An evaluation of ethological criteria and methods in the assessment of well-being in sows.

The literature on behaviour of sows under different management systems was reviewed to evaluate ethological criteria and methods in the assessment of wellbeing. Daily activity time seems of little value in the assessment of wellbeing when housing systems are compared. It is low in confined sows, especially those that are tethered or otherwise restricted. Lack of exercise, however, has well-documented adverse effects in tethered and restricted sows. A number of well-known responses to conflicts and frustration have been observed in confined sows, but the effect of tethering and restriction varies. These responses include increased aggression, displacement activities, immobility responses, flight reactions and "inhibition of all but one response". Additionally the tethered and restricted sows frequently perform a number of stereotypes and vacuum activities. The effect of potential stressors in tethered sows, such as closeness of other individuals, high environmental temperature, lack of stimulation and thwarting of nestbuilding behaviour during the prefarrowing phase is discussed and evaluated on the basis of ethological parameters. The conflict behaviour, the stereotypes, and the vacuum behaviour seem of significance in the assessment of wellbeing, but more research is needed, especially on the significance of the stereotypes and their physiological correlates.