Towards a common conceptual framework and illustrative model for feather pecking in poultry and tail biting in pigs: Connecting science to solutions

Feather pecking (fp) in poultry and tail biting (tb) in pigs are among the most persistent animal-welfareproblems associated with intensive livestock farming. Both problems have been studied and reviewedextensively (e.g. fp: (Rodenburg et al., 2008; Nicol et al., 2013; Rodenburg et al., 2013); tb: (Schrøder-Petersen and Simonsen, 2001; Bracke et al., 2004a; EFSA, 2007b; Taylor et al., 2010; D’Eath et al., 2014;Valros, 2017)). Legislation and policy initiatives have been discouraging the continued performance ofroutine mutilations (beak treatment and tail docking for fp and tb respectively). However, both poultry andpig farmers generally find it difficult to stop mutilations and prevent and/or treat these injurious behavioursin intensive farming systems. Comparing fp and tb may help address these problems. However, few papershave compared the two forms of abnormal behaviour in detail. One notable exception is the fairly recentOpen-Access publication by Brunberg et al. (2016). These authors discussed similarities and differencesbetween fp and tb, and presented a general model which looks somewhat like an envelope. This publicationis written for a scientific audience, and it is not easy to read for farmers and others interested in solving fp/tbsuch as vets, other farm advisors and NGOs. Also the ‘envelope-shaped’ model presented by Brunberg et al.(2016) is not as appealing as we would (ideally) like it to be. It mainly says that by nature both pigs andpoultry are omnivorous generalists that have (had to) become production specialists via genetic selection andrearing in large-scale intensive systems applying a one-size-fits-all principle. According to Brunberg et al.both the physical and social environment (‘where you are’ and ‘who is with you’), together with animal related factors (‘who you are’) determines ‘what you become’ in terms of fp or tb, i.e. a performer(pecker/biter), victim/receiver or a neutral animal. The authors also hypothesise that the gut-microbiotabrainaxis may play a crucial role which should be investigated further. This is in accordance with thecommon view that fp and tb are multifactorial problems associated with the substantial discrepancy betweenthe natural and the commercial environment resulting in a (seriously) deprived foraging (and/or feeding)motivation that eventually leads to fp/tb (and worse, i.e. cannibalism, if not curtailed adequately). It is not entirely clear, however, why the model (figure) in Brunberg et al. (2016) should look like anenvelope. When looking a bit more closely at the figure, the model appears to encompass everything (theanimal, its history and its entire, physical and social, environment). Only upon more careful examination andin particular when reading the text itself do the further ramifications underlying the model become moreclear. Since we feel the text may be rather inaccessible for practical application in problem solving, oneobjective of these blog posts, therefore, is to compare this model to other models, esp. those developed inour own organisation (Wageningen University & Research), in order to see if we can better highlight theavailable knowledge that should be used to (eventually help) solve the problem in practice. To this end wehave also tried to make the information presented by Brunberg et al. (2016) more accessible, and wesupplemented it with our personal expertise on fp/tb. It is important to emphasise, however, that the primaryaim of this publication is to improve on the available conceptual frameworks to facilitate practicalunderstanding of fp and tb so as to support solving the problem in the future. We do not, however, aim topresent a tool box or cook book for solving fp/tb.