Effects of lighting on heart rates and respiratory rates in Calves
Abstract: This study aims to see if light intensities can affect calves’ physiological reactions to their environment, in this case an obstacle course and a novel-object test. An additional red light setting compared to a white light was also tested in low light intensities. Twelve 2–4 month old heifer calves were used. Two tests were performed in succession; an obstacle course followed by a novel-object test, under four light intensities; 225±20 lx (full), 5±0.7 lx, 0.5±0.2 lx and 0.5±0.2 lx in red light. Heart rate and respiratory measurements were taken before and after the obstacle course and after the novel-object test. The overall results showed an increased HR in 225 lx and 0.5 lx in red compared to all other light intensities (p<0.05), whereas 5 lx showed the lowest heart rate compared to all other light intensities (p<0.05). Results from measurements taken before the obstacle course showed the largest increase in heart rate in 225 lx and 0.5 lx red (p<0.05). For measurements taken after the obstacle course, 225 lx gave the highest heart rate course (p<0.05), 0.5 lx and 0.5 lx in red were intermediate (p<0.05) and 5 lx gave the lowest (p<0.05). After the novel-object test there were no differences in hart rates, these were all lower than both before (p<0.05) and after (p<0.05) the OC. There was no effect of light intensity on respiratory rate. However, the respiratory rate was higher after the obstacle course independent of light-intensity (i.e., treatment) (p<0.05). There was no difference in respiratory rate for the measurements taken before the obstacle course and after the novel-object test. In conclusion, 225 lx and 0.5 lx red gave an increase in heart rate in calves before the obstacle course. After the obstacle course, the full lighting (225 lx) had an increasing effect on heart rate, while the effect of both low light intensities (0.5 lx and 0.5 lx red) heart rate was intermediately high. There were no treatment effects on heart rate during the novel-object test. There were no treatment effects on respiratory rate at any measuring point.
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