Date: 3/7/08 THU
I will be focusing on non-ruminant herbivores, something that is very different from the ruminants,as discussed on the last post.
Some herbivores are non-ruminants, which include pigs, zebra, hippopotamus and rhinoceros. They each have a single stomach compartment (unlike the 4 chambered stomach of ruminants). The non-ruminants can be further subdivided into those who have similar digestive tracts to humans (i.e. the pig) or more specialized digestive tracts. I would not talk about digestive tracts that are similar to humans as we had already dicussed it on the third post. Non- ruminant that have more specialized digestive tracts (i.e. poultry, birds), have a few differences between the ones which have similar digestive tracts to humans .
The first important change is in the mouth. They have a beak but do not use teeth. They mix the food with saliva but virtually no mastication (breaking of food particles into smaller pieces) occurs in the mouth.
Secondly, they swallow their food and pass down the esophagus a short distance to a large pouch.This pouch called a crop is a kind of storage area in the bird's digestive tract. It is here that saliva begins to work at breaking down the food. The food is next moved downward to the proventiculus. It is still like the crop a portion of the esophagus, but it is also sometimes referred to as the glandular stomach. This name comes from its role in introducing hydrochloric acid and digestive enzymes to the food.
Next, the fermentation takes place further down their digestive system. The gizzard is a large sack lined with very powerful muscles,which contracts against the food and slowly with the help of some grit breaks the food in very tiny particles. These fine particles easily pass out of the gizzard into the small intestines where most of the nutrients from the feed are digested and absorbed by the bird. This means that by the time the tough walls of the plant cells are broken down, the food has already gone past the part of the gut that absorbs most nutrients.
Hence, we have covered digestive system of non-ruminant. Next post would be the characteristics all herbivores should have in order to compare more accurately. Off for more CRAZY RESEARCH...