PhD: Tail-biting in pigs is related to multiple physiological changes

Tail biting in pigs is a phenomenon which has been known since the 19th century. The prevalence of tail biting damage is estimated to be between 3 - 10 % of pigs slaughtered, being somewhat higher in non-docked than tail-docked populations. Being tail bitten causes pain and a state of stress to the victim pigs, as well as general disturbance in pig groups. PhD study shows that tail biting is related to physiological changes in brain, intestines and blood.

New knowledge for resolving the multifactorial mystery of tail biting behaviour is needed. The precise etiology of tail biting behaviour is unknown, although many risk factors have been identified. The most supported theory of tail biting involves lack of opportunities for pigs to fulfil their innate need for exploration and foraging behaviours in modern production environments. Both these behaviours are mainly performed orally. Deficiencies in the nutritional state of the animal can increase the motivation for foraging behaviour.

Results presented in this thesis from the population level study identified environment-, feeding- and management-related risk factors that were similar to those reported in earlier published epidemiological studies of both long-tailed and tail-docked pigs. Interactions between different types of risk factors were depicted. Both the etiologies of tail biting which originates from exploratory and foraging behaviour can be supported by the found risk factors. The similarities between the risk factors for tail biting and gastric ulceration needs more attention in future studies.

Both the biters and their victim pigs had changes in brain neurochemistry associated with the stress. Tail biting pigs had elevated serotonin metabolism in the prefrontal cortex, and tail bitten pigs decreased concentration of several non-essential amino acids in blood, and a higher ratio of metabolites of serotonin and dopamine in the striatum and in the limbic cortex. In addition, in a pen where tail biting was present, also the control pigs were affected, they had reduced intestinal villus height and changes in blood nutrient concentrations that indicate short term malnutrition, possibly resulting from changes in feed intake.

MSc Pälvi Palander will defend her thesis : The Tail biting pig - Nutritional and physiological approaches to understanding the behavior at the University of Helsinki, Faculty of veterinary medicine, 4.11.2016 at 12 hrs.

Place: Seinäjoki University center, Hall 2, Kampusranta 9 B, 60320 Seinäjoki 

Professor Anna Valros (the University of Helsinki, Faculty of veternary medicine) will be serving as a custos and D.Sc. Hans Spoolder (Wageningen University and Research, Netherlands) is an opponent.


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Pälvi Palander