Quiz: why does a cow have 4 stomachs

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In summary, cows heavily rely on micro-organisms for the digestion of food because they are able to digest cellulose, which is found in plant cell walls, and make it available for their metabolic needs. This is unlike "higher organisms" who do not possess the necessary enzymes to break down cellulose. Cows and other herbivores utilize a similar system, which is why they have evolved to have four stomachs to carry around large amounts of bacteria for digestion. The fermentation products produced by the bacteria are the main source of energy and nutrients for the cow. The lack of cellulase enzymes in animals is seen in all related animals, such as ruminants. It is likely that the cow evolved with
  • #1
Monique
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  • #2
Each section have different function. Cow relie heavily on microorganism for the digestion of food. A normal stomach does not have an appropriate environment for bacteria.

Here some info the stomach.

http://edis.ifas.ufl.edu/BODY_DS061 [Broken]
http://arbl.cvmbs.colostate.edu/hbooks/pathphys/digestion/herbivores/rumen_anat.html [Broken]
 
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  • #3
So why does the cow heavily rely on micro-organisms for its digestion? (it is an interesting issue)
 
  • #4
Cows rely on micro-organisms because, unlike "higher organisms", they can digest cellulose (~plant cell walls) and make it available for the cow's metabolic needs. Other herbivores utilize similar systems. I read that cows, like elephants, etc. are large partly because they need to carry around this large vat of digesting bacteria to process large amounts of relatively nutrient-poor grass.
 
  • #5
Don't you think that is strange? Cows don't have the enzyme to digest cellulose! The only thing they eat all day is nutrients with a very thick layer of cellulose around it!

Didn't evolution do its work?

Apparently it is much easier to change the body plan of an animal, by making four stomachs out of one, than it is to generate a novel enzyme :)

I still find it strange though that the enzyme is missing, did we loose it in evolution or did it never exist in eukaryotes? And if it never existed, what did the ancestor live on?

There is the same issue in humans, we also depend on the enzymes of micro-organisms for the digestion of our food.
 
  • #6
That is a easy one. Cow cannot break down cellulose because it does not possesses cellulase. Cellulase is produce by microorganism. Therefore, bacteria breaks down the cellulose and use it for fermentation. Fermentation produce nutrient for the cow. The cow absorb the fermentation produce and the digeste the dead micro-organism.
 
  • #7
The cow uses the fermentation product? I thought they actually break open a number of the bacteria after which the enzyme leaks into the environment and becomes available for the cow?

and see my previous post for the other questions
 
  • #8
Originally posted by Monique
I still find it strange though that the enzyme is missing, did we loose it in evolution or did it never exist in eukaryotes?

Protozoan have the cellulase. There are the major cellulose digester in the cow. It appears that no animal have cellulase but I know there some studies done on grasing insect. There are trying to find if cellulose can be broke down without the micro-organism.


Originally posted by Monique
And if it never existed, what did the ancestor live on?

Probably on the same thing. We eat salad but we don't get much out of it. Horse and rabbit have the fermentative pouch at the end of the G.I. track. They eat the feces to recylce the lost nutrients.

Originally posted by Monique
There is the same issue in humans, we also depend on the enzymes of micro-organisms for the digestion of our food.

We do not rely on bacteria and other micro-organism for the digestion of our food. Very few micro-organism in the human digestive track give something back and it is mostly vitamines.
 
  • #9
Originally posted by The Opiner
Cows rely on micro-organisms because, unlike "higher organisms", they can digest cellulose (~plant cell walls) and make it available for the cow's metabolic needs.

What do you mean unlike higher organism? Only lower organism can break down cellulose.


Originally posted by Monique
I thought they actually break open a number of the bacteria after which the enzyme leaks into the environment and becomes available for the cow?

The cow also digest the dead mirco-organism but the fermentation product appears to be the major source of energy and nutrients.
 
  • #10
How many genes does the cow have? Is it still not strange it can't efficiently break down cellulose?

It has to depend on lots of chewing, regurgitations, 4 stomachs with bacteria. How is the efficiency of absorbing nutrients with this system? I mean a percentage?
 
  • #11
Originally posted by Monique
How many genes does the cow have? Is it still not strange it can't efficiently break down cellulose?

