The effects of group-housing and relative weight on feeding behaviour in rats

Abstract

To meet the growing concern for the well-being of laboratory animals, group-housing is now recommended for rats. The aim of the present study was to examine the effects of group-housing and relative weight within the group on feeding
behaviour in rats. Studies of the individual feeding behaviour of group-housed animals have been carried out in many farm animals. In these studies, when effects of group-housing and hierarchy on individual feeding behaviour are studied, the
results are often confounded by differences in age, body weight, genetic differences and earlier experience of the animal. All these factors were standardised in the present study. The individual meal patterns of 12 male Sprague-Dawley rats, of
the same weight and age, housed singly were compared to their meal patterns after two weeks of housing in groups of three per cage. The feed intake and the feeding behaviour were recorded by computerised balances in combination with time
lapse video recordings, during the group-housing period. Although when group-housed the rats made the same number of visits to the food cup as when housed singly, they ate more quickly, ate less per visit, and hence spent less time per day
eating. The increase in eating rate was significant for the rats assigned to be the medium weight or lightest in their groups but not for the rats designated to be heaviest in their groups, indicating that the relative weight of the rats had an effect on their eating behaviour.