I would agree that the methods common to factory type farming are destructive to the land and lead to soil exhaustion, but that is a relatively recent deviation from traditional farming. Where farming occurs is equally important. One of the biggest milk producing states is California. Not because it is a good place to raise dairy cows but because the milk subsidies from the government encourage farming in places that would not occur under normal circumstances.
It is difficult to find a dairy farm in Minnesota today, although it is far better suited for this.
Using Corn for producing fuel is about as inefficient as it gets so now we have millions of acres growing a monoculture of fuel crops. No animals to replenish the soil, but more petroleum based fertilizer is used to make a petroleum substitute. Not much future in that either. Subsidies keep that practice alive also.
The argument that animals feel pain as a result of slaughter is certainly true, but animals raised in the traditional way have an excellent life otherwise. They do not face starvation, disease, constant preditation, etc. There is always pain and cruelty involved with life. That does not mean we should not try to minimize the experience, much like it is done with child birth and surgery.
I have watched a house cat torture mice, birds for hours. That is their nature. It should not be ours, but the harmony with nature thing does not exist as presented. Nature is every bit as cruel as humans can be, and you can't get around that fact. I have seen deer dragging their guts in the dirt due to a wolf attack or a Red Squirrel biting the testicles off of a Grey Squirrel "ouch". Nothing pretty or harmonious about that. It is reality, but if you live in the middle of Chicago you probably are not aware of how things really are in nature.
You probably have not witnessed a mother rabbit killing its offspring because it has a defect. Humans do not normally do that. Nature does.
Nature is not like a Bambi movie, it is often ugly, cruel, painful but that is part and parcel of life in general.
Dan