Hemsworth, P. H., Barnett, J. L., Hansen, C. 1986. The influence of handling by humans on the behaviour, reproduction and corticosteroids of male and female pigs. Applied Animal Behaviour Science 15, 303-314 .

Animals who are fearful of humans show a marked increase in corticosteroid levels both in the presence and in the absence of people. Unpleasant handling treatment resulted in a chronic stress response, with consequent adverse effects on reproduction.