88 Motivation and environment interactions in the development of oral stereotypies in pigs A.B. Lawrence a, E.M.C. Terlouw b aGenetics and Behavioural Sciences Department, SAC Edinburgh, West Mains Road, Edinburgh EH9 3JG, UK b L N.R.A., Institut de Recherches sur la Viande, Centre de Clermont-Ferrand-Theix, 63122 Saint Genbs Champanelle, France Abstract Considerable attention has been paid to the function of apparently 'disturbed' behaviours, such as stereotypies. In contrast, this paper concentrates on the behavioural mecha- nisms underlying the development and continued performance of oral stereotypies in pigs. Stereotypies have been defined as behaviours that are invariant, persistent in their performance and without an obvious function. These characteristics suggest that stereotypies depend on some form of underlying behavioural activation. Such activation can be induced pharmacologically with the dopamine agonist apomorphine, which causes repeti- tive and prolonged locomotory and oral activities. Under farm conditions, one source of activation seems to be high levels of specific motivations such as feeding. In pregnant sows, restricting food levels increases levels of stereotypy, and does so more reliably and to a greater extent than physical restraint. This suggests that oral stereotypies in sows are in part an expression of foraging behaviour. However, we would not expect food-seeking to be sustained in the absence of reward: perhaps arousal, induced by the too brief meal, stimulates continuing activity at a time when foraging has the highest motivational prior- ity. It also seems that the environment strongly constrains the form of compulsive behaviour: by dramatically limiting the performable repertoire, behaviour is channelled into a few simple elements. Channelling would result in repeated stimulation of a sub-set of neural elements controlling behaviour, perhaps sensitizing them. As a result, their ease of activation and, hence, their persistence and tendency to generalize would be increased. This analysis suggests that stereotypies can be reduced either by lowering foraging motivation, or by allowing for the expression of complex foraging behaviour thereby preventing channelling and sensitization.

Motivation and environment interactions in the development of oral stereotypies in pigs

Download PDF Report

Upload
ab-lawrence
View
214
Download
0

Embed Size (px)

Citation preview

Motivation and environment interactions in the development of oral stereotypies in pigs

A.B. L a w r e n c e a, E . M . C . T e r l o u w b

aGenetics and Behavioural Sciences Department, SAC Edinburgh, West Mains Road, Edinburgh EH9 3JG, UK

b L N.R.A., Institut de Recherches sur la Viande, Centre de Clermont-Ferrand-Theix, 63122 Saint Genbs Champanelle, France

Abstract

Considerable attention has been paid to the function of apparently 'disturbed' behaviours, such as stereotypies. In contrast, this paper concentrates on the behavioural mecha- nisms underlying the development and continued performance of oral stereotypies in pigs. Stereotypies have been defined as behaviours that are invariant, persistent in their performance and without an obvious function. These characteristics suggest that stereotypies depend on some form of underlying behavioural activation. Such activation can be induced pharmacologically with the dopamine agonist apomorphine, which causes repeti- tive and prolonged locomotory and oral activities. Under farm conditions, one source of activation seems to be high levels of specific motivations such as feeding. In pregnant sows, restricting food levels increases levels of stereotypy, and does so more reliably and to a greater extent than physical restraint. This suggests that oral stereotypies in sows are in part an expression of foraging behaviour. However, we would not expect food-seeking to be sustained in the absence of reward: perhaps arousal, induced by the too brief meal, stimulates continuing activity at a time when foraging has the highest motivational prior- ity. It also seems that the environment strongly constrains the form of compulsive behaviour: by dramatically limiting the performable repertoire, behaviour is channelled into a few simple elements. Channelling would result in repeated stimulation of a sub-set of neural elements controlling behaviour, perhaps sensitizing them. As a result, their ease of activation and, hence, their persistence and tendency to generalize would be increased. This analysis suggests that stereotypies can be reduced either by lowering foraging motivation, or by allowing for the expression of complex foraging behaviour thereby preventing channelling and sensitization.