Survivability of indigenous microflora and a Salmonella typhimurium marker strain in poultry mash treated with buffered propionic acid

Abstract

Buffered propionic acid (BPA) was evaluated as a potential treatment for the elimination of Salmonella spp. in poultry mash. A primary poultry isolate marker strain of Salmonella typhimurium was added as either a broth or in a dry chalk carrier form to poultry mash containing soybean meal as a protein supplement. The mash was supplemented with buffered propionic acid at 2, 4, 6, 8, 10, 20, 30, 50 and 100 g kg −1 diet and samples were enumerated for indigenous aerobic bacteria, fungi and the S. typhimurium marker strain. Total indigenous aerobic bacteria and fungal populations were generally decreased by addition of more than 20 g BPA kg −1, but an addition of 100 g BPA kg −1 mash was usually required to achieve reductions of approximately 90% of indigenous aerobic bacteria and 99% of indigenous fungi. After 7 days of storage, 8 g BPA kg −1 mash also reduced S. typhimurium populations by more than 90% in mash inoculated via chalk, while at least 50 g BPA kg −1 mash was required to provide the same level of reduction in mash inoculated with a liquid culture of S. typhimurium. Although BPA does not appear to be an overly effective antimicrobial agent with respect to indigenous aerobic bacterial populations in animal feed, higher concentrations may have the potential for reducing fungal and Salmonella spp. contamination in poultry mash.