How long does the grass have to be for cows to be able to eat it?

Answer 1

Cows will eat about 2-2.5% of their body weight in dry matter (take all the water out) grass if that is all that they consume. Lets use an example: 1000 lb cow x 2.5% = 25 lbs of Dry Matter 25 lbs of dry matter / 15% dry matter in grass = 167 lbs of grass per day Grass is about 85% water - thus use 100-85=15% There are several factors that affect this amount. As you can see by the equation, the biggest factor affecting intake is body weight. Also how much moisture is in the feed. Animals eat dry matter, water does not count.

Answer 2

Most grazing schools and graziers recommend that grass be at least 8 to 10 inches in height before you put your cows on pasture to graze. This isn't so much about "for cows to be able to eat it," it's more about the health of your grass and what is the best height and stage of your grass to be for cows to graze without adversely affecting the grass sward's ability to regrow again and how vigorous it is during the rest period and into the next grazing period.

The thing is, cows can graze grass at any height, be it an inch off the ground or 6 feet in height. What's most important is that you graze your cows at a time when the grass can handle it; when it's not going to be harmful for your grass. If you graze too early, you could kill the grass. The reason for this is that, during growth periods, grass is relying on the energy stores in its roots to shoot up some new leaves in the spring. It will rely on this store until the grass plant has adequate leaf area to begin the process of photosynthesis. A grass plant will begin photosynthesis as soon as it has two or three leaves out, but it's still relying on the root stores to grow a bit more. Also, at this stage the grass plant has very little nutritional value to it, only water. But as it grows more and more, nutritional value increases. Only until that grass plant has at least 5 or 6 leaves out is it no longer using its root stores, but instead using the external environment to grow. It's during this time that cows can be allowed to graze and actually get a satisfactory to excellent level of nutrition from the grass, depending on the health and fertility of the soil.

Now if you graze too late, you won't have as much nutrients in the grass for your cattle. The grass will also get too far ahead of your animals, and start to head out. When grass starts to head out, it no longer wants to put its resources into growing leaves, but instead growing the inflorescence or grass-head from flowering stage to maturity. For some grass species, when it gets into this stage, palatability decreases, making cattle get more picky and less eager to eat this grass. Some grass species, however, like most native grasses, actually benefit if grazed past maturity, since they tend to decrease in population if grazed during their growth period versus when they go into dormancy.

So when grazing, be careful about timing when you let your cattle out to when and how fast your grass grows. Graze and rotate pastures quickly when grass is growing, but slow it down when the grass is starting to head out or go into dormancy.

Answer 3

Cows have a complex stomach which allows for more efficient break-down of tough and coarse plant matter that they can use for their metabolic, reproductive, growing and maintenance needs. Though it is true that cows do very poorly on poor-quality forage, and are best fed a good to excellent quality forage, they are still able to use and grow on that forage better than humans can who would try to eat the same things. Cows and calves gain on good grass: most humans would starve to death on it.

See related questions for more.

Answer 4

Grass takes around 24 t0 36 hours to digest. Basically, the greater the moisture content of the feed (and the higher the quality), the faster the digestion rate. In other words, grass will go through a cow's system faster than hay will.

Answer 5

Only 12 hours. That's why most cows are milked once every 12 hours.

Answer 6

Only around 12 to 24 hours, depending on what was eaten. Sometimes it's much shorter than that.