Awassi ewe chewing her cud
Ewes eating haylage
Eating creep feed
Let's ruminate on it
- Always chewing
Sheep belong to the ruminant classification of animals. Ruminants
are characterized by their "four" stomachs and "cud-chewing"
behavior. The cud is a food bolus that has been regurgitated.
There are about 150 different domestic and wild ruminant species
including cows, goats, deer, buffalo, bison, giraffe, moose and
elk. Ruminant animals are further classified by the foraging behavior:
grazers, browsers, or intermediate grazers. Grazers, such as cattle,
consume mostly lower quality grasses while browsers such as moose
and mule deer stay in the woods and eat highly nutritious twigs
and shrubs. Intermediats, such as sheep, goats, and white tail
deer, have nutritional requirements midway between grazers and
browsers. Of this group, sheep are more of a grazer, while goats
and deer are browsers.
The primary difference between ruminants and simple-stomach animals
(called monogastrics), such as people, dogs, and pigs is the presense
of a four-compartment stomach. The four parts are the rumen, reticulum,
omasum, and abomasum. Often it's said that ruminants have four
stomachs. In reality, their "stomach" has four parts.
Camelids (llamas and alpacas) are called "pseudo-ruminants"
because they have a three-compartment stomach instead of four
like ruminants. Horses are not ruminants. They have an enlarged
cecum that allows them to digest fibrous materials. Animals of
this type are called "hind-gut fermenters." A rabbit
has a similiar digestive system.
- The rumen digestive system
The rumen occupies a large percentage of the abdominal cavity
of the ruminant. It is a large storage space for food that is
quickly consumed, then later regurgitated, re-chewed, and re-swallowed
in a process called cud-chewing. Rumination or cud chewing occurs
primarily when the animal is resting and not eating. Healthy mature
sheep will chew their cuds for several hours each day.
The rumen is also a large fermentation vat. It contains billions
of microorganisms, including bacteria and protozoa, which allow
ruminants to digest fibrous feeds such as grass, hay, and silage
that other animals cannot efficiently utilize. Fermentation in
the rumen produces enormous quantities of gas that ruminants get
rid of by belching (burping). Anything that interferes with belching
is life-threatening to the ruminant and may result in a condition
called bloat. Mild cases of bloat can usually be successful treated
with an antacid.
The reticulum is closely associated with the rumen. Contents mix
continually between both sections. The reticulum looks like a
"honey comb" in appearance. Relatively litte digestive
activity occurs in the omasum. It is called "many piles"
because it contains many layers of tissue. The abomasum is the
"true" stomach of the ruminant. It has a similar function
as the stomach of a non-ruminant: secretion of enzymes and acids
to break down nutrients.
Source: Sheep Production Handbook, 2002.
| Capacities of digestive tract of
|1.2 to 2.0 quarts
5.0 to 10.0 gallons
0.5 to 1.0 quarts
2.0 to 3.0 gallons
| Small intestines
||2.0 to 2.5 gallons (80 ft)
| Large intestines
||1.5 to 2.0 quarts
- Young ruminants
At birth, the lamb's rumen and reticulum are not yet functional.
As lambs begin to nibble on dry feeds, these two compartments
become innoculated with microorganisms. As the microbes multiply
and begin to digest feed, they stimulate the growth and development
of the rumen and reticulum. The lamb's rumen and reticulum are
usually functional by the time the lamb is 50 to 60 days old.
Because lambs are not born with a functioning rumen, supplemental
feeds such as creep feed, need to be highly digestible. Creep
rations typicaly consist of feedstuffs that have been cracked,
rolled, ground, or pelleted. Creep feeding enhances development
of the rumen in the young lamb.
- Grazers by design
Though ruminants can digest grain (starch), their more natural
diet is forages: grass, weeds, browse, hay, and silage. If too
much grain is consumed at one time by the ruminant, a large amount
of lactic acid is produced in the rumen and the pH of the rumen
drops. This can be a fatal condition to the ruminant animal. Grain
must be introduced slowly to the diet of ruminants to give the
rumen time to adjust.
- Not too much grain
Sheep "love" the taste of grain. It's like "candy"
to them. They will overeat if grain consumption is not regulated.
If grain is slowly introduced to the ruminant's diet, grain can
be supplemented and in some cases replace some of the forage in
the diet. Whole grain is better for sheep because it requires
them to do their own grinding of the grain. Digestive upsets are
less common with whole grain as compared to processed grains (ground,
rolled, or cracked).
Some forage should always be fed to ruminants to keep their
rumens functioning properly and to keep them content.
article The truth about feeding grain to sheep and goats=>
- Greenhouse gases
One of the global impacts of ruminant livestock production is
that when ruminants belch, they produce methane, one of the greenhouse
gases. A small amount of methane is also produced by manure. Scientists
are currently study ways to reduce methane production from ruminant
livestock. For example, it is known that livestock fed certain
plants produce less methane. Australian scientists are testing
a vaccine to reduce methan production. "Fart" taxes
have been proposed to help fund the research. They have not been
Greenhouse cases are believed to contribute to global warming.
By far, the largest source of greenhouse gases is fossil fuels.
<== WHAT SHEEP EAT