Diet restriction through hopper design (1999)

Wrightson, D., Dickson, C.

Abstract

Group-housed rats were induced to 'work' for their food by soldering metal plates over their food hoppers, so that only 3% of the original area remains available. The animals fed for longer periods and rested less during the night, but there were no adverse clinical effects and no problems with rats' muzzles, gums, teeth or forepaws. The rats were not aggressive to one another or to humans, and were more confident when handled. No changes were observed in the rats' social hierarchy and there were no increases in fighting with restricted hoppers, as up to three rats could feed at a time. .... It was felt that this method of food restriction was preferable to giving less food [to avoid obesity]. ... Rather than rapidly eating a reduced ration and feeling hungry for long periods, the rats worked harder for their food, which enabled them to burn more calories and eat throughout the day. This reduces the incidence of obesity and its associated disorders and also encourages more 'natural' behaviour patterns, both of which improve welfare.