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°C
|
37°C
|
55°C
|
||||||||||||
| NDe | ≤10 | >10-≤102 | >102 | ND | ≤10 | >10-≤102 | >102-≤103 | >103 | ND | ≤10 | >10-≤102 | >102-≤103 | >103 | |
| Raw milk (CFU ml−1) | ||||||||||||||
| Total (18) | 55.6 | 44.4 | 88.9 | 11.1 | 16.7 | 77.8 | 5.6 | |||||||
| Milking machine (CFU swab−1) | ||||||||||||||
| Teat cups (33) | 87.9 | 12.1 | 78.8 | 18.2 | 3.0 | 78.8 | 18.2 | 3.0 | ||||||
| Cluster (12) | 100.0 | 50.0 | 41.7 | 8.3 | 75.0 | 8.3 | 16.7 | |||||||
| Connection point pipeline (6) | 100.0 | 50.0 | 50.0 | 83.3 | 16.7 | |||||||||
| Filter cloth (2)b | 50.0 | 50.0 | 50.0 | 50.0 | 50.0 | 50.0 | ||||||||
| Collection tank (11) | 100.0 | 72.7 | 27.3 | 81.8 | 18.2 | |||||||||
| Total (64) | 92.2 | 6.3 | 1.6 | 67.2 | 26.6 | 3.1 | 3.1 | 76.6 | 15.6 | 6.3 | 1.6 | |||
| Green crop (CFU g−1) | ||||||||||||||
| Ensilage (12) | 75.0 | 25.0 | 66.7 | 16.7 | 8.3 | 8.3 | 58.3 | 33.3 | 8.3 | |||||
| Green maize (15) | 100.0 | 86.7 | 6.7 | 6.7 | 80.0 | 6.7 | 6.7 | 6.7 | ||||||
| Hay/straw (5) | 100.0 | 20.0 | 20.0 | 20.0 | 20.0 | 20.0 | 40.0 | 60.0 | ||||||
| Other (4)c | 75.0 | 25.0 | 100.0 | 25.0 | 50.0 | 25.0 | ||||||||
| Total (36) | 88.9 | 8.3 | 2.8 | 72.2 | 11.1 | 5.6 | 5.6 | 5.6 | 55.6 | 25.0 | 13.9 | 5.6 | ||
| Fodder (CFU g−1) | ||||||||||||||
| Feed concentrate (25) | 56.0 | 16.0 | 16.0 | 12.0 | 24.0 | 12.0 | 32.0 | 28.0 | 4.0 | 20.0 | 12.0 | 20.0 | 32.0 | 16.0 |
| Pulp (2) | 100.0 | 50.0 | 50.0 | 50.0 | 50.0 | |||||||||
| Other (5)d | 60.0 | 20.0 | 20.0 | 20.0 | 40.0 | 20.0 | 20.0 | 40.0 | 40.0 | 20.0 | ||||
| Total (32) | 59.4 | 15.6 | 12.5 | 12.5 | 25.0 | 15.6 | 31.3 | 25.0 | 3.1 | 18.8 | 15.6 | 25.0 | 28.1 | 12.5 |
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.
The whole filter cloth was recovered for sampling; therefore, concentration is expressed as CFU g−1 for this sample category.
Other samples included lucerne, chopped corn, grass, and ensiled beetroot and leaves.
Other samples included soy (2), soy mixed with linseed, cereals, and a mixture of wheat, barley, and linseed.
ND, none detected.