The obvious answer to this seemingly mindless, extremely easy-to-answer question is...
In all it's various forms.
But, of course, that's only part of the story.
Sure cows and cattle eat grass because that's what they're built to eat. They are ruminant animals, meaning they have three fore-stomachs plus the true stomach that is structurally adapted to a diet of fibrous plant material.
Plus they have millions of microflora to help them break down that plant material into usable nutrients.
A quick Google search will give you several sites that tell you the three primary feeds that cattle eat:
A fourth "feed" that cattle will "harvest" themselves is pasture forage (also called fodder).
There is also a fifth feed that takes on a minor precedent known as "by-product."
Now, the three four five primary feeds are largely of grasses or derived from grasses.
Hay is cut and sun-dried forage that is gathered up into bales (NOT "bails"). Plants used for hay are primarily perennial grasses that come up to be harvested year after year without any need to cultivate and re-seed (usually).
Grain is that of seeds from domesticated grasses such as corn, wheat, barley, rye, and oats.
Silage is fermented feed that comes as chopped forage that is put into a pile, squished down to get as much air (oxygen) out as possible, then left to basically "pickle" or ferment for a few weeks. Baleage is another form of silage that is not chopped, but rather gathered up into bales as wet fodder, then wrapped up in plastic as individual bales or in a long tube. Most silage consists of domestic grasses like barley, corn, or oats; it can also be made up of grasses that could be used for hay.
By-products are waste material from processing grains or crop seeds into various products for human use or consumption, such as beer, biofuel (including ethanol), baked goods, or vegetable/cooking oil. While domestic grasses make up a large part of this production, other crops like sunflowers, canola, and soybeans are also extensively used. By-products may also include waste from supermarkets (such as waste vegetables, starches (potatoes, carrots, etc.), and fruits) due to grading and aesthetic concerns, that can be fed to livestock in limited quantities.
I purposefully did not include animal by-products as a part of the by-product list for cattle because such feeds are prohibited from being fed due to Mad Cow Disease concerns (also known as Bovine Spongiform Encephalopathy.)
Oh, but wait! I forgot to add two more items to what cattle are fed! I'll bet you didn't know that cattle also eat:
Greenfeed is treated just like hay, except that the forage component of that hay is not your typical perennial grasses as a "hay stand." Instead, this is usually made up of annual domestic grasses primarily of oats and/or barley that are cut green, dried in the sun, and baled up. Another type of greenfeed is "yellowfeed" which is a crop harvested for feed after being desiccated with a herbicide, usually glyphosate. Yellowfeed can also be a cereal crop that has gone to maturity, and is cut and baled up for feed. (Farmers have been known to also bale up non-cereals like peas or canola to feed to cattle.)
Straw is what's left over and gathered up into bales after a cereal crop is harvested for its seed (grain).
What are Cows and Cattle Fed?
What feeds are fed to cattle depends on how they are raised. Dairy cattle in confinement will be fed a variety of feeds in what's called a TMR (total mixed ration). It ensures that they get all their nutrients and types of feeds they should have for healthy rumen function and milk production. A TMR includes hay, silage, grain, and maybe some kind of by-product like soybean meal or canola meal.
I should really answer this in an other post on "How do Cows Eat" but what's funny about dairy cows being fed a TMR is that they're not stupid or dumb about carefully selecting out their "desert" first (the grains) and leaving the "vegetables" (the hay component) behind until they really have to eat it. That's why I used the words "they should have" because the human component behind the dairy-cow ration balancing expect the cows to eat everything in equal portions, when they really don't!
Beef cattle are primarily fed hay with some grain and/or silage. At least, those cattle or cows that are still raised traditionally (kept in pens during the winter, out on pasture in the summer). Cattle being finished in the feedlot are primarily on silage, with some hay and grain, then progressively fed more and more grain and silage (with a little hay) by the time they reach the end of their short lifespan prior to slaughter.
Here's where the waters get pretty cloudy. The aforementioned methods of feeding beef cattle have been practiced for many decades. But now, farmers and ranchers are taking winter feeding into more winter grazing, where hay is either being fed out in the field, or cereals are cut into swaths, but not gathered up into bales. Instead, electric fencing is used to get those cattle to eat those swaths instead.
Producers in more southern locations where winters are mild or non-existent can graze their cattle on pasture 365 days of the year. (Many cannot due to not understanding proper grazing practices of rest and rotation.)
