That sounds like a similar principle to what John Seymor talks about in his book "Self Sufficiency". He talks about how the different types of animals benefit each other and the farmer over all. He also talks about readying the field for plowing after you've had cows, goats/sheep, and chickens by having pigs plow your field for you! I never heard of that concept before. He puts a lot of emphasis on creating your own farm ecosystem and sustaining it, with high value on the animal manure to dress the fields, crop rotation, growing your own animal feed, and avoiding monoculture.