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Doctoral thesis, 2019

A tale of tails

Wallgren, Torun


-Pigs in their natural environment spend the majority of their time exploring their surroundings through rooting, sniffing and chewing to find food and resting places. Rooting under commercial conditions is often fully dependent on the provision of rooting material. Lack of rooting opportunity may redirect the exploratory behaviour and cause tail biting, an abnormal behaviour that causes acute, long- and short-term pain. Tail biting is a common issue in modern pig production, reducing health, profitability and animal welfare. To fulfil pigs’ explorative needs, the Council Directive 2008/120/EC states that pigs should have permanent access to a sufficient amount of material, such as straw, to enable proper investigation and manipulation activities.

 However, instead of improving pig environment to reduce tail biting, >90% of pigs in the EU are tail docked despite the prohibition of routine docking. Docked pigs have a less attractive and more sensitive tail tip and are less willing to allow biting. Docking aims at reducing the symptoms of tail biting rather than eliminating the cause. One argument for not increasing exploration through e.g. straw provision is fear of poor hygiene.

 The overall aim of this thesis was to investigate the effect of straw on tail lesions, behaviour and hygiene (Studies I and II) as well as investigating tail position as a method for early detection of tail biting (Study III) in commercial production. Study I showed that 99% of Swedish farmers provide their pigs with straw (mediangrowers: 29 gram/pig/day; medianfinishers: 50 gram/pig/day). The amount of tail biting recorded at the abattoir was on average 1.7%. Study II showed that an increased straw ration decreased presence of tail wounds and initiated more straw-directed behaviour. Straw had little effect on hygiene. Study III showed that tail posture (hanging or curled) at feeding correctly classified 78% of the pigs with tail wounds. Less severe tail damage, e.g. swelling or bite marks, did not affect the tail posture.

 The main conclusions are that increased straw reduces tail damage as well as pen-directed behaviours. Instead, straw increases straw-directed behaviours, while not affecting pig and pen hygiene negatively. Hence, it should be possible to rear pigs with intact tails without the use of tail docking in the EU.


pig, finisher, grower, intact tail, tail lesions, enrichment, tail docking, pen hygiene, pig hygiene, housing environment

Published in

ISBN: 978-91-7760-428-0, eISBN: 978-91-7760-429-7
Publisher: Swedish University of Agricultural Sciences