Plasma Cortisol Concentrations after CIDR Insertion in Beef Cows

Contents The objective of this study was to show plasma cortisol concentration after treatment with controlled internal drug release (CIDR) in non-suckling beef cows. On day 9 after oestrus, two cows were inserted with CIDR into the vagina for 24 h and the other two cows were treated as a control group. Four days later, the two control cows were treated with CIDR and the other two CIDR-treated cows were used as controls. Cortisol concentrations were determined by ELISA in plasma samples collected before, during and after insertion of CIDR. There was a significant increase in plasma cortisol concentrations (p < 0.01) after insertion of CIDR. Mean (+/- SEM) plasma cortisol concentrations increased from 1.3 +/- 0.4 to a peak of 8.8 +/- 1.1 ng/ml at 5 h and then decreased to basal concentrations at 7 h after insertion of the device. In conclusion, the insertion of intra-vaginal device causes an increase in plasma cortisol concentrations in beef cows, although the pathophysiological significance of the elevation of cortisol is not known.