not at all, each time a mob goes to eat, they'll only eat one item in the stack; Do take care however, that unless the dropped items are still within range of a crafting station they are liable to despawn after some time( possibly an hour) while you are away. also, if you really want to keep them breeding efficiently, you will need to remain nearby and ensure you are culling them as their population goes up, and also because they don't accumulate "love points" while you are too far away.

Each tamable animal has a limit on how many others can be nearby before they stop mating, I would reccomend looking up an animal breeding build to help you overcome this population limit by having the breeding animals at an elevated position so that they babies fall to the ground far enough away they aren't counted in the breeders population limit.

It can take a lot of time to set up, but once you have it up and running, you'll be swimming in meat!

I have a breeder pen for both boars and lox currently, and have plans to double up on the boar setup to add chickens further up in the structure I have built.