Eric:

The common pasture tree is pecan. Many trees never get big enough to stand cattle rubbing. Apple and pear probably would but not for many years.

If you have deep soil, pecans would be a good choice. Mulberry seems like it might be a low-care choice. Grafted varieties. They would attract birds. Might self-sow.

My grandparents let cows graze in a small apple orchard after the orchard was already established. Pears might be more tolerant of the heavier soils often found in pastureland. There are cattle grazing in an old almond orchard near us.

The jujube variety I have is thornless, but the suckers have short thorns. Lots of them. Curved and sharp. I don't know if they would grow fast enough to be good choices for you. Don't know if they might hurt livestock. I don't know if the seeds would be toxic. Might want to check.

One reason pecans are favored is that their shade is light enough to support pasture beneath and between them even when planted orchard fashion and not just as a scattering. Cattle hanging around beneath pears or apples might possibly kill them by overfertilization and induced fireblight, but I'm just speculating. Jujubes don't give much shade. Mulberries would be quick, once you got them above deer-nibblng height. Personally, I'd try a few of each at first. And persimmons.

There is no such thing as a tree that can withstand livestock in a pasture situation. You will have to fence the trunk and a few feet of the root zone.

If you want a crop, I suggest pecans, full size apples, or probably in your area, you could grow a fig tree.

You might as well do a mixture. Maybe add a mulberry tree if the mess doesn't bother you and you don't mind all the birds it attracts.

Bosc pears grow tall and really fast, if it isn't too warm for them in your zone.

Thanks for all the thoughts and suggestions.
I don't really know how hard cattle or other livestock would be on mature trees in other regions and management systems, but I know that lots of trees can survive the pressures of livestock in my system: in my pasture rotations (mostly along the edges but within the paddocks) I currently have a sycamore, pines, alders, red oaks, black walnuts, red cedars, and tulip-poplars, and they've all done fine. Tulip-poplars and red cedars seem like they might be harder to get through the earlier years but not too hard.
I hadn't initially thought pecans for a few reasons. I'd be interested in hearing your thoughts on these issues. First, pecans are such a large tree that they'd give me more shade than I'd need for the animals, and I don't think I want that extra competition with the grass. Secondly, pecans seem like awfully small nuts to try to find in pasture-type grass. Would bush hogging be sufficient to get the grass down low enough to find most of the nuts? Thirdly, what about manure contamination? I would want the shade most of all in the summer. Could I let manure fall under the tree all summer and then safely harvest the nuts immediately afterwards? On the one hand, I figure I need tall trees to grow above the reach of the livestock, which would make a crop that fell to the ground practical, but on the other hand, there are the issues of manure and finding the crop in the grass, so that leads me to think relying on ladders might be a good compromise.
Any suggestions for a particular mulberry cultivar? Some varieties seem to have more tree-like form than others. I think I'd want a tree with a trunk that went straight up beyond where cattle could reach and then formed its canopy.
ORwoods, you mentioned figs. I do have some figs near my barn, and I've noticed when I've had animals on leads walking past my figs (or when they've gotten out of the fence) that they've never seemed interested in the fig bush. Are there specific varieties of figs that could better be trained to more tree-like form (as with the mulberry)?
What about kaki persimmons? Would they even get big enough? Could I get extra height/trunk by grafting a kaki 6 foot high on a D.v. rootstock? Could that work?

It would have to be a tree that gets tall fast, and can withstand the surface high nitrogen. I think chestnuts (at least 2 for pollination) fit the bill, and their tap roots should be more resistant than a tree with predominantly surface roots. Chestnuts are eaten roasted, which eliminates concerns about bacterial contamination, and their burrs (easily removable) are both more visible and will defend the nuts from cattle and manure. I concur about heavy fencing. Persimmons and figs are too small IMHO.

I think nuts would take too long to crop.
Mulberries are the perfect choice, morus nigra if they will grow for you, they won't self-seed and they are the most delicious fruit there is.

Carla in Sac

cuzn floyd,
Anything you plant is gonna have to have some protection for a number of years until they gain enough stature to keep livestock from demolishing them.

I'm planting a mix of pecans, black walnuts, and some oaks along the dividing fences in my creekbottom field(formerly a corn/soybean crop field), to provide shade to the cattle.
From previous experience, I will tell you that you've GOT to provide protection to those trees for quite a number of years. Once they get to about 6" dbh, they're probably able to withstand cattle.
Horses, on the other hand, will stand there and eat the bark off of any tree they can get to, so you've got to put some sort of fence around them so that they can never reach the tree - though I've seen big trees on some farms in Lexington KY that just had 2x4 woven wire wrapped around the trunk up to about 8-10 ft to keep the hayburners from girdling them. They originated on the treeless plains, and try their d@mndest to recreate that scene.

I have a couple of pecans of bearing age in one of my pastures. Cows will eat the pecans as fast as they drop. So will deer, but a few passing deer won't get as much of the crop as will a herd of cows standing around under one or two trees, eating nuts as quickly as they drop.
For best harvesting, you'd probably need to mow fairly short underneath the trees just before nut drop.

Mulberries might well do a good job - and they're certainly fast-growing. Have seen some big old standard apple trees that met the criterion of a shade tree - had one in the middle of the hayfield on the farm I grew up on.
I've left a few 'volunteer' Osage Orange trees to grow up here and there in my pastures - and might plant a few more along these fences; once they get above the height where cows/horses will be able to reach, I intend to graft Che (Cudrania) onto the top of the OO understock.

Grew up on a dairy in PA...I would caution against apples as we have lost calves and heifers due to choking. If it was me, I would go with mulberries but you will have to protect the trunk.

Ah, bamboo - good point.
As a veterinarian, I have seen cattle 'choked' on apples and the fruits of Osage Orange. Not an experience I want to go through again, and certainly not with my own herd.