Table 1.
Statistical models used to study associations between outcome variables and herd antibody status
| Outcome variable | Data type | Model type | Explanatory variables1 |
|---|---|---|---|
| Milk yield | Continuous | Linear | a, b, n |
| BTMSCC2 | Continuous | Linear | a, b, n, p |
| Calving interval | Continuous | Linear | a, b, n, p, i |
| Calving to first AI3 | Continuous | Linear | a, b, n, p, i |
| Number of AI3 | Continuous | Linear | a, b, n, p, i |
| Dead calves 0-24 hours | Binomial | Logistic | a, b, n |
| Culling | Binomial | Logistic | a, b, n, p |
| UDS4 ≥6 | Binomial | Logistic | a, n |
1 a = antibody status, b = breed, n = herd size, p = milk production level, i = artificial insemination strategy
2 bulk tank milk somatic cell count.
3 artificial insemination
4 udder disease score, see main text for explanation.