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Poor health is associated with an increased risk of tail biting outbreaks in pigs. We propose that this is because illness changes social dynamics either by changing the behaviour of the sick pig towards its penmates, the behaviour of the healthy penmates towards the sick pig, or both. We tested the effect of immune stimulation (lipopolysaccharide (LPS) injection: O111:B4; 1.5 mu g kg(-1) IV) on social behaviour in gilts housed in triplets in a cross-over experiment. Each pen was subjected to the control treatment (all three pigs injected with saline) and then LPS treatment (one pig injected with LPS, two injected with saline), or vice versa. LPS injected pigs had a shift in social motivation and performed more tail- and ear- directed behaviour than saline pigs two days after injection. They seemed to fit the description of 'sick and grumpy'. This change was seen about 40 h after the signs of acute illness dissipated and was not accompanied by a similar increase in activity. We discuss possible mechanisms for this behavioural change in light of changes in neurotransmitter levels at three days after LPS injection described in a previous experiment.

Tail biting is detrimental to animal welfare and has negative consequences for producer economy. Poor health is one of the risk factors for tail biting. The first aim of this study was therefore to test for links between health status and behavior related to tail biting at the individual level. The second aim of this study was to test whether variation in cytokines was related to variation in social behavior. These small molecules produced upon immune activation are known to influence behavior both in the direction of withdrawal and increased aggression. This could potentially increase non-functional social behavior and thereby the risk of a tail biting outbreak. To investigate this, we collected behavioral data, health data, feeding data and blood samples from undocked boars at a test station farm in Norway. We compared groups with three different diagnoses: osteochondrosis diagnosed by computer tomography scanning (OCSAN), osteochondrosis diagnosed by clinical examination (OCCLIN) and respiratory tract disease (RESP), with healthy controls (CTR). We tested whether the diagnoses were associated with feeding and growth, social behavior and cytokine levels. We then tested whether there were correlations between cytokine levels and social behavior. We also provide raw data on cytokine levels in the extended sample (N = 305) as there are few publications on cytokine levels measured in pigs living under commercial conditions. OCCLIN pigs visited the feeder less, and fed longer compared to CTR pigs. Pigs diagnosed with RESP showed a large drop in growth the first week after filming, which corresponds to the week they were likely to have been diagnosed with illness, and a tendency to compensatory increase in the week after that. Social behavior differed between experimental groups with OCSCAN pigs receiving more social behavior (both aggressive and non aggressive) compared to CTR, and RESP pigs tending to perform more ear- and tail-biting than controls. There were no differences in absolute levels of cytokines between categories. However IL1-ra and IL-12 showed correlations with several behaviors that have been shown by others to be associated with current or future tail biting activity. To our knowledge, this is the first published study indicating a role for illness in non-functional social behavior in pigs and the first showing a correlation between cytokine levels and social behavior.

We compared the effects of aversive and gentle handling in late pregnant ewes on fearfulness, heart rate variability and spatial learning in lambs. Twenty-four Norwegian-Dala ewes were studied. Ewes were subjected to gentle (i.e. soft talking and calm behavior) or aversive handling (i.e. swift movements and shouting) for 10 min twice a day during the last five weeks of pregnancy. Lambs from aversively (AVS) or gently (GEN) treated ewes were tested at 4 weeks of age. Lamb behavior was recorded during a) a human approach test, composed of 4 min of isolation and 4 min of exposure to an unfamiliar human, b) an umbrella startle test followed by 5-min recording, and c) two repetitions of a maze test. In addition, heart rate variability was recorded telemetrically before and after the human and startle tests. The baseline heart rate variability measures suggested a lower influence of vagal stimulation in AVS lambs. In the human approach test, AVS lambs vocalized and explored the environment less, and were slower to approach the human. They also tended to have higher flight distances during the startle test than the GEN lambs. The prenatal treatment had no significant effect in the maze test. In conclusion, we showed that aversive handling of pregnant ewes increased fearfulness and reduced vagal tone in their progeny compared to GEN lambs. These effects can have consequences for how lambs cope with rearing conditions.