I mention greenfeed and straw because beef cattle will be fed those feeds as well. The kicker with these is that the straw needs to be fed along with grain because a cow cannot handle an extremely high-fibre, poor protein feed source, and greenfeed needs to be fed along with a high-calcium/magnesium mineral, unless it is mixed with a hay that has lots of legumes in it (like alfalfa).
The other fun part of this question is that, continuing on with grazing, is that cattle can be grazed in annual crops that contain a variety of species that are primarily legumes, grasses, and broad-leafs (like kale, turnips, sunflowers, phacelia, flax, radish, etc.). A few producers are able to finish their cattle on this stuff, and get those cattle about as fat and sassy on that standing forage as those cattle being finished in the decades-traditional feedlot.
What do Cows Eat Other than Grass??
Legumes. Legumes make up a pretty hefty portion of a bovine's diet. Legumes are primarily found in hay, as well as pasture. Cattle will also readily eat other non-leguminous broad-leaves (or "forbs") if they find the plants particularly palatable (there's an alliteration for you!)
Did you know that grass makes up 95% of a bovine's diet? That means 5% of the diet is legumes, forbs, and some trees and shrubs, if they come across them.
There are quite a few different types of legumes that cows will eat, including:
Other non-legume forbs that cows will eat include:
It's not uncommon for cows to be sometimes browsing on trees and shrubs, if available, when they feel the need to. Like us humans, cattle generally do like a wide variety of foods to eat for reasons beyond the fact that they just taste good.
Cows Eat Grass on Pasture. Right?
Partly. Cows will also eat legumes, as mentioned already, and other broad-leaf plants. A pasture that has a good legume component means that those cattle will get a lot of nutritional benefit from those plants. Actually, let me put it another way: It's not just about the legume component. If a pasture has a high biodiversity of a variety of plant species, not just grasses and legumes, that means there's plenty for the animals to eat... as well as to feed the other and much less noticeable "livestock" living just beneath the soil surface.
Pasture for cattle isn't limited to perennial vegetation. Cattle can also utilize cropland as part of a crop rotation scheme where some annuals or biennials (such as fall rye, winter wheat, or an annual cocktail mixture) are seeded to provide temporary pasture in the summer and even into the fall, particularly if there's an anticipation that perennial pasture may be short, or if a farmer wants to stockpile the perennial pasture for winter or early-spring grazing. Livestock are also incredibly versatile (and the farmers themselves) in that they can also be grazed on cropland during the fall or winter on crop residue, on swaths, or even on crops that missed being harvested; cattle are also great at utilizing a crop that was lost from hail damage.
(This is why I strongly believe the land-use argument for meat-eating versus a plant-based diet is a non-issue. That will be an upcoming blog post, stay tuned!)
When cattle are pastured in any plant stand, they will select what is palatable to them, typically by taste and by previous knowledge they've gained from either trial and error or from what their mothers have taught them. They can be quite selective, wrapping their tongues around and tearing off the plants they want to eat, and spitting out (cows have a funny way of spitting things out unlike us humans) what doesn't taste right. They know what plants they should ignore, and will eat around those particulars leaving them standing in the pasture--unless it's in a mob-grazing system where such plants aren't likely to be standing untouched for very long. As Greg Judy has put it, livestock actually have five mouths, not one: There's the one that does the tearing, and the other four that do the "eating" via trampling.
Certain weeds will be eaten by cattle if they are trained to, such as Canada thistle. If there are dandelions in a pasture, they will eat those with relish. And when grazed in a large group where competition between animals is prevalent, they may also eat those weeds that normally, in a continuous set-stock grazing system, they would sooner avoid; or, those weeds will be trampled down and pooped on, turning them into plant litter and organic matter.
So, Cows Eat More than Just Grass. Got It!!
Yes indeed. The take-away message here is that cattle will eat more than grass, not exactly because they are forced to, but because they choose to, and can.
In the end, they are herbivorous ruminant animals who will eat more than just grass for reasons including taste, and a craving for something (minerals, vitamins) lacking in their diet. Plant choices are also due to what they have learned from their mothers at a young age, or through trial and error.
Range Nerd, Forage & Grazing Fanatic and a Bovine Enthusiast. A love for farming, and for the soil.
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