You said we fed them crops, if we are feeding them crops those crops are likely not grass/hay, and thus they're likely easily made edible for humans.
Regardless, you make the claim we couldn't feed them, which in fact we definitely can, especially because we throw away most food we purchase (in the west), it's just not profitable to do so. Transportation is hardly an issue compared to them taking 10-30x more resources (to feed the animal to produce the same calories).
Sorry if I'm rather aggressive; I come from a community where people aren't really worried about public opinion and really have no fear in starting an argument, which many people don't want to argue here.
I understand the topic was about Animal Agriculture, but wouldn't it make more sense to genetically modify or otherwise develop the crops to withstand those conditions rather than the animals?
You said so yourself that it'd problematic environmentally and dirty, so why not just improve the plants, which would be easier, than focus on "improving" animals when it's not only inefficient to base one's diet off their secretions/bodies but it's also environmentally bad and arguably extremely unhealthy, especially if done in a more efficient industrial manor.
You have a point, but try consider 3rd world countries too. You should understand that it is another seprate setting there; i know of a village in Africa (Name witheld) they live on cattle and sheeps, no forages......and if you had read to the end, you will notice this is a series, and the crop part is the next episode.