Table 3.
Descriptive statistics of the dependent variables (FP: feather pecking, FD: feather damage), continuous independent variables, and categorical independent variables in the database.
| Variable | N1 | Mean (SD) | SE | Median | Min | Max |
|---|---|---|---|---|---|---|
| Dependent variables | ||||||
| FP (pecks/bird/min) | 110 | 0.03 (0.063) | 0.006 | 0.01 | 0.0 | 0.60 |
| FD (1–4 scale) | 114 | 3.1 (0.75) | 0.07 | 3.3 | 1.4 | 4.0 |
| Continuous independent variables | ||||||
| Age at FP (week) | 126 | 21.6 (11.44) | 1.02 | 23.0 | 1.0 | 53.0 |
| Age at FD (week) | 118 | 40.8 (14.57) | 1.34 | 40.0 | 10.0 | 72.0 |
| Categorical independent variables | ||||||
| Housing type | ||||||
| Cage | 60 (28.6%) | |||||
| Noncage | 150 (71.4%) | |||||
| Beak trimming2 | ||||||
| No | 122 (61.6%) | |||||
| Yes | 74 (37.4%) | |||||
| Both3 | 2 (1.0%) | |||||
| Enrichment | ||||||
| No | 91 (43.3%) | |||||
| Yes | 119 (56.7%) | |||||
| Enrichment period | ||||||
| Laying | 137 (65.2%) | |||||
| Rearing | 73 (34.8%) | |||||
| Feather color | ||||||
| Brown | 76 (36.2%) | |||||
| White | 118 (56.2%) | |||||
| Silver | 8 (3.8%) | |||||
| Combination3 | 8 (3.8%) |
1
N is total number of observations for which information was available. Presented as N (% of observations) for categorical variables.
2
Note that not all studies specified beak trimming status and therefore N does not equal 210 observations.
3
Data were not presented separately for the different categories.