Some effects of group size on behavior and physiology of the rat

This experiment was designed to evaluate (1) the effects of housing and feeding conditions on the rat's adjustment to food deprivation and (2) the effects of group size on the rat's response to novel and stressful situations. In the first study 4 groups of animals were subjected to group or individual housing and group or individual feeding conditions. Housing conditions significantly affected the rat's adaptation to a deprivation schedule regardless of feeding conditions. In the second study, animals were deprived, subjected to cold stress, a behavioral test, and immobilization. Group housed animals were less “timid”, more adaptable to restricted feeding, and had lower relative adrenal weights; while individually housed animals showed a lower mean weight loss during immobilization stress.