Table 3 Overview of the explanatory variables (n = 12) included in the observational study
Population conditions | Explanatory variables Quantitative data = Q Qualitative data = q; q1 nominal and q2 dichotomised | Description |
|---|---|---|
Individual level | Age when grouped (Q) | The decisive age for when calves are housed with other calves for the first time (days) |
Sex (q2) | Whether calves were heifer calves (h) or bull calves (b) | |
Sickness (q2) | Whether any calf was sick or had been treated after birth (yes or no) | |
Space per calf (Q) | The space in the pen per calf (m2) | |
Age when filmed (Q) | The individual age of each calf in every calf-group (days) | |
Group level | Indoor- or outdoor rearing (q2) | If calves were placed indoors (i) or outdoors (o) |
Group size (Q) | The number of calves grouped together (number) | |
Regrouping (q2) | Whether calves had been removed or released from the groups (yes or no) | |
Conventional / organic farm (q2) | If the calf-group came from an organic farm (o) or a conventional farm (c) | |
Age difference in group (Q) | The calculated age difference between the youngest and oldest calves in the group (days) | |
Milk allocation method (q1) | What type of feeding system the calves get their milk allocated in: bowl, trough, robot, or drinker buckets with teat | |
Accessibility to dry teats (q2) | Whether calves had dry teats in their pen (yes or no) |