"Other Dairy including milk: Probably is a great option. However it requires labour to harvest the dairy... it is probably more economical to market the dairy to humans directly rather than feeding it to pigs. "
Yes dairy (keeping and milking a cow) takes a lot of labor. However so does growing and harvesting pig feed beyond the grasses they will eat, or buying and shlepping purchased feed for that matter. It's all work/time/money, you just have to decide what trade offs you prefer to do.
Raising an organic cow and selling it's milk will bring a good return. This is why I
sell some of our naturally raised, raw milk to pay for the extra nice cow
hay and alfalfa. The rest of the milk goes to the pigs,
chickens, dog, cats, ducks and geese. I make butter, and sometimes kefir and cheese, but we really don't drink milk. To many years without any natural raw milk and we just got out of the habit. Having a family cow as the bases for one's farm-food-chain makes good $ sense.
"Eggs: Walter Jeffries also recommends eggs. I just don't see these being worth the extra effort of collecting the eggs, caring for the chickens, cooking and feeding the eggs to the pigs. Once again I bet you would make a lot more money by just selling the eggs to humans."
Not so much in my area. At $3 a dozen I consider it less work to feed the extra to the animals instead of cleaning, packaging and selling, but that just me.
"Chicken meat: If you have a large laying flock they would need to be culled which would produce meat for the pigs. This makes sense because I imagine the pigs would do all the butchering for you and not many people want to buy old laying hens for meat so they are not worth much."
I don't like the idea of my pigs getting used to the taste of blood. I have to many animals crossing paths with the pigs to be comfortable with this notion, not to mention the feathers and mess. But I have used this idea of old chickens, to many smallish roasters and skinny ducks as dog and cat food. Feed, is a good use for these.
"Fish: According to a lot of permaculture people fish systems are the most productive... I don't know the source of that information. I have read on these forums that feeding fish to pigs makes the pigs taste fishy... that doesn't make any sense to me and I am wondering if anyone had personal experience with this?
This option does sound easier than feeding chicken
I do not know about it changing the meats taste. However, if you were concerned simply stop feeding the fish a couple of months before butchering just to be on the safe side. Have your pigs finish off on grasses and alfalfa.
"Rats/Small Rodents: I am trying to think of an extremely low cost, low labour way to get protein for pastured pigs... rodents seem to be very productive and low maintenance in my experience. I have never heard of anyone intentionally raising rodents, though. This type of operation would probably have to be kept a secret, due to public paranoia around rats and mice."
Many places and people intentionally raise rodents. I know I did as a kid. Rodents used for schools and science, rodents used for feeding reptiles and rodents raised as pets. But the animal I would select for animal-feed wouldn't be rats/mice, unless we are talking about chicken feed. Then rodents would be just the right size for swallowing. What about raising
rabbits instead?
"There has got to be a better way to raise pigs. Pigs in the wild do not receive any human help... how do they feed themselves a balanced diet? Why cant we replicate that with our pasture systems?"
Wild pigs eat invertebrates such as worms, insects, and insect larvae. And they will eat small mammals, eggs and young of ground-nesting birds and reptiles along with grasses and forages. But you
should remember that pigs in the wild are smaller and leaner, they are not the meaty pigs we love to send to the butcher.