> First, this is an incorrect comparison: chickens eating corn VS humans eating wheat bread. Humans can very much eat corn as well.
I mean, it compares what it compares. From a land usage and calorie perspective chicken is approximately equivalent to wheat.
> Also, the environmental impact needs to account for water usage, pollution from the plant and animal farming and energy usage.
Yes, I am not accounting for those. The first reason is that I am lazy, and this is a comment on the internet; the second reason is that once you are trying to optimize for land usage, water usage, energy usage, fertilizer usage, human labor, capital costs, run-off pollution, CO2, and everything else, you now need to decide how to weight each factor.
Rice produces almost 3 times as many calories per acre as wheat, but uses more than 3 times as much water (449 gallons / lb vs 132). Which is better?
> Second, you have to consider the conversion rate for each nutrients including calories and proteins and chickens are much less efficient than that.
This is actually where chicken excels.
I should really be comparing chicken to soy, not wheat, because soy is a great source of complete protein.
If you plant 3 acres of soybeans, you'll get 18 million calories worth of soybeans.
If you plant 2 acres of corn and 1 acre of soybeans, you'll get 36 million calories of grains, and if you feed them to chickens, you'll get 12 million calories of chicken.
On a calories-per-acre basis, soy is beating chicken 3:2. But soy only gives you about 0.1 grams of protein per calorie, while chicken gives you more like 0.2 grams of protein per calorie.
So your 3 acres of soybeans give you 1.8 million grams of protein, while your 3 acres of corn+soy->chickens give you 2.4 million grams of protein. So chickens beat soy on protein per acre by 4:3.
> Please provide evidence sources if you want to claim otherwise.
I've stated all the numbers I'm using; if there's one you want to call bullshit on in particular let me know.