"This behavior is rewarding but that behavior is not."

Basic instinct.

"That's how we do things like train dogs, we rely on their ability to reason."

We rely on their abilities to do what we trained them to do. That's not reason or morality.

"When a field mouse eats its young it does not just randomly eat some just because it is hungry. It consumes the weakest members of the litter."

Agreed. If we did that, there would be no cure for diseases because we'd just let the weak die.

"If field mice were able to intellectualize this behavior on the level of humans, I would suggest that one of their 'moral codes' would be something to the affect of "It is better for all of us if we sacrifice our weak children in favor of our strong children.""

That is not morality. That is once again instinct.

Here is a definition of morality from dictionary.com: " founded on the fundamental principles of right conduct rather than on legalities, enactment, or custom: moral obligations. "

"We intellectualize ideas like "We should put segregate out our smart children into accelerated learning courses because it will allow them to blossom and benefit our economy as a whole because we'll have stronger students/employees.""

This is not morality. This is reasoning. Key word: intellectualize. You compare this practice to sacrificing a field mouse's young. That would be fine except we don't push our (according to your definition of) weak down. We may focus on "strong", but it does not mean we "kill off" our weak.