Table 1.
Characteristics of herds included in the study given as the median, interquartile range and range or as the count and percentage of the entire group
| Entire study population (n = 598) | Province | p | ||
|---|---|---|---|---|
| north-eastern (Podlaskie) (n = 394) | central (Łódzkie) (n = 204) | |||
| Herd size | 21, 15–30 (10–109) | 24, 17–32 (10–109) | 18, 14–25 (10–100) | < 0.001 |
| Average milk yield | 5500, 460–6400 (1700–10,200) | 5500, 4500–6400 (1700–10,200) | 5200, 4800–6150 (3000–9360) | 0.982 |
| Grazing policy | < 0.001 | |||
| No grazing | 264 (44.2%) | 118 (30.0%) | 146 (71.6%) | |
| 6 h a day | 66 (11.0%) | 46 (11.7%) | 20 (9.8%) | |
| 12 h a day | 179 (29.9%) | 156 (39.6%) | 23 (11.3%) | |
| 24 h a day | 89 (14.9%) | 74 (18.7%) | 15 (7.3%) | |
| Length of grazing period in months (only grazed herds) | 5 (1–8) | 5 (1–8) | 5 (1–7) | 0.023 |
| Main roughage | < 0.001 | |||
| Haylage | 311 (52.0%) | 273 (69.3%) | 38 (18.6%) | |
| Corn silage | 263 (44.0%) | 103 (26.1%) | 160 (78.4%) | |
| Hay | 24 (4.0%) | 18 (4.6%) | 6 (3.0%) | |
| Proportion of grazing grass in diet | < 0.001 | |||
| No grazing grass | 203 (33.9%) | 90 (22.8%) | 113 (55.4%) | |
| Grazing grass < 50% of all roughage | 204 (34.1%) | 135 (34.3%) | 69 (33.1%) | |
| Grazing grass > 50% of all roughage | 191 (32.0%) | 169 (42.9%) | 22 (11.5%) | |