THE BEHAVIORAL, ENDOCRINE AND IMMUNE-RESPONSES OF SHEEP TO ISOLATION

Two groups of five sheep (7 months of age) were moved and isolated in pens which did not allow visual and tactile contact with other sheep f or 24 h. They were then moved back to their original pens where visual and tactile contact was possible. After 24 h the procedure was repeat ed seven times for one group (group 8-I) and thirteen times for the ot her group (group 14-I). One group (control) of five sheep remained in pens where visual and tactile contact was possible. When isolated the lambs spent more time standing still in an alert posture, less time ea ting and resting, and vocalized more than control lambs. The heart rat e of the lambs increased when they were moved between pens and during isolation. The plasma concentration of cortisol was significantly incr eased after 1.5 h and 3 h of isolation. The plasma concentration of pr olactin was increased after 1-5 h of isolation. After 3 h of isolation the number of neutrophils in the blood was increased and the numbers of T-lymphocytes (CD2), T-helper-lymphocytes (CD4) and gammadelta-lymp hocytes (T19) were decreased. After 24 h of isolation the lymphocyte b lastogenic response to Con A was lower and the numbers of T-lymphocyte s and T-helper-lymphocytes were still less than those in control lambs . Although there were still behavioural changes when the lambs were is olated for the seventh time, no cortisol, prolactin and leucocyte chan ges were found. These results suggest that stressors similar to isolat ion, which can occur during normal management practice, may elicit sho rt-term leucocyte changes in lambs.