I'm looking at building a food forest, and was wondering what breeds of animals will make the best "lawn mowers", but leave my trees/bushes "alone".
Goats are incredible. Depends on what kind of shrubs and trees you have. If goats are fed regularly they won't necessarily destroy, just prune. Rabbits are great at pruning the underside of shrubs. Again, trouble is augmented by feeding them...although I don't necessarily recommend feeding bunnies...
The underside of shrubs usually produces little food for the shrub as there is less light reaching those photosynthetic leaves. Rabbits do well until one bright little shit starts pulling down branches to strip them. Bunny fencing, chicken wire installed around plants you don't want pruned is incredibly effective. I know 'cause I've been feeding my wild bunnies and now I have an awful lot of bunnies...ohhhhh, baby bunnies!! I've got blueberry shrubs and a huge garden, all blocked from bunnies and deer. Nice harmony at present. I might need to pitch my tent later until I get better fencing...grins. Otherwise, feeding wildlife will help to keep them happy and not into digging under fences. I keep a few bales of hay outside the perimeter of our property for deer. This can be viewed as a good or a bad thing. When living in a transition zone with wildlife I think it works very well and very entertaining/educating.
Oh, bunny fencing has to be buried 4-6 inches beneath the surface of the soil! Works very well. I am the idiot to start feeding the bunnies and now have an awful lot of bunnies who are proliferating and it is lots of fun when a herd of bunnies come running at you instead of away. The cutest thing are bunnies so comfy and secure they can stretch out with their back feet getting some sun. I've learned bunnies are nature's damn convenience food for predators. One gets inured to daily missing bunnies...or raptors carrying off beheaded baby bunnies (lighten the load)...sigh. Their little poop pills fertilize this pumice soil, giving nitrogen to the decomposers, improving the native crap soil and our pines are doing far better than others.
Rabbits can dig but prefer to use tunnels and hidey holes made by other creatures rather than dig their own. Very interesting creatures. Great parents, lots of babysitters, sentries...so what if the babies aren't their own! The thumping thing is a marvel.
Goats are great in the more wild areas of property, not around a home with landscaping. You are the best option for control of artificially created landscapes. Unless you live in the wilderness, NO animal can do the work better than you for artificial landscapes. Get some books on pruning, forget getting animals slaves, grinning widely!