Urinary cortisol as an additional tool to assess the welfare of pregnant sows kept in two types of housing

The use of urinary cortisol (UC) as an additional tool to evaluate sows welfare was as- sessed in two experiments. In a preliminary methodological experiment, the kinetics of cortisol ex- cretion in urine was studied during an Adreno Cortico Trophic Hormone (ACTH) challenge test in 10 pregnant sows. In a second experiment, 96 primiparous sows of an experimental unit were as- signed to two different housing systems: 48 animals were housed in individual pens (IP) and 48 ani- mals in collective pens (CP) with 6 animals per pen. UC was measured at the beginning and at the end of pregnancy and compared with other welfare indicators such as behaviour or skin damage. In both experiments, UC was measured using a high pressure liquid chromatography assay. In experiment 1, UC was constant on the day before injection of ACTH, with no variations related to circadian rhythm. It began to rise 2 h after the injection, peaked between 2 t o5ha fter then returned to the basalconcen- tration on the day after the injection. In experiment 2, UC concentrations were not different between CP- and IP-housed sows but they were higher in sows exhibiting the less stereotypies in comparison with sows exhibiting the most stereotypies. The results of this study suggest that UC is a good indica- tor of acute stress, more convenient than plasma cortisol measurement since it is a non-invasive method avoiding restraint or catheterisation of sows. They also suggest that UC could also give addi- tional information on the assessment of chronic stress and improve the evaluation of animal welfare if used in conjunction with other welfare indicators. pig / urinary cortisol / group housing / stress / welfare