Problems with a change in ruminant's diet

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Most grazing animals used for food and fibre production on farms are ruminants. But what, exactly, does the term "ruminant" mean and why is it important?

A ruminant is, very simply, an animal that has a rumen - an animal such as a cow, a sheep or a goat. In these animals, the rumen is the second of four "stomachs" that help the ruminant digest grass.

The first of the four stomachs is called the reticulum, commonly known as the "honeycomb", the second is called the rumen ("paunch"), the third the omasum ("bible") and the fourth the abomasum. This fourth stomach is similar to the human stomach.

A camelid - that is, a llama, alpaca or camel - has a similar type of arrangement, but with a different number of stomachs.

The common name for each stomach refers to what it looks like.

The reticulum, or honeycomb, looks very similar to honeycomb, with a lot of polygonal-shaped folds lining it.

The rumen, or paunch, derives its name from the fact that it takes up most of the space in the belly in an adult animal.

The third stomach, or bible, gets its name from the folds in it that look like a lot of pages, similar to the bible.

The fourth stomach is generally just called the stomach, as it is very similar in function to a human stomach.

Much of the material that a ruminant eats is indigestible for a human, as we can't break down cellulose from plant leaves efficiently.

The first three stomachs of ruminants are essentially a giant mixing vat, designed to break down plant fibre so that the ruminant can then digest and absorb it in its stomach and intestine.

Tiny micro-organisms in the rumen are vital to the process of breaking down plant material into digestible material. These micro-organisms have a symbiotic relationship with the ruminant - both need each other to survive.

Plant material is physically broken up by continual re-chewing of food by regurgitation - "chewing the cud" - along with the mixing of food in the rumen and reticulum.

When ruminants are not grazing they can often be found camping and chewing the cud. Once grass is small enough it will pass through into the fourth stomach.

The fourth stomach is acidic, similar to that of a human stomach. The first three stomachs, however, have a neutral pH.
One of the most common causes of problems in ruminants is a sudden change in the rumen acidity, leading to a condition known as acidosis.

This is caused by eating a large amount of starch, usually from cereal grains such as wheat and barley, and can be a problem when feeding animals in droughts like the one we are going through.

Early signs of acidosis include diarrhoea, lethargy and general abdominal pain. If an animal receives enough grain, acidosis can lead to severe sickness or even death.

Acidosis severely damages the numbers of helpful micro-organisms in the rumen. So, if you are going to feed a ruminant grain, you need to let both the cow and the micro-organisms adjust to the grain over three to four weeks.

If any animals accidentally get access to large quantities of grain, they should be removed from grain immediately and be given access to roughage, such as hay.

Drenching with bicarbonate may also be helpful, but it is best to consult your veterinarian for the best treatment as soon as you know the animal has eaten too much grain and is showing early signs of acidosis.

Once it eventually does rain, it is as important to let a ruminant adapt to an increase in green feed as it is to let the animal adapt to grain feeding.

If you are currently feeding your cattle or sheep, you should continue feeding while getting stock used to new green feed.

This time is needed for the microorganisms in the gut to adapt.

A gradual transition between feed types will allow animals to utilise the new feed better and avoid any rumen upsets.

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