Effects of room temperature on reproduction, body and organ weights, food and water intake, and hematology in rats.

Two generations of rats were raised at animal room temperature ranging from 12 to 32 degrees C at steps of 2 degrees C. The body weight of rats born in 22 degrees C environment and exposed to each temperature did not significantly differ within the range of 16-28 degrees C. The delivery rate, litter size, and weaning rate decreased at 30 degrees C and 32 degrees C, and only the weaning rate had a tendency to decrease at 12 degrees C. No significant difference was demonstrated within the 14-28 degrees C range for any reproduction parameter observed. The body weight of sucklings did not differ at birth within the 12-32 degrees C range; and at 3 weeks of age, there were no differences within the range of 18-28 degrees C. The body weight gain in both sexes after weaning was generally small when the temperature was below 18 degrees C or above 30 degrees C. There were no significant differences in food intake within the 20-26 degrees C range, in water intake within the 12-26 degrees C range, in hematological and serum biochemical values within the 20-26 degrees C range, and in organ weights within the 18-28 degrees C range. Therefore, the range of 20-26 degrees C (68-78 degrees F) was the optimum temperature range in rat rooms.