I agree that meat farming, at least in the factory-style, is horrific. But this solution seems like it might make things worse.

If there's a meat tax, then farmers will have an incentive to cut even more corners, which might lead to even more cruel conditions.

Instead, maybe it makes sense to set a price floor for any operation over a certain number of animals. (IE, if you have more than 200 animals on your farm, you can't charge less than $10 a pound or something).