If you have some pasture you can put grazers on it. If it is not regularly cut (to make hay or silage) or grazed, it will naturalize. Rough weeds, nettles, brambles... and later birch trees and other trees take the grounds. Nice too, of course.

dierenmIf you want to put animals on, then how many can be on the plot? How many m2 per animal do you need?
That's hard to say exactly. It is not a theoretical mathematical problem.

Is the soil fertile? Sand, loam or clay? Dry or wet? Rich in humus? Regular fertilization?
Are there (many) trees? Of which vegetation consists the grasses and herbs?

One animal is not the other. There are different varieties, shapes and sizes.
The animals are pregnant? Do they have/make offspring?
Are they additionally foddered? How much and what?
They are (often) milked?

Also important is whether you want to harvest winter feed hay from the same area. Or do you get or buy it elsewhere?

Make at least there is shelter from sun, cold and rain, and that there is always enough healthy drinking water and that the fence is suitable and decent.

It's usually a good idea to divide a parcel into several plots. After haying you can still let the remains and edges to graze, and then introduce animals for alternate grazing. And after grazing you can leave a lot to rest for 3 weeks. That time, the grass will need to recover.

For horses is usually count on 3 horses per hectare (= 10.000m2), so definitely 3.000 m2 per horse.
A pony also needs 1.000 m2.

The organic livestock holds up one cow on half a ha of land, but rather one cow on approximately 10,000 m2 of pasture. A lactating cow can eat up to 20 tonnes of grass per year. In the States they're counting 1.5 to 2.5 acres per head in the grass season (May-October) x 4.017m2 is 6,000 to 10,000 m2.
A plot would actually, depending on size and grazing, no longer than four days be grazed. The grass should be sufficiently grown, so be more than hand high.
Every four days you need per cow eighty to one hundred square meters of grassland.
In summer this is though 90 kilos of fresh grass per day! For a good milk she gets there still concentrate extra.

in1m2soilIn countries with lots of space and a favorable climate grass can continue to grow, and animals may continue to eat green grass all year round. At our latitude is 100% grass dependant cattle year round not feasible.
It's too cold with too little sunlight (photosynthesis) to grow grass longer than 6 months. And there is a lack of space with 500 people per km2. For a grass-fed ox under ideal circumstances, we do not have, is needed approximately 7000 m2.

On 1 ha (10,000 m2) you can –depending on the grass- graze 10 to 15 sheep (with lambs) the whole year, so including winter hay.
That's about 700 to 1,000 square meters per sheep. Without hay is required approximately 5,000 m2.
Also 15 to 20 ewes are possible provided supplementary feed and change plot (rotational grazing) every 3 weeks.
Sheep will eat about 4 m2 grass per day per sheep.

A (milk) goat eats less, but also eats just about all herbs, and bark! And needs a higher and denser fence.

For grazing is sometimes said: 1 cow = 7 sheep.
My geese each year cut about 300m2 short per goose.

For a chicken you need at least 4 m2 mainly green covered outdoor space per hen.

Rather start with too few animals, than with too little food.
Country that is not used a time will yield more the first year. Depending on the weather there may be much difference between every year. If too much grass, you can still add animals later. If the fence permits you can e.g. put a sheep at the horses. They gnaw still picking grass (around manure) that the horses do not nibble.

How much hay you can harvest per hectare also depends on the factors mentioned above.
If it is compressed in (handsome) packets (small square bales) they can also vary in weight yet. Usually a bale will be 18 to 20 kilograms. If the grass is mowed knee-high you should obtain for sure 120 packs / ha.

Ragwort is poisonous. Also hay with remnants of ragwort are not suitable as horse and cattle feed.