Carnivores eat the digestive system

Animals Digestive systems in animals

SEND DATEThu, January 15, 2015 | 10:00 pm | SWR television

Whether carnivores, herbivores or omnivores - nature has developed many fascinating digestive strategies in the course of evolution.

Rabbits are a good example of surprising digestive solutions. Almost everyone who has watched the cute animals for a long time will have seen it: Rabbits keep feeding their own droppings. A look inside makes it clear why:

In rabbits, some of the food initially ends up in the appendix. There microorganisms help to break down the hard-to-digest vegetable food. Then the porridge migrates as "soft excrement" through the large intestine and is excreted. These droppings are eaten again. Only now can the nutrients be absorbed in the small intestine.

The nutrients are only available during the second digestion

Gerhard Breves is professor for veterinary gastroenterology at the University of Veterinary Medicine in Hanover. Unquestionably one of the experts on digestive systems in animals. Although he has been active in this research field for over three decades, you can still feel his enthusiasm for the topic:

"The fascinating thing about gastroenterology is that we can observe very different digestive strategies that have developed in individual animal species in the course of evolution. And these differences actually exist in the interaction between the body's own and microbial digestive processes."

Cows have the same hard-to-digest plant foods as rabbits. But cows don't have to eat their dung to get valuable nutrients. Your digestive strategy is different:

Cows have four stomachs. First the grass goes into the first, largest stomach, the rumen. It has the volume of half a bathtub filling. The grass lies here for up to three days and is fermented by microorganisms. The actually indigestible cellulose is broken down by microogranisms. In principle, it is the same process that takes place in the rabbit's appendix. Then the "silage" is choked back into the mouth to ruminate. Only in the abomasum is the porridge further broken down with the body's own acids and enzymes. The actual absorption into the body, the "absorption" of the nutrients, takes place in the small intestine.

"Foreign" digestion of cellulose

With birds, the whole thing looks completely different. The main food for the pelicans in the Hanover Zoo is fish. Since they have no jaws and no teeth, they swallow the fish in one piece.

Then the fish get into the crop and are soaked. In the glandular stomach, stomach acids and enzymes are added and break down proteins and fats. The gizzard has stored stones as dentures. This is where the porridge is chewed. Again, it is the small intestine where the vast majority of the nutrients are absorbed.

And where does the bird droppings get their peculiar appearance? The mixture of dark and light faeces?

Birds have a sewer in front of the "last exit". Here the dark intestinal contents are only briefly mixed with white urine. And then eliminated. Hence the typical light-dark mixture

As a typical representative of carnivores, we visit an agame in the zoo. For the digestion of the locust, this lizard basically has the same gastrointestinal structure as all predators, explains Gerhard Breves from the University of Veterinary Medicine in Hanover:

"This means that the gastric and small intestine area in carnivores is much stronger than the large intestine. The reason for this is that the gastric and small intestine area is much more important in carnivores, whereas in herbivores, where the importance is the microbial digestive processes are greater, and the large intestine is also better developed overall. "

"The body's digestion" with acids and enzymes

For the zookeepers at the Hanover Zoo, it doesn't matter whether their animals chew with their teeth or with their stomachs. Or whether your protégés ferment the plant food in the appendix or in the rumen. One thing is very clear: in the end it comes out at the back. And the carers have to make sure that everything is clean again soon.

Frank Wittig

Status: 8/8/2014, 11:39 p.m.