The Effects of Feed Restriction on Reproductive Function in Swiss CD-1 Mice

Abstract

Many test compounds used in toxicity studies produce a “systemic” toxicity manifested as reduced body weight gain. While it is known that reduced weight gain during juvenile growth reduces or delays reproductive competence, the effects of adultonset feed restriction (FR) and inhibited weight gain on the reproductive system of mice are poorly known. To gain some information on the effects of graded body weight reduction, or reduced body weight gain, on commonly used reproductive end-points, the studies reported below were conducted at two laboratories, using adult mice that were maintained at 90, 80, and 70% of concurrent control body weight (CBW) for up to 21 weeks. Estrous cyclicity and fertility in the females were significantly affected. While male fertility was variably affected, there was a significant decrease in the number of epididymal sperm and in the number of testicular spermatids in the 70% CBW groups. Testis weight was conserved in both studies; relative testis weight increased in all FR groups. These data can improve the interpretation of future studies by helping to separate chemically induced changes from those produced by reduced body weight gain.