The ecosystem of pasture cattle is, the soil and water and sun produce grass, the cattle eat the grass, then the cattle get taken away and shipped to all parts of the world and eaten by humans. It is a one-way extraction of resources, except for the manure and urine, which return to the soil, but the land does get depleted over time. Also the soil gets compacted. And cattle are very dangerous and scarey to rabbits, lizards and other mid-to large sized mammals such as deer, which avoid interacting with them. It is possible to manage cattle in ways that do not require remedial medication against flies, ticks, and all sorts of intestital parasites, but the cheaper and easier way is to dose the animals with abamectin, etc. Termite mounds are abundant in this area, so are ant hills, and insecticides are used to destroy them, just to increase the area that grass can grow. Herbicides are used to kill plants that are not grass. Again, this could be done with labor, but the faster way is dousing with herbicides, roundup being the least toxic of the choices. Pasture is still agriculture, you are growing grass.
Pasture raising is lower density than confinement but it is higher than (I imagine) would be natural. Animals get sick, their hooves crack, they fight and get wouned, they fall in holes, or try to jump a fence, calves are very susceptible to injury. I know the way my parents raised was not very well managed, just like if you have a backyard full of cats, and you dont really care about them, when they show signs of illness, you just shoot them up with antibiotics because it is cheaper than calling a vet, or good prevention or letting them die.
I agree with all of Brimstone salads responses to Carnap, and just wanted to add the above.
@Dsalles' family literally runs a grass feeding operation.
Brimstone is right, my stepfather and brothers are continuing with my late mothers grass-fed cattle production, in Brazil, but I, after some legal battles, have separated my part and am getting out of cattle and transitioning to organic agriculture.