> semi brainless cows ... it's the ethical thing to do

A second way to make it ethical in terms of animal suffering is to effectively start eating road kill. That is, you raise a farm of cows, treat them well, and eat them when they die naturally.

A third way is to raise a farm of cows, anaesthetise them via their food when they're old enough, and kill them in their sleep. It's more debatable than the above but I believe it's ethical as long as it's done right (which it won't be, in practice).

This all of course ignores GHG emissions and loss of biodiversity due to the need to produce large amounts of feed and large uses of land. But speaking strictly from the cow's perspective, I think it is ethical.