## 2 Materials and Methods
### Statistics  
All data were processed and prepared for further statistical analysis by using Excel (version 2013, Microsoft Corporation, Redmond, WA, USA). In the second rearing and laying period, flock 7 was excluded from further statistical analysis, owing to a severe infectious disease in the middle of the laying period. For the further analysis, the percentage of birds with plumage damage (triscore \(\leq 10\)) was calculated.  
In both rearing and laying periods, housing and management data's relation to plumage damage was analyzed in two steps, using univariate analysis first. For the rearing periods, the effect or the correlation was analyzed for the following variables:  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Points** & **Plumage Scoring: Pullets** & **Plumage Scoring: Layers** \\ \hline
5 & - & \(\leq\)5 feathers damaged, no nude areas \\
4 & No damage & \(>\)5 feathers damaged, nude areas \(\mathcal{O}\leq 1\) cm \\
3 & Damaged feathers & Nude areas \(\mathcal{O}>1\) cm to \(\leq 5\) cm \\
2 & Single feathers missing & Nude areas \(\mathcal{O}>5\) cm up to \(\leq 75\%\) of the body region \\
1 & Nude areas \(\mathcal{O}>1\) cm & Nude areas \(>\)75\% of the body region \\ \hline \hline \end{tabular}
\end{table}
Table 3: Definitions for individual plumage and integument scoring for pullets and laying hens, modified according to [PERSON] et al. [59] and [PERSON] [60]. \(\mathcal{O}=\) diameter. For the individual plumage and integument scoring, separate body region scores per bird were given for: neck dorsal, back, and wings.  
'mixed flock'; 'housing system'; 'daylight'; 'hybrid line' (LB, LSL, DW, BB);'stocking density' (pullets per square meter of usable area); 'perch length per pullet' (in centimeters); 'feeding trough length per pullet' (in centimeters); 'number of pullets per drinking nipple'; 'flock size'; 'number of pullets per caregiver'; and 'attendance time per 1000 pullets per day' (in minutes). In the second rearing period, additionally, 'litter quality' and 'litter depth' were analyzed.  
For both laying periods, either the effect or the correlation of the following variables, regarding the occurrence of SFP and cannibalistic injuries, were analyzed:'mixed flock'; 'free range'; 'enrichment'; 'daylight'; 'hybrid line' (LB, LSL, DW, BB);'stocking density' (laying hens per square meter of usable area); 'flock size'; 'perch per laying hen' (in centimeters); 'feeding trough length per laying hen' (in centimeters); 'number of laying hens per drinking nipple'; 'number of laying hens per caregiver'; and 'attendance time per 1000 laying hens per day' (in minutes). Additionally, 'litter quality' and 'litter depth' were analyzed for the second laying period, to account for findings in the literature [39; 43; 49].  
For categorial data, a Shapiro-Wilk test was calculated for the mean values of plumage damage percentage, to test for normal distribution. Not all variables were normally distributed; therefore, a Mann-Whitney \(U\) test for independent samples was chosen. The effect ([PERSON]'s \(d\)) was calculated, using the means and standard deviations [63] to describe small, medium, and large effects [64]. For ratio data, [PERSON]'s tau correlation coefficient (\(r\)) was calculated.  
To analyze the influence of management and housing on the occurrence of SFP and cannibalism in all flocks, in both rearing and laying periods, models using multifactorial analysis were calculated. The calculated partial eta-squared explained the percentage of independent variables on the variability of the dependent variables. The corrected partial eta-squared incorporated the number of factors analyzed.  
[PERSON]'s \(V\) and a chi-squared test were used to calculate the relation between plumage damage in the rearing period and plumage damage in the laying period.  
Details for the plumage and integument scoring results for the first rearing and laying period can be found in Lenz [65], and for the second rearing and laying period in Szczepanek [66].