> most of people can't afford cow's meat anymore. Most people are living on pasta and eggs, eventually they eat pig and chicken but that's getting rare.

It shouldn't be cheap. The world got used to the luxury of cheap meat by being unethical and harmful to the environment (humans' environment) and animals.

Cows are insanely resource-intensive to farm, bad for the air, bad for the water, bad for the land. Factory-farmed chicken meat is infamously inhumane, using genetic mutants to produce more meat faster, as well as being bad for the environment. They require more land and water use just to produce the feed for the animals. Both produce toxic runoff that goes into our water and land. Drugs pumped into animals land in us or our water, causing cancer or breeding superbugs. And we accept all these negatives so we can buy a cheap burger we don't need (we have plenty of other food).

Pigs are actually pretty sustainable, as are rabbits, goats, and venison. We used to eat a lot more of them, before the factory animal farms changed our diets to prefer cow and chicken.

How are pigs, rabbits, goats and venison more sustainable? Unless you mean eating meat twice a year.

I live in a farmer family; our cattle needs around one hectare each, because we don't feed them processed food, only grass; because concentrated food is even less sustainable, and more importantly, more expensive than letting them roam (fenced areas)

Rabbit is not sustainable. There were some people trying to commercially rise and sell them and it didn't work. They would need concentrated food, which is expensive.

Goat meat is much more expensive than cows because they are less efficient than cows and pigs and chicken. I know two people who rise goats to sell them, and it doesn't make them money; really, they do it because they kind of like the critters as a pet project.

Only pigs and chickens are more sustainable, precisely because of theirinhumane(?) short life and their genetics. They are very efficient meat producers.

I know poor people who rise chickens and pigs; those animals take longer to reach "maturity", and the meat is not tender; but since the animals are eating whatever they scavenge, it can't be done at scale; again, we would eat meat like twice a year (This might be an exageration, but chicken pig and cow farms really produce all the meat we eat; of those only cows eat grass under the sun)