You are wrong. Goats have not "evolved" to survive on weeds and brush. They always survived on weeds and brush.
Until we domesticated them and started feeding them other things. There are still breeds that do well with mostly forage, but we have tinkered with breeding and made it so that in order to get the production wanted, they need that better quality feed. Dairy goats in particular need a bit of extra in order to "put it in the pail" to the extent that a lot of people want.
Besides, they are talking about sheep, not goats.
Until we domesticated them and started feeding them other things. There are still breeds that do well with mostly forage, but we have tinkered with breeding and made it so that in order to get the production wanted, they need that better quality feed. Dairy goats in particular need a bit of extra in order to "put it in the pail" to the extent that a lot of people want.
Besides, they are talking about sheep, not goats.
