So you think because a domesticated animal has food given to him,he will not act upon instincts?<quoted text>
Because domesticated animals aren't practicing for anything and would most likely die if they had to live on their own.
That cat knows there is big bowl of fancy feast waiting. No reason to kill the mouse and then walk away.
Do you think dogs and cats have this much thought going on? Hell, most humans do not have this much thought going on.