survival of listeria monocytogenes in wilted and additive-treated grass silage单核细胞增多性李斯特氏菌的生存在枯萎和additive-treated草青贮饲料.pdfVIP

Acta vet. scand. 2003, 44, 73-86. Survival of Listeria monocytogenes in Wilted and Additive-Treated Grass Silage 1 2 By T.M. Pauly and W.A. Tham 1Department of Animal Nutrition Management, Kungsängen Research Centre, and 2Department of Food Hy- giene, Swedish University of Agricultural Sciences (SLU), Uppsala, Sweden. Pauly TM, Tham WA: Survival of Listeria monocytogenes in wilted and additive- treated grass silage. Acta vet. scand. 2003, 44, 73-86. – Grass was field-dried to 3 dif- ferent dry matter (DM) levels (200, 430 and 540 g/kg) and inoculated with 106 7 -10 cfu/g of a Listeria monocytogenes strain sharing a phagovar occasionally involved in food- borne outbreaks of listeriosis. Formic acid (3 ml/kg) or lactic acid bacteria (8·105/g) with cellulolytic enzymes were applied only to forages with low and intermediate DM levels. Forages were ensiled in laboratory silos (1700 ml) and were stored at 25°C for 30 or 90 days. After 90 days of storage, L. monocytogenes could not be detected in any silo, except one with the high dry matter grass without additive. After 30 days of stor- age, between 102 and 106 cfu L. monocytogenes/g silage were isolated from the un- treated silages. Increasing the DM content from 200 to 540 g/kg did not reduce listeria counts possibly because of the lower production of fermentation acids (higher pH). In silages treated with additives, counts of L. monocytogenes were always lower than in silages without additive. In wet silages (DM 200 g/kg) both additives were effective, but in the wilted silages (DM 430 g/kg) only the bacterial additive reduced lister