[Non-Sequitur]

On the other hand, slaves would have required considerable upkeep, would they not?

What upkeep would they really require? Food was rudimentary and grown or raised on the plantation iteslf, by slave labor. Clothing was nothing fancy and certainly not expensive. Slave housing was not a recurring expense. The upkeep of a slave amounted to very little and in return you got an investment who worked for free, could be sold for a good profit, and who if paired with another slave could crank out additional assets every 9 months or so.

[neverdem]

The upkeep of a slave amounted to very little and in return you got an investment who worked for free, could be sold for a good profit, and who if paired with another slave could crank out additional assets every 9 months or so.

Nine months is unrealistic when nursing babies. Once the babies are weaned, or they had a wet nurse, the mothers could resume ovulation once her prolactin level decreased enough.