TABLE 2.

Overview of the THRS counts in the different samples from dairy farms and at three different incubation temperatures (psychrotolerant, mesophilic, and thermotolerant aerobic spore-forming bacteria)a

Sample (no. of isolates)% THRSa
20°C37°C55°C
NDe≤10>10-≤102>102ND≤10>10-≤102>102-≤103>103ND≤10>10-≤102>102-≤103>103
Raw milk (CFU ml−1)
    Total (18)55.644.488.911.116.777.85.6
Milking machine (CFU swab−1)
    Teat cups (33)87.912.178.818.23.078.818.23.0
    Cluster (12)100.050.041.78.375.08.316.7
    Connection point pipeline (6)100.050.050.083.316.7
    Filter cloth (2)b50.050.050.050.050.050.0
    Collection tank (11)100.072.727.381.818.2
    Total (64)92.26.31.667.226.63.13.176.615.66.31.6
Green crop (CFU g−1)
    Ensilage (12)75.025.066.716.78.38.358.333.38.3
    Green maize (15)100.086.76.76.780.06.76.76.7
    Hay/straw (5)100.020.020.020.020.020.040.060.0
    Other (4)c75.025.0100.025.050.025.0
    Total (36)88.98.32.872.211.15.65.65.655.625.013.95.6
Fodder (CFU g−1)
    Feed concentrate (25)56.016.016.012.024.012.032.028.04.020.012.020.032.016.0
    Pulp (2)100.050.050.050.050.0
    Other (5)d60.020.020.020.040.020.020.040.040.020.0
    Total (32)59.415.612.512.525.015.631.325.03.118.815.625.028.112.5
  • a THRS counts, selecting for potentially highly heat-resistant spores, are expressed as percentages of the samples belonging to a given spore content category after heating at 100°C for 30 min. The numbers of samples analyzed per category of sample are shown in parentheses.

  • b The whole filter cloth was recovered for sampling; therefore, concentration is expressed as CFU g−1 for this sample category.

  • c Other samples included lucerne, chopped corn, grass, and ensiled beetroot and leaves.

  • d Other samples included soy (2), soy mixed with linseed, cereals, and a mixture of wheat, barley, and linseed.

  • e ND, none detected.