It did occur but the word forced is misleading. Jimmy The Greek was fired and discredited for telling an ugly truth on national television, one that goes against foundational principles in this country. Doesn’t mean it didn’t happen, though.
Sounds like a Myth:
https://en.wikipedia.org/wiki/Slave_breeding_in_the_United_States
>Robert Fogel and Stanley Engerman reject the idea that systematic slave breeding was a major economic concern in their 1974 book Time on the Cross.[17] They argue that there is very meager evidence for the systematic breeding of slaves for sale in the market in the Upper South during the 19th century. They distinguish systematic breeding—the interference in normal sexual patterns by masters with an aim to increase fertility or encourage desirable characteristics—from pro-natalist policies, the generalized encouragement of large families through a combination of rewards, improved living and working conditions for fertile women and their children, and other policy changes by masters. They point out that the demographic evidence is subject to a number of interpretations. Fogel argues that when planters intervened in the private lives of slaves it actually had a negative impact on population growth.[2]
It didn’t seem likely to be because human couplings are much harder to control than animal ones. Women don’t have periods where they’ll absolutely become pregnant making the whole practice too costly to do.
That and the maturation period for humans of 15-20 years is way too long to learn how to select for characteristics with any usability especially in the 1800s.