There was a huge range, from the very minimal, to owners who would let slaves buy themselves free, kind of a retirement benefit.
If owners were savvy businessmen, they would recognize the cost of keeping the elderly was no benefit. Letting them buy their freedom would have been a very good incentive, and cost effective. However, it would have been admitting the slaves were actually people, and owners tended to not want to believe that.
Some were not only allowed to buy themselves free, but we’re also allotted a parcel of land.
That is the very top of the spectrum.
There were owners who chose, which slaves would breed, for optimum offspring.
Women were used, well, women were used, lots.
Have you ever seen the miniseries Roots? It is a docudrama based on the actual family history of slaves from one particular young man taken from Africa, right up to current times. Alex Haley followed the family stories of his heritage through generations, finding documentation to support those stories, right back to a teen boy stolen from Africa.
It is an amazing story, and the miniseries is chock full of stars.