This article is from the WSSF 2017 AFRMA Rat & Mouse Tales news-magazine.

Did You Know?  Adult female rats fed a diet high in salt produced more females in their litters. The amount of salt did not affect litter size or general health of the offspring. [Do not try this at home. A high-salt diet can cause many health problems. Ed.]

Published in Physiology & Behavior, Volume 36, Issue 2, 1986, Pages 307–310, Maternal dietary sodium chloride levels affect the sex ratio in rat litters.