Våmmen, A Microbial Ecosystem In A Cow

The rumen is responsible for digesting complex plant compounds more easily so that the animal can assimilate them. Therefore, there is a symbiosis between the microbial ecosystem in the rumen and the ruminants.
The rumen, a microbial ecosystem in a cow

Ruminants eat compounds that other species, such as humans, cannot digest. This is due to a wide range of microorganisms in a veritable microbial ecosystem, which is responsible for digesting these nutrients anaerobically (without oxygen) in the rumen, through a process called fermentation.

This process is necessary for the survival of many species of great importance in agriculture, such as cows. Today’s article will discuss what the rumen is and some of the microorganisms involved in this fascinating process.

The rumen, with a microbial ecosystem

Ruminants (cattle, goats, deer and sheep) have a somewhat complex digestive system, formed by four stomach parts:

  1. The heat
  2. The retina
  3. Leaf belly
  4. The tummy tuck

Inside the rumen, thousands of microscopic creatures produce enzymes that help digest plant fibers and cellulose. Therefore, we say that the rumen is a microbial ecosystem where bacteria make up 60% of the microorganism population.

The processes of the rumen

The rumen communicates with the mouth through the esophagus. These are the steps that food follows for digestion:

  1. First , the animals eat plants and these contain cellulose, starch, pectins and other elements that ruminants cannot digest directly, as they do not have the necessary enzymes for this.
  2. The food then passes from the mouth to the rumen, where a microbial ecosystem of various microorganisms converts these complex molecules into simpler molecules such as low molecular weight fatty acids, carbon dioxide and methane.
  3. When these molecules are completely divided into other molecules, which the intestine can absorb, the food returns to the mouth, where it is chewed and swallowed again.
  4. Finally , the semi-digested food goes to the retina and then to the leaf stomach and runny stomach (main stomach) because that is where the digestive process takes place.


These microbial communities produce enzymes with important functions for breaking down carbohydrates (from cellulose, starch and sugar), as well as nitrogen compounds and lipids. This decomposition takes place through a fermentation process.

This process is important for obtaining energy (in the form of adenosine triphosphate), for the growth of the microorganisms themselves and for producing important molecules for the animal, such as glucose. They are also important in compounds that contain nitrogen, which is important for protein synthesis.

The microorganisms themselves produce them inside the rumen, and the animal’s digestive system gets an energy source without having to resort to external elements such as vitamin B or essential amino acids.

microbial ecosystem

The rumen – a symbiotic relationship in an anaerobic environment

We must emphasize that rumen is, as you can see, an example of mutual symbiosis: ruminants provide microbes with a suitable environment for their growth and activity. In return, the microorganisms provide nutrients to values ​​that they would not otherwise be able to assimilate.

In this way, ruminants can eat a diet rich in fiber and low in protein.

This ecosystem in the rumen consists of a wide range of microorganisms. These establish a symbiotic relationship in an environment where there is no oxygen.

This microbiota contains bacteria, archaea, protozoa and fungi. Bacteria are most susceptible to the physicochemical properties of the rumen. Those who dominate this society belong to two different types:

  • Firmicutes – especially those of the genus Butyvibrio, Lachnospira, Succiniclasticum and Ruminococcus
  • Bacteroidetes – Prevotella is the dominant genus here

Archaea make up about 1% of the microbial mass, and eukaryotes can be seen mainly in the form of protozoa. These make up a third of the sum, and there are also some mushrooms.

A microbial ecosystem

Cows need to digest cellulose properly, the main component of the cell walls of plant cells. For this, bacteria that can break down cellulose are essential.

In this case, a pH lower than 5.5 affects the process of fiber degradation, and a temperature of 39 degrees weakens the capacity for bacterial adhesion.

Amylolytic bacteria are also important due to the presence of starch in the diet of cattle and cows that get barley for food.

Lactic acid bacteria metabolize lactic acid and control the accumulation of this substance. In this way, they help keep the pH level in the right range.

Finally, pectin-degrading bacteria also play an important role, as pectin represents 10-20% of the total carbohydrate in the diet of these animals.

Methanogenic arches

The activity of microorganisms is the most important source of greenhouse gases in agriculture. Methane is generated by methanogenic archaea and is obtained as an end product of fermentation. Some consider it an energy loss because it represents 6-10% of the total energy.

This gas contributes to the greenhouse effect when it enters the environment. During methanogenesis, the levels of CO2 and hydrogen in the medium decrease, which is necessary. 80% of methane is due to fermentation of fiber (cellulose) while the remaining 20% ​​is due to the decomposition of manure.


These microbes reduce the risk of acidosis after consuming foods that have a high concentration of easily digestible sugar.

The main function of 90% of the ciliate protozoa is to hydrolyze and ferment cellulose. These ciliates have amylolytic activity through which they produce maltose and glucose.


Some types of cellulolytic fungi produce certain enzymes that can hydrolyze cellulose and xylans. Fungal activity promotes the digestion of cell walls in plant material.

These are especially important when ruminants ingest lignified substrates. For example, Neocallimastix frontalis dissolves the cell walls so that bacteria can access the cellulose without any problems.

young cows

The importance of microbes

As you can see, microorganisms are crucial for the degrading metabolism of food ingested by ruminants. So this is an example of the importance of these unicellular beings in the animal world.

Finally, we must make it clear that this microbiota must stay in good shape to avoid physiological problems in the animal, such as acidosis.

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