Final answer:
The detail indicating that slave children were not fed enough is the description that shows a struggle for food and that few were satisfied after eating, pointing to insufficient provisions.
Step-by-step explanation:
The detail from the passage that provides evidence that the slave children were not fed enough is "...he that was strongest secured the best place; and few left the trough satisfied." This statement directly suggests that there was a struggle to access the food and even after that struggle, most did not have enough to eat, indicating that the provision was insufficient. Furthermore, the use of a common trough and the lack of utensils imply a lack of individual portions, which would ensure each child received a sufficient amount. Finally, the comparison to pigs portrays a dehumanizing method of feeding, which typically does not prioritize the well-being or satisfaction of those being fed.