Two experiments were carried out to determine whether lighting conditions during handling affected heart rate or behaviour in farmed red deer. In Experiment 1 heart rate was measured in 24 individual deer, held under restraint in a mechanical deer crush for two minutes, under either dark (0lux) or light (1500lux) conditions. A stethoscope was used to monitor heartbeat which was indicated vocally by the stethoscope operator on to a Dictaphone. In Experiment 2, 10 groups of three deer were confined for four minutes in an unfamiliar 4×6m light-proof pen with lighting provided either on the left or right-hand side of the pen, to provide a gradient across the pen from approximately 12 to 1000lux. For the first two minutes the deer were alone and for the second two minutes a person stood in the pen. An infrared video camera was used to record behaviour.

In Experiment 1, heart rate was lower (P < 0.05) in the dark compared with in the light when recording commenced, thereafter it decreased overall with similar (P > 0.05) values observed for the different lighting treatments. In Experiment 2, the mean position of the groups across the pen varied according to whether lighting was on the left or right, with groups displaced to the right when the lights were on the left, and standing in the middle of the pen when the lights were on the right (P < 0.05). During testing, groups moved away from whichever side the lights were on (P < 0.05). The experiments suggested that stress during restraint was reduced by providing darkness and that deer preferred dim lighting compared with bright lighting when confined in unfamiliar surroundings.