It has to depend on lots of chewing, regurgitations, 4 stomachs with bacteria. How is the efficiency of absorbing nutrients with this system? I mean a percentage?

I don't know the efficiency of the process but how efficiently could a cow use the break-down cellulose? Also, how would the cow acqire the cellulase enzymes. The strategy employ by the cow is seen in all related animals, the ruminants. It has not been found in any animals so far.
 
  • #12
Originally posted by iansmith
Also, how would the cow acqire the cellulase enzymes.
Euhh... how does an organism become an organism with a metabolism? By somehow modifying genes so to make the correct enzyme.

So you really are not surprised that animals don't have a cellulase enzyme?

When do you think that humans started eating meat? Evolutionarily very recent at the time that the Cro-Magnon appeared, some 50-35 ky ago. Only 3000 yrs ago (160 generations) did we start farming animals, we depended largely on plant material, how did we digest it without the help of bacteria?

Why do we carry more bacteria with us than cells in our body? You are really saying they don't help in breaking down food for us?
 
  • #13
Perhaps this is an example of co-evolution at work - the cow could have developed with these bacteria in its gut, and thus had little or no selective pressure to adapt its own system. Some other animals "farm" fungi, using them to help digest tough vegetation.

Only 3000 yrs ago (160 generations) did we start farming animals, we depended largely on plant material, how did we digest it without the help of bacteria?
I am not certain, but I think the appendix had something to do with it.
 
  • #14
Originally posted by FZ+
Perhaps this is an example of co-evolution at work - the cow could have developed with these bacteria in its gut, and thus had little or no selective pressure to adapt its own system. Some other animals "farm" fungi, using them to help digest tough vegetation.
Where did the cow come from then? Since none (I assume) of the (higher) eukaryotes have cellulase, we would have had to live in symbiosis with bacteria a very very long time. Then why is it that only the cow (and other remants? (deer, antelopes, cattle, sheep, and goats)) have multiple stomachs?

Remember, I am also trying to think way back along the evolutionary line, since plants are the primary source of nutrition a eukaryotic cell would have been required to be able to digest it right?

Ah, wait. I just thought of something: very young leaves contain very little cellulose, maybe way back there was an abundance of these young leaves and thus an enzyme would not be required. Then later on, the young leaves became more scarce and all of a sudden the need was there to digest the tougher older leaves. Since there wasn't enough time to evolve a new enzyme, another faster path was chosen, and that was the symbiosis with bacteria and adaption of the body plan to house these bacteria more efficiently.
 
  • #15
Good hypothesis?
 
  • #16
You mean a gradual change from browsers to grazers?

Sounds good to me, though my opinion means little...
 
  • #17
Gradual, but fast enought that it didn't allow for an enzyme to emerge from the chemistry of life. Emergency measures had to be taken, which was symbiosis followed by anatomical changes.

I then wonder why deer, antelopes, cattle, sheep, and goats? Grass might be the clue.. when did grass start taking over the earth?
 
  • #18
Originally posted by Monique
So you really are not surprised that animals don't have a cellulase enzyme?

I am not suprised but if it is not present in any animals than is was probably not required.

Originally posted by Monique
When do you think that humans started eating meat? Evolutionarily very recent at the time that the Cro-Magnon appeared, some 50-35 ky ago. Only 3000 yrs ago (160 generations) did we start farming animals, we depended largely on plant material, how did we digest it without the help of bacteria?

Chimp eat meat. So our ancestor must of eaten meat when they stated to arise. Also, inuit depends on meat only for their survival. Also the plant material that we utilize contain a higher concentration of other sugar than leaf materials. We eat the fruit, the grain and the roots. How much cellulose is present in those parts and what is the ratio digestible sugar to cellulose in those parts? We did not need the enzyme.

Originally posted by Monique
Why do we carry more bacteria with us than cells in our body? You are really saying they don't help in breaking down food for us?

Bacteria are only present in your large intestine. Your food is mostly digested at this point. Technically speaking, the rumen of the cow is a modified oesophagus. Birds also have this kind of pouch. It call the crop but it has another function. Most bacteria that we carry do not help at all. You got some on your skin, respiratory track (some people carry so nasty pathogens)and women have then in their reproductive track. It is theorize that in the intestine most bacteria are blocking the binding site for potential pathogens.

