Table 3. Tabulated detection resultsa and survey weighted detection resultsb (in bracket) for Salmonella sp. shed in feces of culled cows sampled on six California dairies based on culture and combined PCR-culture testing of enriched brot.
| Sample type | Testc | Number of samples | All Herd | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Culture | PCR-Cultured | Herd 1 | Herd 2 | Herd 3 | Herd 4 | Herd 5 | Herd 6 | ||
| Individual cow | + | + | 0 (0) | 0 (0) | 3 (11) | 21 (104) | 2 (3) | 28 (65) | 54 (183) |
| + | − | 1 (4) | 1 (2) | 1 (4) | 1 (6) | 1 (2) | 1 (3) | 6 (21) | |
| − | + | 0 (0) | 0 (0) | 0 (0) | 0 (0) | 0 (0) | 0 (0) | 0 (0) | |
| − | − | 39 (136) | 39 (68) | 36 (95) | 18 (80) | 37 (55) | 11 (32) | 180 (466) | |
| Fecal pool | + | + | 0 (0) | 0 (0) | 3 (10) | 6 (29) | 2 (3) | 7 (17) | 18 (59) |
| + | − | 0 (0) | 0 (0) | 0 (0) | 0 (0) | 0 (0) | 0 (0) | 0 (0) | |
| − | + | 0 (0) | 0 (0) | 0 (0) | 0 (0) | 0 (0) | 0 (0) | 0 (0) | |
| − | − | 8 (28) | 8 (14) | 5 (12) | 2 (9) | 6 (9) | 1 (3) | 30 (75) | |
| Broth pool | + | + | 0 (0) | 0 (0) | 2 (7) | 8 (38) | 2 (3) | 7 (17) | 19 (65) |
| + | − | 0 (0) | 0 (0) | 1 (4) | 0 (0) | 0 (0) | 0 (0) | 1 (4) | |
| − | + | 0 (0) | 0 (0) | 0 (0) | 0 (0) | 0 (0) | 0 (0) | 0 (0) | |
| − | − | 8 (28) | 8 (14) | 5 (11) | 0 (0) | 6 (9) | 1 (3) | 28 (65) | |
Notes.
a
Actual data representing the total number of cows randomly identified and sampled at each dairy.
b
Data was expanded based on the sampling weights (total number of cows available for sale on a given sampling day/number of cows randomly identified and sampled) to adjust for the studys survey sampling.
c
+, Positive; −, Negative.
d
Results of enriched broth of fecal samples tested in series using PCR for Salmonella invA gene followed by culture when testing positive or inconclusive by PCR.