Table 6.
Final binomial GEE model with an exchangeable correlation structure, a logit link function, and robust standard errors, for the predicted prevalence of Trichostrongylid-type and Nematodirus spp. eggs in fresh environmental fecal samples collected from 3567 cows, calves, and heifers from 199 herds from western Canada sampled between 2012 and 2014.
| Trichostrongylid-type | Nematodirus spp. | |||||
|---|---|---|---|---|---|---|
|
|
|
|||||
| Odds ratio | P-value | 95% CI | Odds ratio | P-value | 95% CI | |
| Year | ||||||
| 2012 | Ref | Ref | ||||
| 2013 | 0.36 | 0.00 | 0.22 to 0.58 | 0.25 | 0.00 | 0.14 to 0.44 |
| 2014 | 0.53 | 0.02 | 0.32 to 0.90 | 0.41 | 0.02 | 0.19 to 0.87 |
| Season | ||||||
| Summer | Ref | Ref | ||||
| Fall | 0.33 | 0.00 | 0.17 to 0.65 | 2.17 | 0.01 | 1.23 to 3.82 |
| Animal class | ||||||
| Cows | Ref | Ref | ||||
| Calves | 0.84 | 0.58 | 0.45 to 1.56 | 10.73 | 0.00 | 5.00 to 23.04 |
| Replacement heifers | 1.12 | 0.68 | 0.65 to 1.93 | 1.11 | 0.83 | 0.42 to 2.91 |
| Season by Animal class | ||||||
| Fall by Cows | Ref | |||||
| Fall by Calves | 4.52 | 0.00 | 1.76 to 11.58 | |||
| Fall by Replacement heifers | 3.34 | 0.03 | 1.13 to 9.90 | |||
CI — confidence interval.