Originally posted by Monique
Then why is it that only the cow (and other remants? (deer, antelopes, cattle, sheep, and goats)) have multiple stomachs?

Ruminants (cattles, sheep and goats) all have multiple stomach. The horse and rabbits have a modifed large intestine which serve the same function but absorbtion of nutrient is not as efficient as in the rumeninants.
 
  • #19
Originally posted by iansmith
I am not suprised but if it is not present in any animals than is was probably not required.
You should be surprised, since that will lead you to form hypotheses on why thing are the way they are.

Chimp eat meat. So our ancestor must of eaten meat when they stated to arise.
Wheeew! That is scientific thinking? First of all, since when are chimps carnivorous? Second: they could have started eating meat occasionally independently from the human line.

Also, inuit depends on meat only for their survival.
Mostly on fats. This is not a good example of where evolution started with the development of an organism that required to get nutrition from another place than the sun.

Also the plant material that we utilize contain a higher concentration of other sugar than leaf materials. We eat the fruit, the grain and the roots. How much cellulose is present in those parts and what is the ratio digestible sugar to cellulose in those parts? We did not need the enzyme.
Well, maybe, it is hard to say whether the cave people were eating the leaves or not.

Bacteria are only present in your large intestine. Your food is mostly digested at this point.
I don't believe that, humans carry more bacteria in their mouth than a dog does.

You got some on your skin, respiratory track (some people carry so nasty pathogens)and women have then in their reproductive track. It is theorize that in the intestine most bacteria are blocking the binding site for potential pathogens.
That is a valid argument, but we could just kill all the bacteria right? For some reason we kept them. How come only the good bacteria live inside of you?
 
  • #20
Originally posted by Monique
Wheeew! That is scientific thinking? First of all, since when are chimps carnivorous? Second: they could have started eating meat occasionally independently from the human line.

Chimp eat small monkeys and they are good at it. It is not a major source of energy but they do it.
http://www.sciam.com/article.cfm?articleID=00060CFC-D2D9-1C6F-84A9809EC588EF21
We share a common ancestor and they could of had similar eating habits of the chimp. Also meat eating could of independently arise in human and chimp.

Originally posted by Monique
Mostly on fats. This is not a good example of where evolution started with the development of an organism that required to get nutrition from another place than the sun.

Could a vegeterian adapted human survive so well in this enviroment. It does tell us how the organism started but it give some clues.

Originally posted by Monique
Well, maybe, it is hard to say whether the cave people were eating the leaves or not.

If our ancestor were eating signifcantly large quantity of leaves would we keep the habit. What is the diet of "primitve" tribes? How much leaf component are they eating in their diet. I can give us significant inside to some of the eating habits of our ancestor. Chimp do have 20% of their diet compose of leaf.

Originally posted by Monique
I don't believe that, humans carry more bacteria in their mouth than a dog does.

I long does our food stay in our mouth. It is not signficantfor bacteria to digest the food. Any way they will probably die in your stomach and what is left will not have a major impact on the digestion of the food.


Originally posted by Monique
That is a valid argument, but we could just kill all the bacteria right? For some reason we kept them. How come only the good bacteria live inside of you?

We do not only have good bacteria in inside us. Some peope carry virulent strain of Neisseria meningitis and Staphylococcus aureus in the nasal cavity, some carry Salmonella. Most species of bacteria inside will not harm us or will not be beneficial. We do not kill the bacteria inhabiting us because they adapted to us. Our insides is an excellent environment for them.
 
  • #21
Originally posted by Monique
Where did the cow come from then? Since none (I assume) of the (higher) eukaryotes have cellulase, we would have had to live in symbiosis with bacteria a very very long time. Then why is it that only the cow (and other remants? (deer, antelopes, cattle, sheep, and goats)) have multiple stomachs?
It is not strange that organisms should live in Symbiosis for a long time. Eukaryotes are only a collection of symbiotic/Mutualistic prokaryotes afterall.

