You need to have excellent fence to contain pigs. Even then they may try digging under fences "because they feel like it".
Electric wire low on the inside could prevent that, but you HAVE to keep the electric hot ALL THE TIME. This requires
work on your part, checking often so wire is not grounded out to let them escape. Grazing is good for pigs, just that
their nature requires special consideration. You CAN work with piglets, train them to come for food when called or
on a schedule if you can be prompt EVERY DAY in feeding. They are VERY smart and if you miss some feedings, they
will quit coming. This is real helpful if you are hunting for them when out or in the big field, or want to pen them for shipping out.
I would not be doing any communal pasturing with the pigs. They may kill birds or small animals and eat them. They
may not, but really not nice being surprised. Better to keep the pigs apart from the other species if you let them out
on pastuere. I have pretty good fences, so even with small lambs, they stay contained.
We rotationally grazed the paddocks between cows/sheep and horses. Dexter yearling heifer and feeder calf, plus
two lambs, got along well, so were kept together in fields to graze. Horses are large, so we consider it unsafe to
pasture them with other species. Geldings are too playful, would be pestering them all the time, until smaller
animals got hurt. Old mare HATES smaller animals and will charge the fence to get them away. No telling WHAT
she would do without the fence!! Cattle had no horns, so no defenses either, with no places to hide in the pastures.
Horses are on regular worming program, cattle got wormed every 2 months, lambs were wormed once after purchase,
didn't seem to need it again with steady growth and weight gain. Only had lambs for about 4 months, 4-H projects.
All species appear healthy, shiny, very thrifty.
I do think the addition of cattle and lambs grazing have improved the quality of grazing in pastures. I do fertilize fields with
fertilizer from the plant according to soil tests.
Each species seems to have preferances in grazing, often overlapping, but also graze what the other species ignores. This
let me have no problems with overgrazing, even with addition of cattle and lambs. Horses are the main grazers on our limited acres.
The "Chosen Ones" for family interests and if horses did not have enough pasture grazing, other animals would be gone. I do
cattle and lambs first, then horses, then rest the field after mowing. I still mow after the horses are moved out, to keep height
of grass down about 5-6 inches, for constant regrowth and to prevent weeds. Fields get dragged every second mowing, to
break up manure and spread out the cut grass tops, which I think is also helpful in worm prevention, drying up the eggs in
the sun and heat.
No birds except wild ones. This time of year, the finches which look like sparrows, really tear up the horse and cow manure
piles. Fresh manure doesn't last very long while they hunt for undigested grain, leaving the piles broken and scattered a bit.
Rotational grazing, if well managed, can work. Grouping species may not work, or be dangerous for the meeker animals and birds.
We give everyone a good lookin over when we run em through the workin pen. Compared from this summer to last summer, there is a big improvement. Only a couple slightly potbelly lookin older calves (seemingly more of a confirmational issue, looking at thier Mamas) and the few we had to worm a little while ago. And I've not seen any tapeworms either, thank goodness. They put a hurtin on the herd last fall. 
