A good definition of a ‘weed’ is simply a plant growing where it’s not wanted. Oftentimes, while the ‘weed’ may be ugly and unwanted, it’s a powerhouse of nutritious food/feed source of man or beast. At least at certain times of growth.
Thankfully, cattle, sheep, or other livestock can take full advantage of many weeds and can turn them into meat or milk and I don’t have to mow them, chemically kill them, or stress that they are there. There are times i do have to intervene, but proper grazing pressure can sure eliminate a lot of work for me.
Ironweed, multiflora rose, foxtail, honey locust, mare’s tail, ragweed, even cocklebur (though to a lesser extent) are readily eaten in whole or in part by cows. Those are only a few of the weeds they eat but those listed are some of the most egregious to a producer because if allowed to proliferate, they can shade out better quality grasses and forbes.
The huge mess I have on the farmed ground is 90% weeds on the acreage i allowed to be organically row cropped for 4 years to soybeans. I had to disk it twice and harrow it to smooth it out from the ridged till condition in which it had been left, so another year of open soil provided a perfect seed bed for weeds. There is little doubt that there is plenty of grass seeds in the soil bank, but it may take several years of strategic grazing pressure to bring it back to its pasture. I can’t say ‘former glory’, because before it was about 90% toxic endophyte fescue and that wasn’t good either.
Both calves and cows will obliterate thorny honey locust trees when the leaves are tasty and perhaps when they are the most nutritious.