TABLE 1.
Carriage rates of C. coli, C. fetus, and C. jejuni in feedlot cattle by isolation medium and sample timea
| Sample and speciesd | No. (%) of positive animals by indicated isolation mediumb
|
||
|---|---|---|---|
| mCCDA | cCCDAc | eCCDA | |
| Entry | |||
| C. coli | 9 (3.4) | 5 (0.2) | 1 (0.04) |
| C. fetus | 15 (5.6) | 258 (9.8) | 2 (0.08) |
| C. jejuni | 47 (17.7) | 97 (3.7) | 0 (0) |
| C. lanienae | 0 (0) | 1 (0.04) | 0 (0) |
| All species | 71 (26.7) | 361 (13.8) | 3 (0.1) |
| Interim | |||
| C. coli | 54 (19.8) | 12 (0.5) | 13 (0.5) |
| C. fetus | 8 (2.9) | 111 (4.3) | 0 (0) |
| C. jejuni | 110 (40.3) | 18 (0.7) | 0 (0) |
| C. hyointestinalis | 1 (0.4) | 0 (0) | 0 (0) |
| All species | 173 (63.4) | 141 (5.5) | 13 (0.5) |
| Exit | |||
| C. coli | 18 (6.5) | 7 (0.3) | 10 (0.4) |
| C. fetus | 29 (10.4) | 550 (22.0) | 0 (0) |
| C. jejuni | 130 (46.8) | 9 (0.4) | 5 (0.2) |
| C. hyointestinalis | 0 (0) | 2 (0.08) | 1 (0.04) |
| C. lanienae | 0 (0) | 2 (0.08) | 0 (0) |
| All species | 177 (63.7) | 570 (22.8) | 16 (0.6) |
| Dead | |||
| C. coli | 13 (21.3) | 5 (8.2) | 5 (8.2) |
| C. fetus | 2 (3.3) | 5 (8.2) | 0 (0) |
| C. jejuni | 6 (9.8) | 2 (3.3) | 0 (0) |
| All species | 21 (34.4) | 12 (19.7) | 5 (8.2) |
| All samples | 442 (50.3) | 1,084 (14.0) | 37 (0.5) |
In total, 7,738 fecal samples from individual animals were plated on cCCDA and eCCDA, whereas 878 samples were plated on mCCDA. See Materials and Methods for details on isolation media.
Percent values were based on the total number of animals sampled. For mCCDA, 266, 273, and 278 fecal samples were processed at the entry, interim, and exit sample times, respectively. For cCCDA and eCCDA, 2,621, 2,559, and 2,497 fecal samples were processed at the entry, interim, and exit samples times. In addition, 61 samples were obtained from animals that died during the feedlot period. The total number of isolates recovered was 1,586 (154 for C. coli, 994 for C. fetus, 431 for C. jejuni, 4 for C. hyointestinalis, and 3 for C. lanienae).
An additional 23 isolates were obtained from cCCDA (i.e., secondary cultures) and are not shown in the table.
Samples were collected upon the arrival of the cattle at the feedlot (i.e., entry sample), ca. 70 days thereafter (i.e., interim sample), and just before cattle were shipped for slaughter (i.e., exit sample). If an animal died or was shipped prematurely, a sample was also obtained.