As far as sustainable agriculture is concerned livestock is intrinsic to the success of the homesteader and until a few decades ago was considered the normal and wise practice to achieve self sufficiency and independence from out side sources! It's circle is complete!
Domestic Animals vs Vegetarian Agriculture
Here's my take on raising animals. Pardon the esoteric tone but I know of no better way to explain it.
Mankind long ago came to an agreement with the deva or group soul of certain animal species. Let's take chickens as an example. In the wild, what is presently our domestic chicken is apparently a native of the jungles of SE Asia. It is not a common bird in the wild, and is like all animals in the wild subject to predation, drought, disease, and variations in its food supply.
So humanity makes a "deal" with the chicken deva. In exchange for some part of the population of chickens providing us with eggs, meat, feathers etc, we will provide you with shelter and protection from predators, as well as provide a secure supply of good food and clean water. In addition we will apply our intelligence toward the breeding of even better and healthier chickens that are adapted to diverse environments. We will protect you and help your kind spread across the face of the earth.
This is an agreement of mutual respect and mutual benefit to both species, and until quite recently it worked well. Chickens were nurtured by people and spread from a tiny corner of SE Asia to the whole world. The chickens fed the people, the people fed, protected, and multiplied the chickens. (multiplied isn't the word I want, but you know what I mean).
This same scenario applies to all "domestic" animals from dogs to bees to horses: Humans feed, protect, and multiply the allied animal species in exchange for the benefits the animals provide. I fail to see how the animal species loses from this arrangement. There are still wild chickens, horses, bees, dogs, and cattle. The lives of these wild members of the species are different, but are they better? The species mentioned would certainly not be as numerous without their alliance with mankind; is the continuation, spread, improvement and increase of the species not a prime directive of all living things?
What I am suggesting above is that in its pure form, humanity's relationship with domestic animals, just as with domestic plants, is symbiotic, not exploitative. The fact that certain human-appearing entities violated this agreement, e.g. factory chicken production, "puppy mills", cattle feedlots, trucking beehives around the country as pollinators for rent, does not invalidate the soundness of the original agreement.
Sadly, just as has happened with many other greed-based actions in modern society, the exploitative model has become accepted as the norm, when what it truly is is an ethical aberration and moral cesspool.
What would be the consequences of following the advice of strict vegetarians, vegans, and eliminating all forms of so-called exploitation of animals? The horse clan provides us with an example.
Up until the 1900s, the horse was the main motive power for all of mankind. Horses carried us on their backs, pulled our carts, plowed our fields, even turned our machinery. For the most part, humans cared very well for their horse allies; we needed them. We also bred them for strength, for running ability, for stamina, and we nurtured them and spread them around the world.
In the early 1900s horses began to be displaced by combustion engines. When people bought a car, they got rid of the riding and carriage horses. When farmers bought a tractor, they got rid of the plow horses. A sad note is that during the 1930s in the USA, the tractor manufacturers, in order to sell their machines to as many farmers as possible, offered a trade-in value on a new tractor to any farmer who turned in their farm workhorses. The farmer got a new tractor, and the horses were shipped off to the slaughterhouse; they were worth nothing to the tractor dealers, who were just offering the trade-in as a gimmick to sell tractors.
The loss of millions of these animals, each the result of hundreds or thousands of years of care, breeding, and nurturing, the loss of this incredible resource, diversity, and gene pool, is shocking. Thousands of years of symbiotic alliance was tossed on the trash heap overnight.
And today, how many horses are there? Is the collective spirit of the horse clan pleased with this? Is it now at peace because very few members of the species are now being "exploited" by humans? I would suggest that the spirit of the horse clan is not particularly pleased by this turn of events.
As long as the agreement, the agreement of mutual benefit, is kept, I fail to see how either species is exploiting the other. If the majority of humanity stopped eating chicken and eggs tomorrow, how many chickens would be left worldwide? How many would be kept as pets? Probably far less than the amount of horses being kept as pets these days. And what about the loss of that worldwide genetic diversity and adaptation to various niches? Throw that on the trash heap so as to avoid further "exploiting" another species?
Again, we can apply the same logic to domestic plants, can we not? Are we not "exploiting" wheat when we plant and grow it for our own benefit, just so we can eat the fertile embryos that are its seeds? Would it not be morally superior to stop this abuse, quit planting and exploiting wheat for its babies, and let things revert to their natural state? Would it not be best of all to never eat another wheat baby?
I submit that the problem lies with those who have violated the original partnership, those who have introduced factory farming of animals and now genetic modification and extreme hybridization of plants, all in the name of greed. Previous to this time, when mankind selected plants or animals to multiply, the selection was based on criteria that benefited both species. Factory farming of animals does not benefit the animals in any way, nor does extreme hybridization or genetic modification of plants benefit the plants. THAT is exploitation. The original agreement is a partnership.
Another point: The argument is often made that much of the cropland, in the US at least, is devoted to growing grain to feed to animals, and that if this practice were stopped there would be plenty of grain to feed all of the hungry people of the world. Putting aside the questions of whether we want to feed all of the hungry people of the world so they can have another population explosion and whether or not it's possible for humans to live on grain and vegetables alone, there is one very valid point: Why are we devoting such a large percentage of cropland to growing food for animals?
Much of this could be eliminated by ending the feeding of grain to cattle, the extremity of which is the feedlot where eighteen month old steers and heifers are fattened for a few months before slaughter. Complicated subject, but in essence cattle are not meant to be nor well adapted to being grain eaters. It is unhealthy for them and their meat and milk becomes unhealthy for those consuming it as the fatty acid profile is altered (see CLA). What has happened since WWII is that some people figured out that they could cheaply buy yearlings from the ranchers who raised them on grass, then feed them cheap grain in a confined situation for a few months, thereby greatly increasing the weight of the cattle and making a quick buck. Again, greed, and again, violating the agreement.
Going back a hundred and fifty years, even in prosperous agricultural communities, little grain was raised to feed domestic animals. Chickens ranged free eating bugs and worms and plants; hogs ranged free in the woods and towns, digging up and finding the majority of their own food. In the Foxfire books someone writes about how hogs were raised in the old days in Appalachia. The piglets were free-range from the time they left their mothers. Household food scraps would of course be given to them, but they learned to forage in the woods as spring led into summer. When early fall came, the acorns and other nuts dropped from the trees and the pigs grew fat gorging on them. In late fall the hogs were rounded up from the forest and the outskirts of the village. Selected ones were butchered and made into ham, bacon, sausage. Their hides were taken and tanned; the scraps and bones were food for the dogs, with the bones eventually providing Calcium and Phosphate to enrich garden soil. The best of the breed were kept, fed and sheltered over the winter, in order to start the cycle again next spring. Pigs ranged free, as did chickens and other domestic fowl. Not only did they provide much of their own food, but their meat and eggs were healthier.
The strongest argument for raising domestic animals as food, however, is that very little of the Earth's surface is suitable for the growing of crops. Only flatland with a slope of less than 2% is really suitable if one is to avoid serious erosion, and in addition not that much land, even if it is flat, is of sufficient fertility to make the growing of crops worthwhile, nor is the soil deep enough, nor is the rainfall sufficient, nor is it likely to be free enough of rocks to even contemplate cultivation. What it is suitable for is for grazing and foraging. Take a look at the various peoples of the world who have lived healthy and abundant lives for millenia as herdsmen on land that is completely unsuitable for row crops or cultivation at all. Their animals are healthy and content, and grazing, well managed, only increases the fertility of the land.