Also, remember that there is an Arms race between plants and animals. Plants generally don't want their leaves eaten, animals want to eat them. Plants defend by making the leaves harder to eat, animal react by forming tougher teeth, a gizzard, or a way of breaking down cellulose etc... things change on both sides.
 
  • #22
Originally posted by iansmith
Chimp eat small monkeys and they are good at it. It is not a major source of energy but they do it.
We share a common ancestor and they could of had similar eating habits of the chimp. Also meat eating could of independently arise in human and chimp.
I am aware chimps eat their young, but do we do that too? No, so it is unlikely that chimps and humans eat meat for the reason and thus that it was because of an ancestor.

Could a vegeterian adapted human survive so well in this enviroment. It does tell us how the organism started but it give some clues.
What leads you to believe that Inuits are healthy and had no problems in surviving? What happened in the times of the west-Indies companies sailing the seas, they got all kinds of diseases due to lacking vitamins etc because they didn't have fresh fruit and vegetables. Again, these examples of Inuits and chimps are evolutionary too recent!

If our ancestor were eating signifcantly large quantity of leaves would we keep the habit. What is the diet of "primitve" tribes? How much leaf component are they eating in their diet. I can give us significant inside to some of the eating habits of our ancestor. Chimp do have 20% of their diet compose of leaf.
Ok, fine. So let's forget about our branch. Let's think about the other branch that developed into animals: the first heterotroph.

I long does our food stay in our mouth. It is not signficantfor bacteria to digest the food. Any way they will probably die in your stomach and what is left will not have a major impact on the digestion of the food.
Yes, they die in the stomach and what happens to the enzymes that get released? They are released to the environment and thus enrich our enzymatic capacity (if the enzyme still has activity at low pH).

We do not only have good bacteria in inside us. Some peope carry virulent strain of Neisseria meningitis and Staphylococcus aureus in the nasal cavity, some carry Salmonella. Most species of bacteria inside will not harm us or will not be beneficial. We do not kill the bacteria inhabiting us because they adapted to us. Our insides is an excellent environment for them.
What happens to a baby when it first starts taking food? It can't digest it. Why? Untill after a while the bowel get populated with bacteria and things stabilize. Bacteria in our bowel are attacked by enzymes too and brake open and release their cytoplasms, it is very easy to state that this doesn't help us. Do you have a publication to back yourself up?
 
  • #23
Originally posted by Monique
I am aware chimps eat their young, but do we do that too? No, so it is unlikely that chimps and humans eat meat for the reason and thus that it was because of an ancestor.

I am not taking about eating their young, Chimp actually hunt. The reason that we eat meat migth not be the same as chimps but it could of started for the same reason.

Originally posted by Monique
What leads you to believe that Inuits are healthy and had no problems in surviving? What happened in the times of the west-Indies companies sailing the seas, they got all kinds of diseases due to lacking vitamins etc because they didn't have fresh fruit and vegetables. Again, these examples of Inuits and chimps are evolutionary too recent!

Your example is bad. Inuit were healthy. They are very well adapted to their enviroment. They did suffer from the same disease as the European that travel to the north.
At the present time inuits are suffering from health problem due to a shift to a North-American/European life style.

Originally posted by Monique
Ok, fine. So let's forget about our branch. Let's think about the other branch that developed into animals: the first heterotroph.

Some heterotroph do possesses cellulase but it migth not be related to animals.

Originally posted by Monique
Yes, they die in the stomach and what happens to the enzymes that get released? They are released to the environment and thus enrich our enzymatic capacity (if the enzyme still has activity at low pH).

The enzyme is probably not active at pH 2.0 and it probably get degraded in the stomach.

Originally posted by Monique
What happens to a baby when it first starts taking food? It can't digest it. Why? Untill after a while the bowel get populated with bacteria and things stabilize.

The version I heard is that the stomach and most of G.I. track is not fully functionnal yet. How long does the lack of digestion persit? The microflora is quite rich 48 hour after birth. Babies get into contact with bacteria during their birth. Vaginal bacteria can enter the G-I track. Within hours the baby get kisses and is feed by his mother.

Originally posted by Monique
Bacteria in our bowel are attacked by enzymes too and brake open and release their cytoplasms, it is very easy to state that this doesn't help us. Do you have a publication to back yourself up?

