Cognitive Enrichment in Piglet Rearing: An Approach to Enhance Animal Welfare and to Reduce Aggressive Behaviour

It is known that pigs raised in enriched environments express less aggressive behaviour. For this reason, a new method of cognitive environmental enrichment was experimented at the University of Veterinary Medicine Hannover, Germany. In the first phase, 78 suckling piglets were trained to learn the link between a sound given by an electronic feeder and a feed reward in the form of chocolate candies during a period of 8 days. In the second phase, the same piglets were used in resident-intruder tests to verify the potential of the feeding system to interrupt aggressive behaviour. The analysis of all training rounds revealed that piglets learned the commands during 8 days of training and the interest of the piglets increased within training days ( ). In the resident-intruder test, 79.5% of aggressive interactions were broken by feeder activation. In interactions where either the aggressor or the receiver reacted, a high number of fights were stopped (96.7% versus 93.1%) indicating that it was not relevant if the aggressor or the receiver responded to the feeder activation. We conclude that the electronic feeding system has the potential to be used as cognitive enrichment for piglets, being suitable for reducing aggressive behaviour in resident-intruder situations. 1. Introduction In conventional pig production, pigs are usually kept without litter on slatted or at least partially slatted floors. These housing systems providing hygienic and economic benefits are often characterized by a barren environment with scant opportunities for playing or exploring and thus often not fulfilling natural behavioural needs of pigs. Furthermore, group compositions may change for several times in pig’s life, and the social structure is disrupted. This procedure usually happens for the first time when piglets are weaned, a very stressful process, which can be accompanied by reduced well-being and health problems [1, 2]. After separating from the sow, unacquainted piglets of similar weight from different litters are mixed, and naturally they will fight to establish a novel social hierarchy. In order to avoid or reduce aggressive actions after weaning and mixing, several measures were already tried, such as odour masking agents, sedatives, regrouping pigs in darkness, or equipping the pen with a hiding place [3–8]. Most of these methods led only to a postponement of aggressive behaviour after mixing, without reducing it significantly. However, it was shown that environmental enrichment has the potential to reduce aggressive behaviour in groups of pigs and to avoid behavioural