1. the smaller the animal, the more efficiently they convert sunlight to meat (rabbits are the most efficient human regularly consume)
2. they can survive off of margin land, whereas cattle need straight grass
3. goats would be optimal, but are impossible to train to a 1 wire rotational grazing system. They need at least 2 and most likely 3/netting
4. most ewes have twins and triplets are even possible.
5. taste way better
6. If you live in a wet climate, they're lighter and won't pug up the ground. Which also means you can graze riparian buffers more frequently.
7. Highly unlikely to get injured by a ram.
Don't get me wrong, cattle and beef have their place in our system, but there is a reason lamb and goat consumption used to be way higher in the US before subsidized agriculture.