The significant of digestion by bacteria is very minimal. Bacteria do give us vitamines and organic acid but those are byproduct of their metabolism. If bacteria had a significant digestive power ther would be not lactose or any sugar intolerance. Bacteria feed on these sugar for them self not for our benefit.

The only references I have are my notes from my microbiology class. Do you have any reference to back your self up.
 
  • #24
Originally posted by iansmith
Your example is bad. Inuit were healthy. They are very well adapted to their enviroment. They did suffer from the same disease as the European that travel to the north.
You are saying they were healthy and at the same time they suffered from disease? The only reason Inuits were able to survive was that their diet consisted of fats from the seals, which contained necessary nutrients.

The enzyme is probably not active at pH 2.0 and it probably get degraded in the stomach.
I am thinking about a whole range of enzymes in this case which might be usefull for us.

Within hours the baby get kisses and is feed by his mother.
Ok, just understand that there are no bacteria in breast milk right?

If bacteria had a significant digestive power ther would be not lactose or any sugar intolerance. Bacteria feed on these sugar for them self not for our benefit.
Good argument.

The only references I have are my notes from my microbiology class. Do you have any reference to back your self up.
I don't, I look at the situation and postulate an hypothesis that an interaction is taking place, while you argued that nothing is going on which contradicts the observation. Btw, I have the example of the cow backing me up that bacteria are important in digestion.
 
  • #25
Originally posted by Monique
You are saying they were healthy and at the same time they suffered from disease?

I made a mistake it should read "They did not suffer from the same disease"

I am thinking about a whole range of enzymes in this case which might be usefull for us.

Do you have any example? Any possible theory?

Ok, just understand that there are no bacteria in breast milk right?

There is bacteria in the breast milk. Some come from the skin and other get into the mammary channels.

Btw, I have the example of the cow backing me up that bacteria are important in digestion.

There a major difference between human and cow. The microflora that are important for the cow are before its stomach whereas in human the microflora it also at the exit point.
 
  • #26
Ok, so you are saying that all these health-drinks and yoghurts with added bacteria to enrich the micro-flora of the bowel are all based on air and are not backed up by any scientific data?

Just curious, I don't know.
 
  • #27
The probiotic component of food is use to promote a good microflora because there some bacteria that can establish themself and cause harm to the host such as clostridium. The probiotic ensure that benefial bacteria are maintain. The probiotic could reduce gaz production, have more beneficial secondary metabolites but it will not have an effect on the digestion of the food.

I have not seen any scientific data that prove that digestion is improve significantly.
 
  • #28
It migth be off-topic but micro-flora of mammals may have another function, desentizing the immune system. Researcher have observed that baby grown on a farm are less likely to develop auto-immune diseae such as allergies. They also tested this on various animal models and had similar observation.
 
  • #29
But does that have to do with the microflora? How does a baby know which of the microflora is good and which is bad? I wouldn't want to desensitize against bad ones..

I have heard of the research you are talking about, I am not sure what the mode of entry of the allergen is, inhalation perhaps? Desensitation still works in adults too, btw, that is how people with peanut allergies are now treated: very low doses of peanut epitope are given over a few weeks and these people's immune system learn it is not harmfull and loose their allergy. Pretty smart person who thought of that :)
 
  • #30
Originally posted by Monique
But does that have to do with the microflora?

Researcher took mice that were suspetible to diabetes. One group was raise in a sterile environment so mice would not have a micro-flora. The other group was raised normally. The normal did not develop diabetes whereas in the sterile group 2 mice out 3 develop diabetes.

They also did an experiment on human baby. Babies suceptible to asthma were inoculated with probiotics, other suceptible babies were not. Probiotics had a decrease in the symptomes compare to the control group.

Originally posted by Monique
How does a baby know which of the microflora is good and which is bad? I wouldn't want to desensitize against bad ones..

I don't think the baby can differentiate between good and bad but the desentization is not against bacteria but against normal enviromental compound that could be allergens.

Originally posted by Monique
I am not sure what the mode of entry of the allergen is, inhalation perhaps?

Ingestion too. The researchers proposed that dentric cells are responsible to id good or bad antigens. So any antigens must either touch the mucous membrane or get inside scar tissues.
 

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