Abstract
The effect of silage fermentation on activity of Mycobacterium avium sub sp. Paratuberculosis was studied using small scale fermentation system. M. avium sub sp. paratuberculosis was added to milled and sterilized alfalfa hay with 80% (w/v) sterilized isotonic saline, and lactic acid bacteria or formic acid were used as additives for the silage preparation. When stored at 5℃ for 14 days, all of the silage were poor preserved, with high pH value and low lactic acid content. The counts of M. avium sub sp. paratuberculosis were high in these silages. When stored at 30℃ or 37℃ for 14 days, all of the silages were well preserved, with low pH value and high lactic acid content. The counts of M. avium sub sp. paratuberculosis decreased at a level that was not detectable. The tolerance of M. avium sub sp. paratuberculosis to formic acid, lactic acid, acetic acid, propionic acid and butyric acid were 0.05, 0.10, 0.05, 0.10 and 0.30%(w/v), respectively. After 7 days of incubation with 0.50% organic acid solution, cell form of that bacteria was changed. However, M. avium sub sp. paratuberculosis showed activity in these organic acid solutions those were adjusted using 30%(w/v) NaOH to pH 6.5. The results confirmed that the fermentation products of silage effectively inhibit the survival of M. avium sub sp. paratuberculosis, and the well-preserved silage could not become a resource of Jhones' disease. However, that in the poor-fermented silages with high pH value and low lactic acid content could become a resource of that disease.
