THE EFFECT OF INDIVIDUAL AND GROUP HOUSING ON BEHAVIOURAL AND PHYSIOLOGICAL RESPONSES RELATED TO THE WELFARE OF PREGNANT PIGS

Abstract The effects of four housing treatments (neck-tethers, stalls, a group indoors and a group in a paddock), imposed at 3–5 weeks after mating, were determined on the behaviour and physiology of 24 pigs. Behaviour observations were made 2–3 days after the treatments began and 4 and 9 weeks later, and physiological measurements were made 18 and 46 days after the treatments began. Pigs in tethers spent less time in active behaviours than all other treatments, and the pigs housed in stalls showed increased amounts of oral—Nasal behaviours such as manipulation of drinkers and licking/biting pen components (7% of observations) compared to all other treatments (3.1–4.8% of observations). The pigs in tethers had highest free corticosteroid levels “at rest” (2.2 ng ml −1 compared to an average of 1.4 ng ml −1 for the other treatments), a disrupted rhythm of corticosteroid levels and, at the second sampling period (9–12 weeks of pregnancy), a lower response to transport; these responses in the tethered pigs were associated with an increase in plasma glucose and a decrease in plasma urea levels. These physiological data indicate a chronic stress response and a significant metabolic cost resulting from housing pigs in tethers. The implications of the results to the welfare of pregnant pigs are discussed.