medium at and above pH 4.6, but none grew below pH 4.3. Salmonella typhimurium and Escherichia coli were eliminated from manure-formulated silages when the pH decreased to 4.5 or less; however, a pH of 4.3 or less was required to eliminate mycobacteria.