Effect of sequential bleeding on body weight gain in rats

Monthly withdrawal of a total of 1.25--2.0 ml of blood from young, mature, inbred Fischer 344 rats produced no noticeable effects on common hematologic parameters, but it did cause a decrease in the rate of body weight gain. The difference in body weight between rats bled and not bled was evident 3 weeks after the study began, and the difference persisted throughout the 23-week study.