Since people say that comfrey can survive everything, can comfrey survive a daily stampede to the milking barn as ground cover in the alleys?
Look, I was raised on a wilderness ranch with cattle, horses, sandhill cranes...heaven. No electricity!! 6000 acres a pristine pond/spring where 'Mares Eggs' grew...rare. No ATV'S. We did have a funky Willy jeep to play with otherwise it was all done via horse back.
All my life I've raised plants, taken care of other people's landscapes, trained others to take care of the landscapes correctly. I design landscapes...not as a designer but as a Landscape Architect. Making the landscape functional and desirable to use was what I did 8 years of college, taught classes and took a 4 day long test to be able to have the authority to make opinions. One of my claims to fame is grading and drainage, done without the help of a computer. I am telling you if you are putting the sheep through a bottle neck to guide them where you want you will have MUD. Sure as sheep poop, you will have mud. Mud turns into concrete. Sheep, farm animals when being moved around do not need to eat in transition. Bad habit. Like allowing your horse to go graze as soon as it spies something green and lush when your horse is on duty beneath you. Not cool.
Why not keep it simple for yourself and the animals and install gravel? You'd never regret good old crushed 5/8 minus 4 or 6 inches deep. For this application I would NOT install landscape fabric beneath the gravel. The sheep could easily get caught up in the fabric perhaps at the edges once all turns to mud. Have you ever owned sheep?
Comfrey is a tender perennial. Not made for traffic of any kind. Maybe fine for a stampede ONCE a year but that is it. Mud holds fungal spores that love a plant like comfrey...powdery mildew, rust. I would make a specific area to grow your comfrey. Make your utility areas separate, usable and easy to clean.
WHY do you want to grow plants in a movement zone? What are you seeing as a benefit? Maybe that would be helpful! You know the acronym KISS? Grins!! So true. I applaud what you are doing but you are setting yourself up for failure. Failure is good experience in little bits but won't endear farm life to you at all if there are too many re-dos.
And you do know that comfrey shouldn't be ingested willy nilly, yes? Best used for topical care, not internal stuff. Comfrey is an accumulator plant. Sure makes great organic matter super for adding to the soil! But there are heavy metals in our skies that are in our soils and water. Comfrey...hey, kale is another accumulator plant. When the comfrey is added to the compost the heavy metals are not such a good thing. Accumulator plants suck up stuff animals should not be eating. If you were to send a sketch of your acreage with simple 'bubbles' to designate use and movement, transition zones between uses... we might be able to help a bit more.
Completely within this site's parameters...'landscaping', humans assigning uses to their outdoor rooms, providing connection...yadayadayada. And everything I have read about the uses for comfrey sheds a bit of healthy doubt for this newbie fad.
FYI: The comfrey I'm talking about is the kind that doesn't reseed. I'm not familiar with other kinds.
I'm pretty sure a very strong and well-established comfrey plant could indeed live through a stampede (or several; daily or a regular basis might be pushing it), since it's the roots that keep them alive. However, in my experience, you can't count on every comfrey plant you plant to be that strong. It would need a lot of sun to get that strong (and it would probably grow best next to a rarely traveled sidewalk or the south side of a house). Alleys wouldn't be ideal for that reason. It also takes years to establish them well, it seems.
Comfrey plants are too tall (~3 feet) to walk on comfortably, and a walked-on bush (they are bushes) probably wouldn't look great. Walking on them would break the stems and smush the leaves. Although they really can be very hard to kill once established, that doesn't mean the leaves and stems are tough (they're not; they're easy to damage). Plus, they attract bumble bees like crazy. A human would probably get stung walking through comfrey bushes (I don't know about cows), except that bumble bees probably like lots of sun, too.
I've never attempted mowing comfrey on a regular basis, but even if you could do it, you probably wouldn't want to mow it short (if you wanted something green left that looked semi-decent). Mowing a weak bush might kill it. I don't know if even a well-established comfrey bush would survive being short on a continual basis.
In short, you could probably spend loads of time and effort attempting it, with maybe marginal success, but I seriously doubt that it would be worth it at all, as they would be more like dangerous obstacles than ground cover. Your success might be higher with the kind that reseeds, since you could breed them.
Nevertheless, at least some plants (especially weeds) can become acclimatized to being stepped on (they grow flatter and tougher). I don't know if comfrey is any better or worse at acclimatizing to it than other plants, but it's not the easiest plant to imagine this with.
Comfrey goes dormant in the winter. (All the leaves and stems die.) So, it's not like grass there.
Comfrey has toxins in it. I'm not sure if they'd be a problem for cows.
You might stick with grass or such. There are many kinds of grass. Clover can be good (it does attract honeybees, but I don't know if they bother cows).