What are the age of your females? Maybe their body are not yet ready to breed, yes they can be mated by the male, plugs can be visible, but it's their body that is telling them not yet.

SOME males eat their off-springs because of stress, jealousy maybe? hahaha But my males are kept together with their respective harems. They are good husbands too, they tend to clean the pups and prepare their nest. I suggest dump the dog food.