SURVIVABILITY OF INDIGENOUS MICROFLORA AND A SALMONELLA-TYPHIMURIUM MARKER STRAIN IN POULTRY MASH TREATED WITH BUFFERED PROPIONIC-ACID

Buffered propionic acid (BPA) was evaluated as a potential treatment f or the elimination of Salmonella spp. in poultry mash. A primary poult ry isolate marker strain of Salmonella typhimurium was added as either a broth or in a dry chalk carrier form to poultry mash containing soy bean meal as a protein supplement. The mash was supplemented with buff ered propionic;dd 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 a nd Fungal populations were generally decreased by addition of more tha n 20 g BPA kg(-1), but an addition of 100 g BPA kg(-1) mash was usuall y required to achieve reductions of approximately 90% of indigenous ae robic bacteria and 99% of indigenous fungi. After 7 days of storage, 8 g BPA kg(-1) mash also reduced S. typhimurium populations by more tha n 90% in mash inoculated via chalk, while at least 50 g BPA kg(-1) mas h was required to provide the same level of reduction in mash inoculat ed with a liquid culture of S. typhimurium. Although BPA does not appe ar to be an overly effective antimicrobial agent with respect to indig enous aerobic bacterial populations in animal feed, higher concentrati ons may have the potential for reducing fungal and Salmonella spp. con tamination in poultry mash. (C) 1998 Elsevier Science B.V.