The behaviour and movement of dairy calves in low light intensities

Abstract: According to the Swedish welfare act, cattle stables must have inlet of natural light and artificial light that do not disturb the animals’ natural behaviour and diurnal rhythm, dairy cows should also be provided with light at night. However, there are no specific recommendations on light programs for calves. In this study, the behaviour and movement of 12 female dairy calves were assessed in four different light intensities (225 lx, 5 lx and 0.5 lx in white light and 0.5 lx in red coloured light) during two weeks. The experiment had a changeover design with three calves allocated to four groups. The calves within one group followed the same test order but were individually tested. On average, the calves were 11.5 weeks of age and 3.5 weeks after weaning. The response was evaluated by first enticing the calves to pass through an obstacle course where time in the obstacle course, number of steps and number of contacts were measured, and secondly by a novel object test were six different behaviours, time until first contact, number of contacts and mean length of contacts were recorded. In the obstacle course the calves took significantly (p<0.05) more steps in 0.5 lx red light compared to 5 lx. In the novel object test, the calves moved the novel object significantly more in 225 lx compared to 5 lx (p<0.01) and 0.5 lx red light (p<0.05) and significantly less in 5 lx compared to 0.5 lx white light (p<0.05). The results also showed a tendency that the calves moved the novel object more when they were tested in their third or fourth treatment. In conclusion, only few significant effects were found between the treatments. This suggests that calves can cope with intensities down to 0.5 lx without large significant effects on their behaviour or movement. There were no significant diffences in willingness to pass the course or on the behaviour in the NOT between white light and red coloured light in 0.5 lx.