Body weight gain and food intake alterations in crowd-reared rats.

The effect of being reared in a crowd for 6 continuous weeks postweaning on body weight gain, food intake and gland weight (thymus, adrenals and testes) was studied in Sprague-Dawley adult male rats. Crowd-reared rats (10 per cage) showed a significantly lower body weight at the end of the crowding period as compared to control rats (5 per cage). After 200 days of being reared under the same conditions (5 per cage), the body weights of crowd-reared rats were still significantly lower than those of control rats. However, the body weight gain during this period was the same for both groups. Crowd-reared rats also had significantly lower thymus weight and higher adrenal gland and testes weights as compared to those weights of control rats. In addition, food intake was similar for both groups.