Table 5.
Significant results obtained from logistic regression of antimicrobial resistant Mannheimia haemolytica from beef-type cattle upon feedlot arrival.
| Risk factor | Ampicillin | Oxytetracycline | Tilmicosin | Tulathromycin | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| OR | 95% CI | p-value | OR | 95% CI | p-value | OR | 95% CI | p-value | OR | 95% CI | p-value | ||||
| Monthly intervals | |||||||||||||||
| Aug–Nov | 1 | 1 | – | 1 | 1 | – | 1 | 1 | – | 1 | 1 | – | |||
| Dec–Feb | 0.9 | 0.2–5.0 | 0.879 | 0.6 | 0.04–7.7 | 0.689 | 1.0 | 0.1–11.0 | 0.973 | na | na | na | |||
| Mar–May | 10.0 | 1.3–76.8 | 0.027 | 17.5 | 1.1–275.9 | 0.041 | 11.6 | 1.1–121.2 | 0.040 | na | na | na | |||
| Source | |||||||||||||||
| A | 1 | 1 | – | 1 | 1 | – | 1 | 1 | – | 1 | 1 | – | |||
| B | na | na | na | 34.0 | 1.5–776.4 | 0.027 | 11.7 | 1.4–100.9 | 0.024 | 85.8 | 4.3–1,715.4 | 0.003 | |||
| RD | na | na | na | 2.6 | 0.2–34.6 | 0.433 | 4.0 | 0.7–23.6 | 0.121 | ||||||
| Mannheimia haemolytica serotype | |||||||||||||||
| A2 | 1 | 1 | – | 1 | 1 | – | 1 | 1 | – | 1 | 1 | – | |||
| A1 + A6 | na | na | na | 38.3 | 4.8–304.1 | <0.001 | 6.6 | 1.5–29.9 | 0.014 | na | na | na | |||
A, auction; B, backgrounding operations; CA, Canada; CI, confident interval; OR, odds ratio; RD, ranch direct; RF, risk factor.
na, that variable was not significant at the p-value ≤ 0.1 level and was eliminated from the regression.
Bold p-values indicate statistically significant results at p ≤ 0.1.