I give them a good feed in the evenings, and usually chuck in a rabbit or two, and sometimes a bit of dry (there are ten ferrets together), They eat as they please, and sometimes even get the odd bit of kidney etc during the day if im feeling generous. They work because they love to hunt. Having said this, none of my ferrets are over fed, they are always ready for the grub when it hits the courts floor, and you can tell that they are fed enough to be strong and healthy, but not enough to make them slow and lazy.