EU Council Directive (2008/120/EC) prohibits the routine practice of tail docking to
control tail biting in pigs, yet most pigs in Europe are still tail-docked. This is
primarily due to a lack of effective solutions with the least economic impact for the
producers, especially in fully-slatted systems. This PhD project aimed to find
strategies to manage tail biting in pigs housed on fully-slatted floors, using
enrichment and dietary strategies.
The first two experiments started with identifying suitable materials as enrichment
for docked pigs housed in fully-slatted system. Pigs’ enrichment use was compared
between four different wood types; beech (Fagus sylvatica), larch (Larix decidua),
spruce (Picea sitchensis) and Scots pine (Pinus sylvestris L.), and also between wood
types (beech, larch, spruce) and a rubber floor toy. Pigs were consistently observed
interacting with the spruce more frequently than the other wood types in the two
experiments, and the rubber floor toy also generated a similar amount of
interaction from pigs as the spruce post. No carcass damage was found which could
be directly related to using dried wood sourced from a commercial sawmill.
The next experiment used a single enrichment item and different fibre levels in the
diet to rear undocked pigs. In a 2×2×2 design, the pigs had either: A) a standard
(weaner 3.7% finisher 5.9%) or high fibre (weaner 5.3% finisher 11.6%) diet; B) a
spruce post or a rubber floor toy as enrichment in the weaner stage; C) the
same/alternated enrichment given in the finisher stage. During this experiment a
high level of tail biting was recorded (n=26 tail biting outbreaks), and a substantial
number of pigs were removed temporarily or permanently from their home pens
due to tail biting. Pigs fed with a high fibre diet had worse tail damage score and
performed more tail biting. Pigs which had the floor toy in the weaner stage and
wood in the finisher stage had slightly lower tail lesion scores. Pigs receiving the
floor toy interacted with the enrichment more frequently overall. This study
showed that higher dietary fibre in a relatively barren environment did not help
reduce tail biting or tail lesions Moreover, a single enrichment item, which was
preferred by pigs in the previous studies, was not enough in a group of 14 pigs to
control tail biting, and thus the quantity of enrichment may be important factor to
consider.
In the final experiment, a 2 × 3 design was used to further investigate the effect of
A) an enriched/barren environment during farrowing and B) three enrichment
management strategies post-weaning, based on the frequency of replenishment
(“Low”: on Monday/Wednesday/Friday; “Medium”: once daily; “High”: ad libitum).
All pens received the same enrichment (8 items/12 pigs, including an elevated rack
supplied with fresh-cut grass). The average daily gain in the finishing stage was
slightly higher in “High” than “Low” pigs. “Low” pigs also performed more damaging
behaviours (tail/ear biting, belly-nosing, mounting, other biting and aggressive
behaviours) than “High” and “Medium” pigs. No difference in lesion scores was
found between treatments. Although sporadic tail biting outbreaks occurred (n=14,
halved compared to the previous trial), they usually resolved within 2 weeks, and all
but one tail-injured pig were successfully reintroduced back to their home pens
after removals. Thus, this study concluded that by employing appropriate
enrichment management strategies, tail biting can be kept at a level without a
negative impact on the production cost in undocked pigs housed in a fully-slatted
system
