The effects of food restriction on the welfare of sheep are as yet unclear. An operant crate and a push-door were used to measure feeding motivation in sheep after 0h, 6h, 12h, 18h and 24h without food. In experiment1, sheep had to push a panel with their noses to obtain a food reward.
In experiment 2, sheep had to run a race and push through a weighted door to reach food; the time taken to reach various points was recorded and the work performed to push through the door was calculated. In experiment 1, 3 out of 12 sheep became trained to push the panel and there was
a difference in the mean number of rewards/session obtained by each animal (P < 0.05). There was no effect of treatment on the number of panel presses performed. In experiment 2, 10 out of 14 sheep were successfully trained. More sheep went through the push-door when deprived of food (P
< 0.05), and they were quicker to enter the race, reach the push-door, and reach the food than those which had not been deprived (P < 0.0001). They also spent less time pushing the door than non-deprived sheep (P < 0.0001). The push-door was a more appropriate method of measuring
motivation to feed in sheep, as more sheep learned the task in less time than for the operant crate. As measured by the time taken to enter the race, reach the push-door, push through the door and reach the food there was an increase in feeding motivation after only 6h without food.