I have no idea how someone would go about raising slugs. But, there is tons of info on raising mealworms, crickets, earthworms, and maggots. Mealworms can be grown indoors with hardly any odors. And, they multiply like crazy. Raising crickets stinks. I would NEVER raise them in my house.
I grow kale and they love it. It grows like crazy down here as a winter crop. Actually, our chickens love just about all of the cool weather crops.
New Zealand Spinach, Malabar Spinach and Amaranth grow terrific in the summer heat. They are delicious for human peoples too! LOL!! Amaranth is a green that grows like crazy in our horrible summer heat. The greens are fabulous for us and the chickens. The seed heads are huge and the chickens go nuts for those seeds. Some amaranth are grown more for the seeds and other varieties are grown for the great greens. The chickens will eat the greens of both with great enthusiasm!
I know this was a slug question but......