Stereotypic behavior, adrenocortical function, and open field behavior of individually confined gestating sows

The adrenocortical response and open field behavior of a random sample of 37 individually confined gestating sows in different parities were tested around day 85 of pregnancy. The sows were classified as stereotyped [S] and nonstereotyped [N] based on 8-h individual behavioral observations during daytime. Behavioral analysis from time-lapse video recordings included percentage of time spent standing and sitting, as well as the duration spent performing elements of stereotyped actions. Blood samples were drawn for cortisol analysis by suborbital sinus puncture before and after adrenocortical stimulation with 200 IU ACTH. Locomotor activity in an open field, isolated visually and auditorily from other sows, was also studied. Seventeen sows exhibited stereotyped behavior for 54.9 +/- 4.8% of the 8-h observation period during daytime. The total time the sows spent standing and sitting was positively correlated with age and was significantly higher for [S] sows than for [N] sows. Sows in the [S] group exhibited a higher adrenocortical response to ACTH stimulation than [N] sows. Mean locomotor scores in the open field were higher for [S] than for [N] sows but these did not correlate with the physical activity and adrenocortical function in the home crate. Our results provide no evidence that the performance of stereotypies constitutes a mechanism that helps sows to cope in an environment of low complexity.