STRESS PHYSIOLOGICAL, HEMATOLOGICAL AND CLINICAL-CHEMICAL STATUS OF FARM MINK PLACED IN GROUPS OR SINGLY

The effect of social environment on the number of eosinophil leucocytes, total plasma cortisol, and the ratio between per cent occurrence of heterophil leucocytes and lymphocytes was measured on 168 farm mink. Furthermore, haematological and clinical-chemical variables, the frequences of bite damages, and weight of body and organs at pelting were included in the investigation. The mink kits were placed either individually or in groups consisting of 3 males and 3 females. Differences in social environment had no effect on the number of eosinophil leucocytes, on the ratio between heterophil leucocytes and lymphocytes, nor on the haematological variables. For females in groups, the concentration of cortisol increased in comparison with females kept individually which shows that females in groups have a higher social stress level than females kept individually. Generally, females are more sensitive to stress than males measured by the concentration of cortisol. The activity of the enzymes ASAT and CK and the frequency of bite damages were higher for females in groups than for females kept individually. These results may indicate a higher level of social stress.