Cellulose makes up a significant part of the plant cell wall. In fact, cellulose content is approximately 30 to 50% of dry matter. Cows satisfy their dietary requirements through the consumption of plant matter hence the need to be able to breakdown cellulose for nutrients absorption. As such, since cows depend on plant material for primary feedstuff, cows can digest cellulose. In fact, their digestive systems are design in such a way that allows for efficient breakdown of cellulose. Cellulose basically comprises subunits bound together by covalent bonds. These subunits are the simple glucose sugar linked by a very specific bond that makes digestion a difficult task, particularly for humans. Unlike humans, cows can digest cellulose. This is because their rumen contains organisms that allows for tits breakdown into a form from which they can be extracted. Without these micro-organisms, it would not be possible for cows to digest cellulose.
Digestion of Cellulose
Humans lack enzymes necessary for the digestion of cellulose hence their inability to feed on raw plant material. Cows can digest cellulose despite lack of cellulose digestive enzyme. As previously noted, this is owed to the presence of microbes that make cellulose digestion possible. The stomach of a cow consists of four separate chambers which all play an important role in the digestion of cellulose. When a cow consumes plant material, it moves down a canal that connects the throat to the stomach. This canal is known as the oesophagus; it is basically responsible for the transportation of all materials from the mouth until reaching the stomach where digestion takes place. The consumed plant matter is then partly digested in the first chamber after which it is further transported to the second chamber which is termed reticulum. It is in this part of the stomach where plant material is turned into cuds which are basically chunks. Note that due to this digestive process, cows can digest cellulose.
The microbes responsible for the digestion of cellulose are found in the rumen, which is the first chamber. A process known as regurgitation then takes places. Following the breakdown of food into smaller manageable particles, the cud is pushed back up into the mouth where it if further broken down through chewing. The chewed cud is swallowed once more for the completion of the digestive process. The abomasum is basically the equivalent of the human stomach. As such, plant material is broken down again and passed to the small and large intestines where nutrient absorption takes place prior to excretion of waste. Humans, similarly to other monogastric animals have stomachs with only a single chamber hence digest feed differently to ruminants. As previously noted, it is this difference in the digestive systems that means cows can digest cellulose quite easily. Note that the process of cellulose digestion takes some time, somewhere between 9 to 12 hours. As such, cows are not slow eaters as per the usual assumption but the digestion of cellulose takes a longer period of time. The following is a basic summary of the cow digestive system:
|1 – Rumen||The largest component of the stomach. It is in this chamber where plant material is temporarily stored before returning to the mouth for chewing.|
|2 – Reticulum||The bacterial action is continued.
Finely ground plant matter is separated from course feedstuff and hard pieces of wood retained.
|3 – Omasum||Food is ground further and absorption of water occurs in this part of the stomach.|
|4 – Abomasum||This is often termed the true stomach, the enzyme action for the breakdown of protein takes place in this region. From this part of the stomach, digestion occurs similarly to monogastric beings.
What Bacteria Helps Cows Digest Cellulose?
Similar to all vertebrates, ruminants Artiodactyla are not able to directly digest cellulose due to lack of relevant enzymes. As such, cows can digest cellulose through the use of micro-organisms known as anaerobic bacteria. Note that as the name suggests, this digestive process by anaerobic bacteria does not require oxygen. These micro-organisms responsible for the digestion of cellulose are primarily found in the rumen. The ruminococcus bacteria is most important in the breakdown of plant fibre into the monosaccharide glucose which can be further digested through glycolysis. Therefore, cows can digest cellulose without necessarily encoding for the required enzyme. Other types of bacteria responsible for the digestion of plant matter include megasphaera, fibrobacter, streptococcus, escherichia, chytridiomycetes fungi as well as methanogens. There are hundreds of different kinds of bacteria found in the rumen that help to efficiently break down cellulose. It is said that cellulose digestive microbe appear as soon as 38 hours after birth. According to specialists in animal science, about 70% of the bacteria in the rumen are yet to be discovered. Nonetheless, despite the numerous amount of bacteria found in the rumen, supposedly only 0.3% are considered as cellulolytic bacteria. Another point to note is that the amount of ruminococcus bacteria found in the rumen depends on the type of feed. Livestock with dietary plans that primarily consist of plant matter develop high levels of cellulolytic bacteria and the opposite applies to those provided with a dietary plan with limited plant material.
Which Animal Digests Cellulose?
Since cows can digest cellulose, other species with a similar digestive system are also able to efficiently breakdown cellulose. Basically all ruminants have digestive systems that allow for the digestion of cellulose. This includes goats and sheep as they also have stomachs made up of four distinct compartments that each play a similar role in the digestive process. Research findings reveal that over millions of years of evolution has allowed animal species to adapt to different climates and conditions as a means to survive. As such, just as cows can digest cellulose, other animal species such as tapirs and horses have digestive systems that also contain the necessary bacteria to digest cellulose. However, the fermentation process mainly takes place in the intestine as opposed to the stomach. Resultantly, they are also able to extract nutrients from plants though not sufficient for their dietary requirements. That being said, cows can digest cellulose just as most domestic animals with dietary plans consisting of forage.