Behavioral and pituitary adrenal-axis responses of dairy cows to social isolation and deprivation of lying down.

The behavior and plasma concentrations of ACTH and cortisol were studied in 30 Friesian cows kept in tie stalls and assigned to three treatments: control (C), deprivation of lying down from 0900 to 1600 and 2200 to 0500 (D), and social isolation (I). Behavior of the cows was observed before and after 4 and 8 wk of treatment. The D- and I-cows showed increased frequency of transitions between different behavioral activities (P < .05). In D- and I-cows the frequency of grooming (P < .01) and idling (P < .001), and the amount of leaning (P < .001) increased. In D-cows the frequency of eating was also increased. The behavior and cortisol response to two novel arena tests performed on two consecutive days after 22 d of treatment suggests that social isolation and deprivation of lying change cows' reactions to a novel environment. After 23 d of treatment, concentrations of ACTH and cortisol were measured during 7.5 h. On d 24, cortisol concentrations were determined at time -.5, 0, .5, 1, 2, 3, 4, and 5 h after i.v. administration of ACTH. Cortisol concentrations did not differ among treatment groups in the baseline series and after ACTH administration. In D-cows, ACTH concentration was increased in part of the baseline series (P < .05). The results suggest that the socially isolated cows were frustrated or tried to compensate for a lack of stimulation and that repeated deprivation of lying down is aversive to cows.