Positive emotions and environmental enrichment in pigs

We studied behaviours indicating positive affective states when social groups of pigs got access to a limited amount of specific rooting materials twice a day in the weaning period (5 weeks). In the first study, we observed behaviours considered indicative of positive (exploration, play, tail curled, wagging) and negative (aggression, ear or tail biting, tail down) behavioural responses to straw, silage, peat, or a combination of the three different materials in comparison to no added rooting materials (control condition, wood shavings litters present in all pens). In addition, we investigated the effect of rooting material on the activity budget on pigs (performance of variety of positive behaviours). Our results suggest that peat, or peat in combination with long-stemmed straw and silage, were the most effective rooting materials for inducing positive (i.e. increased incidence of positive behaviours), and reducing negative states (i.e. reduced incidence of negative behaviours) in weaned pigs. However, a combination of different rooting materials resulted in the greatest variety of positive behaviours. Straw and silage as single materials were intermediate regarding their stimulatiing properties, and the control groups had the greatest number of negative behaviours and the lowest number of positive behaviours. In conclusion, a combination of Three materials provided two times a day was the most stimulating and resulted in the most positive affective state in weaned pigs. In a second study, we included Felleskjøpets recently developed "miljøfôr" that is meant to stimulate rooting and exploratory behaviour. We included straw, peat and the combination of the three and compared this to the control condition. This time we wanted to assess the effects of the different rooting materials and the combination of the three on behaviour, weight gain, learning ability, fear and ease of handling. The study was based on video analysis of behaviours in the groups as well as experimental tests. We concluded that especially peat as single material and peat in combination with straw and pellets, stimulate positive behaviours. Access to a combination of rooting materials reduced fear of novel objects, fear of unfamiliar humans, and increased collaboration between pigs to open a lid on a box to get access to rooting material. Again, a combination of three rooting materials was most stimulating for the pigs and could thus be recommended as a routine to improve pig welfare. Currently, we are developing an automated digital system for pigs to automatically recognise behavioural indicators of welfare. We started with annotating video images from the first study to determine posture of tail, head and body. The first task was to see if it was possible to identify individuel pigs in a pen. This was followed up by machine learning (computer) to detect the same type of pig`s body parts and postures. The results are promising with more than 90% precision.

Prosjektet har gitt oss innsikt i viktigheten av miljøberikelse til unge griser som velferdsfremmende tiltak. Vi vet litt mer om hva de foretrekker og hvor ofte de bør stimuleres, og har noen nye ideer hvordan vi praktisk kan få dette til. Griser som får torv eller en kombinasjon av flere rotematerialer er mindre fryktsomme og aggressive, viser mer lek og utforskning og har større evne til samarbeid med kullkamerater om å løse en enkel oppgave. De har mer krøll på halen og logrer mer, ja alt i alt viser de alle tegn på en positiv emosjonell tilstand og velferd. Det ligger videre et stort potensial i å undersøke sammenhengen mellom positive emosjonell tilstand og fysisk helse hos griser som blir stimulert på denne måten. På denne måten kan vi også studere mer langsiktige konsekvenser. Er konsekvensene også mindre sykdom og lavere veterinærutgifter? Det er i alle fall uomtvistelig klart at det gir grisene en langt bedre livskvalitet.

We hypothesize that behavioural indicators of positive emotions can be induced by satisfying basic behavioural needs in both weaned pigs: the need to explore and root in a social setting. We also hypothesize that positive stimulation will reduce fear and frustration, enhance learning capacity,and improve physical health status. The following, two sources of pleasure previously described by Cabanac (2002) will be used to induce positive affect in the present study: desire/fulfilment of a need and pleasure in solving cognitive challenges. In pigs, the approach will be to first provide access to a preferred rooting stimulus together with social companions and then later to use a cognitive task rewarded with this preferred rooting stimulant. In the first phase of the project when asessing positive behavioural indicators, this will be studied in our experimental, university herd. Pigs will be given free access to different rooting stimulants, followed by an experimental situation where they have to work for the stimulus that initiated the largest number of positive behaviours, included rooting, exploration and play behaviour. Play behaviour will be studied in more detail. The next phase when we are investigating effects of the most preferred rooting stimulant, will be conducted in a commercial herd. The design will be to compare the behavioural indicators of positively stimulated young, weaned pigs vs. control groups (both groups being clinically healthy). In summary, we first want to study the effects on two different rooting stimulants and to compare this to a control group in an experimental setting. In the next step , we will develop a practical device, a dispenser from which the pigs can get access to the preferred rooting stimulant and work for access to the substrate. Finally this device will be tested in commercial pig farms to become a commercial product.