They most likely don't. But they do eat dead grass occasionally...
One cow needs between 25 and 50 gallons of water per day. The total amount of water for a herd of cows depends on how big that herd is, what stage of life they are at (lactation or gestation), diet, etc.
They eat legumes, like alfalfa, laspedenza, trefoil, cicer milkvetch and clover, but these are primarily found on pasture or in hay. All other feeds fed to cattle, from grain to silage to hay, is all made from grasses. Ninety-eight percent of grains fed to cattle come from species of grass that has been modified to produce high volumes of seeds. These grasses are barley, wheat, corn, rye, triticale, sorghum and millet, to name a few. Even though most people believe that the feeding of grain to cattle is not feeding them grass because they are being fed the seeds portion of the plant and not the vegetative portion, these grains still come from grasses.
So, ultimately, the answer is pretty well no.
Free range meat are animals that are not kept in cages or small pens, they are able to roam freely, they also may have a free choice to grains or grasses.
There are too many variables at stake here to be able to fully answer this question. It all depends in the size of the cow, what she is or has been fed, her maintenance and thus lactation and reproductive requirements, the quality of the feed or pasture she is fed or eating, what condition she is in (needs to stay at, lose or gain), and moisture content of the feed.
We can, however, provide an average amount that a cow should consume in an entire year, not counting for the variables expressed above. Let's say we have a 1000 lb cow that eats 2% of her bodyweight in dry matter feed per day. That means she is eating around 20 pounds of dry matter per day. So for an entire year (365 days) that calculates out to 7300 pounds, which means she is expected to consume around 3.3 tons of feed a year on a dry-matter basis. On an as-fed basis, that number could change from anywhere around 4 tons to 12 tons or more. This is because a cow will consume more feed if it is higher moisture and better quality, and will eat more if she's thin and needs to compensate for losses sustained over time, and/or is experience some level of cold stress that is causing her to eat more to meet her energy or nutrient needs. Lactating cows also tend to eat more than dry cows, and pregnant cows will eat more than open (non-pregnant) cows. Finally, some cows are more "feed efficient" than others and despite being in the same lactational or reproductive stage as the other, one may eat less feed to maintain the same condition (or even increase it) than another cow.
A rule of thumb to know is that a cow will not consume the same amount of feed over an entire year. No cow consumes the same amount of feed as another cow, not even on a dry-matter (all water removed) basis.