## 1 Introduction
Provision of litter and sufficiently high perches were found to be preventative for SFP in a review [30]. Housing and management factors play an important role during the laying period as well [28; 30; 38]. A field study on 107 laying-hen flocks in Europe found that lower dietary protein content, and no daily access to free range, had an influence on feather damage in brown hens [39]. This finding is in line with other studies [1; 30; 33; 40; 41; 42]: laying hens in free-range housing had less plumage damage than birds kept in avariies [30; 43], especially if the extra space was used extensively by the laying hens [1; 44]. In a French field study of 80 free-range flocks, feather cover was associated with use of the outdoor run, lighting program, genotype, farm location, and date of housing construction [45]. In a Bavarian survey, the prevalence for SFP was 18.5% (293 flocks on 147 farms), and was related to the farming system, the presence of roosters, the locking of laying hens into the ariary, not allowing access to the entire litter space after housing, and the nervous or chasing behavior of laying hens [46]. Larger flocks are associated with more SFP [1; 5; 16]. A lower drinking place per hen ratio might predict SFP during the laying period [47], but this finding may have been an indirect effect [30]. Another study found that a high percentage of SFP was observed on perches [48]. A lack of perches, in combination with plastic grids on the ariary tiers, increased the percentage of hens with missing feathers [47]. Perches installed well above head height of the birds helped to improve their plumage condition [30; 47]. There is some evidence that litter [49] and environmental enrichment, such as pecking stones, reduce SFP, but this effect may also be due to other management factors [50]. Enrichment such as pecking stones and alfalfa bales may have diverging effects between strains, and future practical recommendations for laying-hen husbandry should be strain-specific [51]. A meta-analysis confirmed the modest effectiveness of environmental enrichment in reducing SFP and, subsequently, plumage damage, but suggested that other management strategies must be implemented to reduce SFP [52]. Feather pecking, however, is a multifactorial problem, and different studies often identify contradictory findings [52; 53]. An individual risk analysis is therefore recommended [43; 54; 55], including feeding [54], which might help to forecast SFP during the laying period [55]. Management-based measures have the potential to improve hen welfare regarding injurious pecking [29; 43], and good compliance with recommendations may prevent SFP [29; 42; 56]. This study was conducted to identify housing and management factors in the occurrence of feather pecking in non-beak-trimmed laying hens on commercial farms with avaries. Although beak trimming may reduce the extent of plumage damage, it does not prevent feather pecking and cannibalism [35]. This practice has been banned or has ceased voluntarily in several European countries, including Austria, Denmark, Finland, Germany, and Norway [28; 56; 57]. Therefore, an important aim of this study was to investigate the possible risk factors of SFP in non-beak-trimmed pullets and laying hens.