SALMONELLA IN ANIMAL SLURRY CAN BE DESTROYED BY AERATION AT LOW-TEMPERATURES

Cattle and other animals infected by Salmonella can emit high numbers of these bacteria. To determine an effective means for reducing this b acterial group in animal slurry, samples were subjected to aeration in laboratory experiments and in farm-scale slurry tanks. A clear reduct ion in Salmonella levels tvas found in laboratory experiments at tempe ratures from 4 to 40 degrees C. Aeration in farm-scale slurry tanks in creased the temperature above the ambient temperatures (often less tha n 0 degrees C) to maxima ranging between 19 and 40 degrees C. Farm-sca le aeration resulted in similar reductions in Salmonella as those achi eved in laboratory experiments. Thus, reductions, ranging from greater than 99% of the initial number to no detectable Salmonella, could be reached after 2-5 weeks using aeration processes with cattle slurries contaminated by Salm. infantis or pig slurry contaminated by Salm, typ himurium. These results suggest that farmers can control the spread of Salmonella from slurry to agricultural fields. The reduction mechanis ms remain unknown, though the increase in pH (to 7.6-9.0) found in slu rries after aeration might exert a decreasing effect on these bacteria .