Many diseases of farm animals, particularly salmonellosis, may be disseminated by slurry. Salmonellas may be found in low numbers (less than 100 per gram) in slurries but 90 per cent die during the first two to four weeks when the material is stored and survive on grass for short periods only. Animals experimentally allowed to graze pasture spread with slurry are not easily infected. The danger of disseminating salmonellosis by by the use of a slurry system can be significantly reduced if the slurry is stored for at least one month before spreading on pasture and if pasture treated with stored slurry is not grazed for a similar period after spreading.