Table 8.
Effect of management z and year of study on minimum inhibitory concentrations (MICs) of antimicrobials for isolates of Mycoplasma bovis (n = 61). Least square means are reported for antimicrobials showing unimodal distributions (not shaded), and selected bimodal distributions (light grey shading). Arithmetic means are reported for other antimicrobials (dark grey shading). MICs < or > than the range of concentrations evaluated were estimated as the next lower or higher concentration commonly used on the Sensititre plate prior to statistical analyses.
| Antimicrobial | CON | NAT | 1 | 2 | SEM |
|---|---|---|---|---|---|
| Chlortetracycline | 4.2 | 3.3 | 3.8 | 3.6 | 0.9 |
| Enrofloxacin | 1.3 | 0.2 | 0.7 | 0.8 | 1.1 |
| Florfenicol | 4.4 | 2.9 | 3.7 | 3.6 | 0.9 |
| Gamithromycin | 239.0 b | 162.4 a | 245.9 b | 155.6 a | 12.3 |
| Oxytetracycline | 4.1 | 3.2 | 3.2 | 4.2 | 0.7 |
| Tilmicosin | 253.3 | 256.0 | 253.3 | 256.0 | NA |
| Tidipirosin | 251.1 | 256.0 | 251.1 | 256.0 | NA |
| Tulathromycin | 225.9 b | 141.3 a | 239.2 b | 128.0 a | 20.8 |
| Tylosin | 198.7 | 183.5 | 236.9 | 145.3 | 24.8 |
a,b Means within a row with different superscripts differ (p < 0.05). z Management, CON = conventional, NAT = without antimicrobials; y NA, not applicable as arithmetic mean.