THE RUMEN IS A FERMENTER…
How can a cow digest cornstalks and grass?
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They are ruminants - rumination means "to chew cud"
At birth, the rumen is not fully developed
Very early in life, the rumen is inoculated with bacteria through feed and interanimal contact
Anaerobic bacteria very similar to those found in the rumen are present in manure and soil
Despite bacterial sensitivity to oxygen and low temperature, some will be transferred via saliva and
feed and pass through the digestive track
This bacteria is needed to help ruminants digest the foods they eat
Between the mouth and animal cell:
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Billions of microbes
Buffered with saliva
Anaerobic
Temperature-controlled
Continuous mixing
Grinding
Product Removal
Continuous supply of Nutrient
A Dairy cow will
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Weigh 1,400 pounds
Drink 25+ gallons of water daily
Consume 50 pounds of dry feed
Producer 40 gallons of saliva
Ruminate 10 to 12 Hours Daily
PROPS: Tanned rumen, rumen content sample, feeds, 2 posters - one showing the rumen
with velcro pieces and one with animals where students guess if the animals are
ruminants or not.
Ruminant Nutrition
Ruminants are able to eat forages. People have one stomach, so we are not called
ruminants. Pigs are not ruminants, because they only have one stomach. Horses, cattle,
goats and deer can eat forages because they can process it in their stomachs and process
the forages into something we can eat, such as milk or meat.
Many people think that a cow has four stomachs, but actually a cow has one stomach
with four compartments. This is an actual, preserved cow stomach. It is from a heifer
that is about a year old – so this stomach is only about half the size of a full grown one!
A full grown stomach will hold 50-60 gallons of food.
The four compartments of a cow’s stomach are: the abomasum, omasum, rumen, and
reticulum. Cows are called ruminants because of one of the largest portion of their
stomach – the rumen.
The abomasum is similar to a human stomach. It digests and absorbs the food into the
blood stream. It is the main digestion and absorption compartment of the stomach.
The bulk of the cow’s stomach is the rumen. The rumen is constantly mixing, turning,
and digesting of the food the cow has eaten. The inside of the rumen is lined with
fingerlike structures called papilla. The papilla help increase digestion by moving the
food around inside the rumen.
The omasum is made up of many folds. It does much of the digestion and takes a log of
the water out of the food.
The reticulum looks much like a honeycomb. The reticulum is often called the
honeycomb stomach or the hardware stomach. If a cow eats something it cannot digest,
such as a bolt or nut that has fallen off equipment used to care for the cattle with, it will
fall to the reticulum. A magnet is placed in the reticulum to hold such hardware all in
one place and to prevent it from moving any further in the cow’s body. Cows will eat
such items at some point.
There are two types of food that cattle eat: forages and concentrates. All of the feeds
that cattle eat fall into these two categories. Alfalfa hay is a forage. Alfalfa is cut, dried
and baled. It has a great deal of protein and energy that people cannot digest, but cows
can.
Alfalfa silage is a forage cows eat. The whole alfalfa plant is harvested when it is wet. It
is chopped up and packed in either a silo or very large bag. It ferments and stays in this
state because oxygen cannot get to it in the silo or bag. So it does not mold either. Corn
silage is made in this same way. The entire corn plant is chopped up, stored in the silo
and turns brown in color.
Cows also eat concentrates. A typical concentrate mix might consist of corn and soybean
meal, soybean hulls, calcium, Vitamins A, D and E, phosphorus, and extra fat for energy
– the things that cattle need for a nutritious diet.
Another food cattle might eat is cottonseed. When the cotton is ginned, the seed is left.
Cotton seeds are much like other legume seeds, such as soybeans or peanuts. The seeds
contain oil which is high in fat, high in energy and high in protein. The cows eat about 4
pounds of cotton seeds per day. The cotton seeds act much like a concentrate because
they contain a lot of energy. And they act like a forage because they have a lot of fiber.
How many pounds of feed does a cow eat each day? A cow will eat approximately 100
pounds of food each day. This includes 30 pounds of concentrate and 70 pounds of
forages.
Have you ever seen a cow chew its cud? What does this mean? The cow regurgitates
food out of the rumen. The rumen is squeezing and digesting. The cow chews the food
again and swallows it again – aiding in the digestion by adding saliva that helps break it
down.
(If available - show the students a sample of the contents of a cow’s rumen.)
The cow has eaten the feed, chewed it up and it is in the rumen. It’s wet because the cow
has added saliva to it.
How do you get a food sample from a cow’s stomach? Some cows have a rumen fistula.
A rumen fistula is a hole in the cow’s side and rumen. The two are attached together and
a plug is put into the hole so that researchers can reach in and get feed samples from the
cow’s stomach.
The fistula is used for research. The rate of digestion, the rate of food passage and how
much feed the cows can use can be measured using the fistula.
For instance, how do we know that 4 pounds of cotton seed is best for the cows?
Different levels of cotton seed are given to the cows in their diets. The rate of passage
and digestion are measure by using a little bag on a string in the rumen. The bags are
constantly put in at different increments – such as every 12 hours and then are checked
two days later to the differences in digestion.
The fistula is like any surgery – such as having your appendix taken out or when you
break your arm. The cow is given anesthetics and it takes about two weeks to heal. If
you peeled back the opening, you would see a layer or skin and muscle. The fistula
doesn’t affect the life of the cow in any way.
Cows basically eat, sleep, and make milk. They chew cud 10 – 14 hours per day and eat
approximately 4- 5 hours per day. They spend about 1 – 2 hours waiting to be milked
and actually being milked. And the rest the remainder of the time.