Coping styles of tethered sows.

Behaviour of 20 non-pregnant primiparous sows was observed from the moment of first tethering till 2 hours thereafter, and after being tethered for 1 and 2 months. After 2 months of tethering the sows could be divided into 2 distinct groups; (1) high stereotypers and (2) low stereotypers. Sows that resisted most at first tethering showed the lowest level of stereotyping after 1 and 2 months of tethering. High resisting sows may experience the uncontrollability of first tethering most drastically and develop a state of helplessness. Low resisting sows may accept tethering easier and adapt by means of developing stereotypies. Low stereotyping sows were more alert after 1 and 2 months of tethering than high stereotyping ones. Heart rate measurements showed that high stereotyping sows had lower mean heart-rates after feeding (when stereotyping is most pronounced) than low stereotyping ones. This difference was already present before tethering when the sows were loose-housed. The results show differences in styles of coping in sows that become more visible during tethering.