Table 6.
Results from linear models investigating the association of O. ostertagi, F. hepatica and D. viviparus BTM ELISA results and average annual milk yield per cow (kg) in three regions of Germany. Full models were significantly different from null models containing only an intercept term (North: Df = 13, F = 8.5, p < 0.001; East: Df = 11, F = 20.1, p < 0.001; South: Df = 18, F = 8.8, p < 0.001). Significant p-values are printed in bold. Seropositivity categories are defined as follows: O. ostertagi: +: ODR ≥ 0.5, ++: ODR ≥ 0.8; F. hepatica: +: 30% < S/P ≤ 80%, ++: 80% < S/P < 150%, +++: S/P ≥ 150%; D. viviparus: +: ODR ≥ 0.41.
| North (N = 192) | East (N = 193) a | South (N = 207) b | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Variable | Est. | SE | t | p | Est. | SE | t | p | Est. | SE | t | p |
| Intercept | 6441.89 | 1985.87 | 3.24 | 0.001 | −167.19 | 2605.5 | −0.06 | 0.949 | 9611.54 | 1590.34 | 6.0 | <0.001 |
| O. ostertagi + | −153.97 | 196.78 | −0.78 | 0.435 | −195.30 | 193.75 | −1.01 | 0.315 | −219.67 | 188.72 | −1.16 | 0.246 |
| O. ostertagi ++ | −40.11 | 312.66 | −0.13 | 0.898 | −832.74 | 326.22 | −2.55 | 0.012 | −403.61 | 346.48 | −1.17 | 0.246 |
| F. hepatica + | −1157.71 | 372.17 | −3.11 | 0.002 | 1416.02 | 1106.52 | 1.28 | 0.202 | 132.62 | 469.94 | 0.28 | 0.778 |
| F. hepatica ++ | −1335.25 | 445.64 | −3.00 | 0.003 | - | - | - | - | −273.37 | 316.56 | −0.86 | 0.389 |
| F. hepatica +++ | −1129.20 | 376.19 | −3.00 | 0.003 | - | - | - | - | 985.30 | 355.25 | 2.77 | 0.006 |
| D. viviparus + | 159.61 | 430.40 | 0.37 | 0.711 | 724.11 | 509.20 | 1.42 | 0.157 | - | - | - | - |
| Breed type (DP vs. HD) | −2236.55 | 855.00 | −2.62 | 0.010 | −1576.49 | 785.00 | −2.01 | 0.046 | −1259.64 | 293.53 | −4.29 | <0.001 |
| Breed type (Mix vs. HD) | 721.34 | 861.16 | 0.84 | 0.403 | −1015.21 | 357.5 | −2.84 | 0.005 | −1399.50 | 370.78 | −3.77 | <0.001 |
| Lactation no. | 2723.21 | 1330.63 | 2.05 | 0.042 | 7844.89 | 1847.15 | 4.25 | <0.001 | −289.28 | 1037.87 | −0.28 | 0.781 |
| Lactation no. (squared) | −504.38 | 225.54 | −2.24 | 0.027 | −1458.48 | 328.97 | −4.43 | <0.001 | 52.26 | 166.83 | 0.31 | 0.754 |
| SCC (×1000/mL) | −4.27 | 1.06 | −4.01 | <0.001 | −2.63 | 0.90 | −2.93 | 0.004 | −2.77 | 0.85 | −3.26 | 0.001 |
| No. of animals | 3.92 | 1.71 | 2.29 | 0.023 | 0.59 | 0.23 | 2.50 | 0.013 | 7.95 | 2.57 | 3.10 | 0.002 |
| farm type (ORG vs. CON) | −1522.86 | 522.11 | −2.92 | 0.004 | −2446.93 | 343.01 | −7.13 | <0.001 | −1685.37 | 266.41 | −6.33 | <0.001 |
| farm type (TRA vs. CON) | - | - | - | - | - | - | - | - | −245.64 | 399.71 | −0.62 | 0.540 |
| Breed (DP)/F. hepatica + | - | - | - | - | - | - | - | - | 759.10 | 648.05 | 1.17 | 0.243 |
| Breed (Mix)/F. hepatica + | - | - | - | - | - | - | - | - | 498.60 | 868.11 | 0.57 | 0.566 |
| Breed (DP)/F. hepatica ++ | - | - | - | - | - | - | - | - | −2.10 | 692.58 | −0.00 | 0.998 |
| Breed (Mix)/F. hepatica ++ | - | - | - | - | - | - | - | - | - | - | - | - |
| Breed (DP)/F. hepatica +++ | - | - | - | - | - | - | - | - | 1430.93 | 685.62 | 2.09 | 0.038 |
| Breed (Mix)/F. hepatica +++ | - | - | - | - | - | - | - | - | 2050.29 | 1128.19 | 1.82 | 0.071 |
a Three outliers were excluded, these were the three smallest herds in the northeastern region. b One outlier was excluded, this was the largest herd in the Bavarian dataset. Abbreviations: CON, conventional; Est., estimate; DP, dual-purpose; HD, high-performance dairy; ORG, organic; SCC, somatic cell count; SE, standard error; TRA, in transition from conventional to organic.