Table 2.
Mixed linear regression for age (days) of a 100-kg pig infected with influenza A(H1N1)pdm09 virus1
| Age of pig at 100 kg | SE | P-value | 95% Confidence interval | ||
|---|---|---|---|---|---|
| Predictors | Coefficients | ||||
| Infection groups | |||||
| Seronegative | 0 | — | — | — | — |
| Virus positive (33–60 kg) | 1.65 | 0.70 | 0.02 | 0.27 | 3.02 |
| Virus positive (61–80 kg) | 1.89 | 1.23 | 0.13 | −0.52 | 4.30 |
| Virus positive (81–100 kg) | 2.49 | 1.19 | 0.04 | 0.17 | 4.82 |
| Breed | |||||
| Landrace | 0 | — | — | — | — |
| Duroc | 6.15 | 0.98 | <0.001 | 4.24 | 8.07 |
| ADFI (centered) | −31.81 | 1.34 | <0.001 | −34.44 | −29.18 |
| Birthdate (centered) | −0.006 | 0.0006 | <0.001 | −0.008 | −0.005 |
| Constant β02 | 144.54 | 0.55 | <0.001 | 143.47 | 145.61 |
1The coefficients and standard errors of virus positive pigs were the parameters for Gaussian curves describing the variability between pigs on the marginal effects of infection at each of the three pig infection points: Virus positive during growth phase 1 (33 kg to 60 kg), growth phase 2 (61 kg to 80 kg) and growth phase 3(81 kg to 100 kg).
2Constant represents the age (days) at 100 kg of a seronegative Landrace pig born on 3 October 2008 with an ADFI of 2.04 kg/d.