This study was carried out to investigate the effectiveness of active biotelemetry to monitor stress response, and the effects of acute stressor (raising a hind foot of a standing animal) on body temperature (BT) and heart rate (HR) in comparison heifer group (n=4) with cow group (n=3). Both parameters were recorded by active telemetry. Cortisol assay was used to compare the result of active biotelemetry. The stressor consisted in restraining the cows for hoof treatments. Body temperature and heart rate were measured at 0, 10, 20, 30, 40, 50, 60, 90, 120, 180 and 360 minutes during the experiments, and also cortisol assay at 0, 0.5, 1, 2, 3, 12 and 24 hours. Base line for these animals was set in there accustomed environment at -24hrs and -30 mins before the beginning of experiments. The results obtained in this study were as follows:
1. In the BT, heifer group showed no significant difference from cow group, but were observed slightly higher BT than cow group during restraint stress for 30 minutes.
2. The both groups showed directly significant increase of HR immediately after the beginning of the restraint stress (P＜0.01), but in the required time for the recovery of HR after finishing the stress, heifer group was 40 minutes and cow group 60 minutes.
3. In the cortisol assay, the both groups increased from 30 to 120 minutes after the beginning of experiment (i.e, from 0 to 90 minutes after finishing the restraint stress), showing significant difference from before the beginning of the stress (P＜0.01), but heifer group showed great increase of the cortisol level from 30 to 60 minutes after the beginning of the stress, while cow group was observed at 60 minutes.
In conclusion, we suppose that care is required to decrease psychological stress in cattle when they suffer from a series of procedures for diagnosis and treatment, especially in heifers rather than in cows. Also BT and HR obtained by active biotelemetry are reliable indicators of stress in cattle.
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