If the end goal is meat, I think there are a lot of places where gains in efficiency are possible.
That's my point. I think you can get much more off of a square of solar exposure than just meat. And I think a cow is more than a meat factory. The cow's life is intrinsically valuable, and especially if we can have a relationship with the cow, it can make our lives more valuable.
Let's say you succeed in making a beef factory that's more efficient than an optimal cow pasture. Great, what are you going to do with the extra space? Make a movie theater? A theme park? A nature preserve? A cow pasture is a nature preserve!
I think a cow pasture is actually pretty nice. I don't think we need nearly as many of them as we have, and we could stand to eat a lot more plants, but I don't think replacing the cow pasture with a meat machine is really a step forward.