Aversiveness of motion and noise to broiler chickens

1. The aversiveness of motion and noise to broiler chickens was examined using a passive avoidance technique. Birds were initially trained to peck a key a fixed number of times to obtain food. After training, food could still be obtained by key pecking, but feeding was immediately followed by 1 min exposure to noise or motion. Birds could delay or avoid exposure by delaying or avoiding key pecking, hence foregoing food. Reduced pecking rate was therefore taken as a measure of aversion. 2. In experiment 1, simultaneous motion and noise, but not noise alone, resulted in a significant decrease in pecking rate in comparison with baseline rates obtained after training. 3. In experiment 2 there was no significant difference in the pecking rates of 4 groups of broilers during training. However, after exposure to 1 of 4 types of motion, strongly significant differences in pecking rates were found between the groups. The mean latency to peak 3 times was significantly greater for birds exposed to gentle vibration, with a single jolt after 55 s, than for birds exposed to simple harmonic motion in either the horizontal or vertical plane. Birds exposed to circular motion in the horizontal plane had a significantly greater mean pecking latency than birds exposed to simple harmonic motion in the vertical plane. 4. Baseline latencies to keypeck in experiments 1 and 2 were longer than expected. In experiment 3 a direct comparison of baseline pecking was made between broilers and laying hens. The hens had significantly shorter pecking latencies.