STEREOTYPIES AND CORTISOL SECRETION IN HEIFERS SUBJECTED TO TETHERING

The aims of this study were to assess the effect of tethering on environmentally induced stereotypies and urine cortisol concentration in Swedish Red and White heifers, and to analyse a possible relationship between the performance of stereotypies and cortisol concentration. Three groups of heifers (N = 14) with oral stereotypies, mainly consisting of tongue-rolling, were studied during three consecutive autumns. Recordings of the duration and frequency of stereotypies were made from the second and third day after the heifers had been transferred from pasture and tethered indoors, and for 7 weeks thereafter. The four heifers from the previous year were also subjected to urine collection to determine total 24-h concentration of cortisol during Weeks 1-8 post-tethering. An adrenalcorticoid response test was conducted after 8 weeks of tethering. Exogenous adrenocorticotropic hormone (ACTH) was administered to heifers with, and without, stereotypies. All 14 heifers from the three cohorts showed the same pattern concerning time allocated to stereotypies during the 8 weeks post-tethering. From a zero-level in pasture, they increased the time spent performing stereotypies until Week 4, whereafter the stereotypy level decreased. The heifers all had similar patterns of cortisol concentrations during the observation period. The cortisol concentration was high during the first week after tethering (on average, 84.25 nmol l-1), but from the second week onwards the concentration was decreased. The ACTH test showed no difference in adrenal status between tethered heifers with, or without, stereotypies. There was no indication that individual variation in cortisol level was associated with the performance of stereotypies. This study shows that tethering after a grazing period leads to increased levels of stereotypies and high urine levels of cortisol.