Stereotypies in sows during chronic stress.

In pig husbandry sows are fixed in such a way that they undergo a chronic loss of control over their environment. In these conditions sows develop stereotypies that are associated with a specific activation of brain endorphins. Stereotyping itself reduces some neuroendocrine stress symptoms. During stress at least two coping styles can be distinguished in many mammals and birds. These types are found again in the stressed sows which either maintain a high or a low level of stereotypies. The low stereotyping sows show the strongest signs of uneasiness.