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The Roles of Ammonia, Water Activity, and pH in the Salmonellacidal Effect of Long-Used Poultry Litter
P. C. B. Turnbull and G. H. Snoeyenbos
Vol. 17, No. 1 (Jan. - Mar., 1973), pp. 72-86
Published by: American Association of Avian Pathologists
Stable URL: http://www.jstor.org/stable/1588921
Page Count: 15
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Lyophilized salmonella cells exposed to atmospheres of 3 different water activities ( a w) showed negligible death rates at very low a w both without ammonia and with ammonia at 100 to 400 μg/ml air. Apart from some variation among the 3 serotypes tested, death rates increased as a w was raised from approximately 0.5 to values approaching 1.00. Ammonia added to these atmospheres accelerated the death rates. Relations between death rate, a w, and ammonia were similar in litter contaminated with Salmonella typhimurium. A number of samples of old and new litter were assayed for ammonia, moisture, pH and salmonellacidal activity. The highest activity obtained was a decrease of S. typhimurium from 9.2× 109 cells/5 g of litter to zero recovery within 11 days. The appearance of salmonellacidal activity in a sample of litter under test was observed to be accompanied by a rapid rise in ammonia and pH. In general, moisture, ammonia, and pH increased with the period of litter use, and salmonellacidal activity was a result of 2 principal factors: a w unfavorable to salmonella cell viability; and high pH from ammonia dissolved in the available moisture of the litter.
Avian Diseases © 1973 American Association of Avian Pathologists