Answer:
I think it is probably because they were afraid that the slaves would gather around and come up with a plan for either a revolt or an escape. Both of these were not good (in the mindset of a slave owner) because he would lose his slaves, or get a complete revolt in which there would be a lot of trouble and a lot less time for them to work.
This isn't a terrific explanation but I hope it helps, just build on top of the key points and I think you'll be all set.
Hope it helps!
Step-by-step explanation: