Differences between feather pecking and non-feather pecking laying hen flocks regarding their compliance with recommendations for the prevention of feather pecking – A matched concurrent case-control design
Introduction
Egg production systems in Europe are undergoing dynamic changes. One driving force is an increasing concern of consumers, legislators and producers with respect to laying hen welfare (Pettersson et al., 2016). In a number of EU countries beak trimming/treating is or will be banned by legal provisions (Sweden, Norway, Finland, UK and the Netherlands), voluntary agreements (Germany) or label guidelines (Austria). However, feather pecking (FP) is still a problem in all housing systems (e.g. Kjaer and Bessei, 2013; Nicol et al., 2013). Reported percentages of affected flocks at the end of lay range from 60% (de Haas et al., 2014: flocks with more than 10% of hens with moderate or severe feather damage in one body region) to 86% (Lambton et al., 2010: flocks in which severe FP was observed).
Severe feather pecking leading to feather loss can result in economic losses as a result of increased food consumption in defeathered birds (Leeson and Morrison, 1978; Tullett et al., 1980) and increased mortality (El-Lethey et al., 2000; Fossum et al., 2009; Heerkens et al., 2015) as well as in reduced animal welfare since FP is painful (Gentle and Hunter, 1990) and hens with feather damage are more susceptible to cannibalistic pecking (Green et al., 2000). A large number of studies have tried to identify risk factors for the occurrence of this undesirable behaviour (reviews by Nicol et al., 2013; Jung and Knierim, 2018). In brief, FP is influenced by the interaction between numerous environmental and genetic factors which mainly affect foraging behaviour and the ability to cope with stress (Rodenburg et al., 2013). Jung and Knierim (2018) listed 32 risk factors during the laying period whose significance were supported by epidemiological or experimental study results with at most one contradictory result. An additional 21 factors had heterogeneous effects in the laying period or they were not confirmed yet, and nine potential preventive factors proposed in practice recommendations have not been studied yet.
At the same time, for multifactorially caused problems, the number of risk factors on a farm may be at least as important as the presence of specific single risks. Support for this idea can be found in the results of Lambton et al. (2013) that farms employing more recommended management strategies had lower FP problems. Similarly, we assume that farmers have higher chances of maintaining a ‘non-FP-flock’ when they comply with a greater number of recommendations how to prevent feather pecking.
To analyse which potential set of variables may be decisive for a flock to become case or control we used a logistic regression. At the same time, we expected that the prevention of feather pecking not only depends on certain factors, but also quantitatively on the extent of compliance with recommendations.
Section snippets
Description of data used
Data from three cross-sectional studies on laying hens in non-cage systems recorded in the years 2004–2014 were available (Table 1). In all studies, flocks were visited when hens were between 30 and 78 weeks of age (Table 1). Management data were collected by interviews using questionnaires. This included general farm information (e.g. number of hen places), flock information (e.g. age at placement, hybrid), data on vaccinations and medical treatments, feeding (e.g. composition, phases),
Results
Plumage damage (score 2 or 1 in the HH and AP project or score 2 or 3 in the MS project) was found on average in 53% of individual birds from case flocks and in 0.5% of hens from control flocks. The study flocks are described with respect to the different independent variables in Table 3, Table 4.
In total, 18 of the original 32 variables passed the pre-selection procedure (Table 3, Table 4) and were presented to forward logistic regression analysis. The resulting significant model (χ2(4, n=137)
Discussion
This study used data from three cross-sectional studies to examine risk factors for the development of FP. The three included studies focused on the main challenges for laying hen farms regarding disease and animal welfare, one aspect being the problem of FP. The 165 included flocks were convenience samples that, however, reflected a wide and well distributed diversity of major conventional and organic non-cage egg production conditions in some European countries, while excluding frequently
Conclusion
The provision of dry litter in a covered veranda and lower stocking density in the hen house were identified as preventive measures against FP. Wooden perches were found to have a preventive effect on FP too, but it is not clear if this was rather due to indirect system related effects or the actual wooden perches. An unexpected negative impact of more drinking places needs further investigation. Our results showed that the chance to maintain a non-FP flock increases, the more recommendations
Declaration of Competing Interest
None.
Acknowledgement
Lisa Jung was financed by the doctoral program ‘Animal welfare in Intensive Livestock Production Systems’; the authors thank the Lower Saxony Ministry for Science and Culture.
Furthermore, the availability of data form the following projects is gratefully acknowledged:
‘Healthy Hens’ (financed by CORE Organic II Funding Bodies, being partners of the FP7 ERA-Net project, CORE Organic II, Coordination of European Transnational Research in Organic Food and Farming systems, project no. 249667),
References (42)
- et al.
Farm level factors associated with feather pecking in organic laying hens
Livest. Prod. Sci.
(2003) Feather-pecking in poultry: its relation with ground-pecking
Appl. Anim. Behav. Sci.
(1986)The effect of a sudden change in floor type on pecking behaviour in chicks
Appl. Anim. Behav. Sci.
(1989)- et al.
Effects of floor type during rearing and of beak trimming on ground pecking and feather pecking in laying hens
Appl. Anim. Behav. Sci.
(1989) - et al.
Predicting feather damage in laying hens during the laying period. Is it the past or is it the present?
Appl. Anim. Behav. Sci.
(2014) - et al.
The effect of dark brooders on feather pecking on commercial farms
Appl. Anim. Behav. Sci.
(2012) - et al.
The effect of rearing environment on feather pecking in young and adult laying hens
Appl. Anim. Behav. Sci.
(2013) - et al.
Specific characteristics of the aviary housing system affect plumage condition, mortality and production in laying hens
Poult. Sci.
(2015) - et al.
The prevalence of feather pecking and development in commercial flocks of laying hens
Appl. Anim. Behav. Sci.
(2001) - et al.
Review of rearing-related factors affecting the welfare of laying hens
Poult. Sci.
(2015)