PMC

Differences between Salmonella strains regarding acid tolerance in pelleted feed. Recovery of the S. Infantis strain or the S. Typhimurium strain in pelleted feed with or without exposure to 1% acid following 1, 48 or 144 h incubation. The data points are based on the combined data from samples treated with formic acid or a mixture of formic and propionic acid (80%:20%) in trials 3 and 4.

Effect of strain, acid type and feed material on the survival of Salmonella. Recovery of the S. Senftenberg, S. Typhimurium, S. Infantis and S. Putten strains in different feed materials at different time points without (dashed lines; c = control) or with (solid lines) exposure to 1% formic acid or a mixture of formic and propionic acid (80%:20%) following 1, 48 or 144 h incubation.

Effect of commercial blends of acids on the survival of Salmonella in feed materials. Recovery of Salmonella in acid treated feed materials. Compound mash feed (A, B) and soybean meal (C, D) were pre-treated with 0.9 or 1.5% of Amasil or Luprocid respectively, and inoculated with the S. Infantis strain (A, C) or the S. Typhimurium strain (B, D). Samples were collected at 0, 1, 4, 7, 14, 21 and 28 days plated on TSA followed by XLD overlay (c = control).

Effect of temperature on acid induced reduction in Salmonella. (A) Recovery of the S. Typhimurium strain and the S. Infantis strain in rapeseed meal with or without exposure to 1% formic acid at 5°C, 15°C and room temperature (~23°C) after 1, 48 and 120h (c = control). (B) Reduction in Salmonella in feed materials as function of accumulated temperature (temp*time). Data are pooled for rape seed meal and soybean meal.

Effect of organic acids on the survival of Salmonella in rape seed meal. Recovery of the S. Typhimurium strain and the S. Infantis strain in rapeseed meal at different time points without exposure to acid (control) or exposed to 1% formic acid (FA) or a 1% mixture of formic and propionic acid (FA/PA) (80%:20%). The points show the mean values for two separate experiments with three replicate samples for each of the Salmonella strains. The lines show the fitted Weibull models with the following parameters C: N₀=−0.53 log₁₀ CFU/ml (SE 0.14), Δ= 359 h (SE 357 h), p=0.28 (SE 0.14). FA: N₀=−0.98 log10 CFU/ml (SE = 0.14); Δ=24.40 h (SE 12.4 h), p= 0.34 (SE 0.08). FA/PA: N₀=−0.98 log₁₀ CFU/ml (SE 0.14), Δ=18 h (SE 8.5), p=0.31 (SE 0.12).