Indigenous feed microflora and Salmonella typhimurium marker strain survival in poultry mash diets containing varying levels of protein

The effect of varying concentrations of different protein sources on the su rvival of a Salmonella typhimurium marker strain resistant to both novobioc in and nalidixic acid in nonsterile poultry mash diets was determined. A dr y inoculum containing a primary poultry isolate of S. typhimurium was used to evaluate survival in mash containing one of two protein sources, soybean meal or meat and bone meal, at five concentrations (100, 150, 200, 250 and 300 g crude protein kg(-1) mash) and stored at room temperature (21+/-1 de grees C) for 56 days. In general, aerobic enumerations recovered from diets containing meat and bone meal were greater than those from diets containin g soybean meal excluding day 0 and 56 (P<0.05). During the 56-day period a reduction by approximately 0.5 log(10) colony forming units Salmonella g(-1 ) mash was observed. The differences of Salmonella survival between soybean and meat and bone meal based diets was not consistent among 10 sampling po ints. No significant differences of either aerobic bacterial populations or Salmonella were observed for the five concentrations of protein for each s ource (P greater than or equal to 0.05). However, large numbers of this org anism survived at all protein concentrations well beyond typical storage ti mes. (C) 1998 Elsevier Science B.V.