Table 3.
Australia in 2016. Multiple linear regression model outputs of factors influencing daily milk yields in does on a large dairy goat enterprise in south western Victoria
| Variable | Coefficient (SE) | t | p value | 95% CI |
|---|---|---|---|---|
| Intercept | 2.38 (0.11) | 21.26 | < 0.001 | 2.15 to 2.59 |
| qPCR status: | ||||
| Negative | Reference | - | - | |
| Positive low | -0.08 (0.12) | -0.68 | 0.495 | -0.33 to 0.16 |
| Positive high | -0.53 (0.23) | -2.33 | 0.02 | -0.98 to -0.08 a |
| Parity: | ||||
| 1 | Reference | - | - | |
| 2 | 0.34 (0.10) | 7.29 | < 0.001 | 0.54 to 0.94 |
| 3 | 1.22 (0.11) | 10.7 | < 0.001 | 0.99 to 1.44 |
| 4+ | 0.71 (0.13) | 5.5 | < 0.001 | 0.46 to 0.96 |
| Kidding season: | ||||
| March to April | Reference | - | - | |
| June to July | 0.06 (0.11) | 0.49 | 0.62 | -0.17 to 0.28 |
| September to October | 0.53 (0.12) | 4.52 | < 0.001 | 0.3 to 0.77 |
| November to December | 0.54 (0.12) | 4.57 | < 0.001 | 0.3 to 0.77 |
| Farm: | ||||
| A | Reference | - | - | |
| B | 0.24 (0.10) | 2.34 | 0.02 | 0.04 to 0.44 |
| C | -0.71 (0.11) | -6.72 | < 0.001 | -0.92 to -0.5 |
| Random effect | SD | |||
| Goat id | 0.82 | |||
| Within goat temporal correlation with first order autoregressive structure (AR1): 0.23 | ||||
AIC: 343081.1
aInterpretation: After adjusting for the effect of parity, kidding season, days in milk and farm, daily milk yields from does that were qPCR-positive high were 530 (95% CI 80 to 980) mL less than does that were qPCR negative. The random effect at the goat level accounts for repeated measures and individual animal variability.
SE: standard error.
CI: confidence interval