Effect of straw on behaviour, lesions and pen hygiene in undocked pigs

Implication and impact of straw provision on behaviour, lesions and pen hygiene on commercial farms rearing undocked pigs. By Torun Wallgren, Anne Larsen, Nils Lundeheim, Rebecka Westin, Stefan Gunnarsson, 2018. Appl. Anim. Behav. Sci. In press.


Pigs that received more straw had more straw directed behaviour.•

Pigs that received more straw showed less pen directed behaviour.•

Increased straw ration decreased the amount of damaged tails in finishing pigs.•

Increased straw provision did not affect pen hygiene.


According to the European Union Council Directive 2008/120EC, measures to minimise the risk for tail biting shall be taken before practicing tail docking, e.g. provision of manipulable material. Still,>90% of the pigs within EU are tail docked. Thus, management routines for providing manipulable material in commercial pig production are needed. The aim of this study was to investigate how an increase from normal straw ration influence pig behaviour, occurrence of tail- and ear lesions and impact on pen hygiene.
The experiment was conducted on five Swedish commercial farms; one grower and four farrow-to-finish farms. One batch per farm was studied, following pigs throughout the grower or finishing pig period. Both age groups were examined in two of the farrow-to-finish farms and only finishers in the other two, studying three grower and four finisher batches in total. The pens in a batch were divided into Control (C) and Extra Straw (ES). Pens in C were provided with the farm normal daily straw ratio, while pigs in ES got a doubled C-ration. The pigs in eight focus pens per Treatment were scored for lesions on ears and tails every two weeks. In connection with lesion scoring, behaviour observation was conducted in active pigs during one hour (4 min scan sampling) in the focus pens. All pigs in the batch were examined for tail- and ear lesions during the first and last week of the experiment.
Both growers and finishers spent most of their active time manipulating straw. ES-pigs showed more straw-directed and less pen-directed behaviour in both age groups compared to C-pigs. Behaviour was also affected by farm and age revealing that the impact of an increased straw ration differed between farms and pig age. The increased straw ration did not affect the pen cleanliness, showing that it was practically feasible to increase the straw rations on all participating farms.
The prevalence of tail damages increased with age, and more severe damages was found in C compared to ES. Severe tail and ear lesions were found in ~0.6 and 0.07% of the growers and ~2.2 and 0.75% of the finishers, C- and ES pigs respectively. Approximately 50% of the finishing pigs had tail damages at the end of the study, but the majority of lesions were less than 5 mm long and might not have been detected without close clinical examination.