Table 1. Number of cows, average ± standard deviation of anti-F. hepatica antibody levels before treatment and 305-day milk production in the lactation before treatment and distribution of breed, parity and year quarter of treatment in the 2 treatment groups.
| Parameter | Closantel | Placebo |
| N° of cows | 208 | 194 |
| Anti-F. hepatica antibody level (ODR) | 0.36±0.26 | 0.40±0.27 |
| 305-day milk production (kg) | 9,012±1,661 | 9,059±1,742 |
| Breed: | ||
| Holstein Friesian | 45.3 | 43.0 |
| Dutch Friesian | 6.5 | 5.2 |
| Parity (%): | ||
| 1st | 11.2 | 10.5 |
| 2nd | 16.7 | 13.7 |
| ≥3rd | 23.9 | 24.1 |
| Year quarter: | ||
| Jan–Mar | 12.4 | 11.9 |
| Apr–Jun | 5.2 | 4.7 |
| Jul–Sep | 16.9 | 15.7 |
| Oct–Dec | 17.2 | 15.9 |