THE DIGESTIVE SYSTEM

Basically, there are two types of digestive system in farm animal they are:

1.   Digestive System In Ruminant: The main characteristics of this group is the possession of complicated stomach which is divided into four units i.e. Rumen, Reticulum, Omasum and Abomasum which is the true stomach. Examples of animals in this category are goat, sheep and cattle which are otherwise called animals that chew cud.

2.   Digestive System Non-ruminant: Animals that are in this group include birds. They have simple or single stomach which explains why they feed on low fibre feeds.

THE DIGESTIVE SYSTEM OF A RUMINANT ANIMAL

The physiology of digestion in ruminant animal is directed into four parts i.e.

1.   Rumen

2.   Reticulum

3.   Omasum

4.   Abomasums

The rumen and reticulum contain several bacteria and other micro organisms i.e. (yeast and protozoan) which are capable of digesting cellulose and fibrous feed such as grasses, paper and cotton by the process of fermentation giving sugar and fatty acid as their bye products.

          The grasses are taking in through the mouth and passes through the oesophagus to enter into the first stomach, rumen where digestion of cellulose takes place, the animal also store a lot of undigested grass in this compartment. Consequently the animal lays down and by anti-peristaltic movement of the stomach the undigested grasses or cud passes from the rumen to the reticulum from where it re-enters the oestophagus and finally gets back to the mouth for re-mastication.

This time the semi-liquid goes into the third chamber (omasum) and then to the last chamber (Abomasum) where gastric juice is secreted into the semi-digested food or feed called chime. The chime then passes through the duodenum and it passes into the intestine where complete digestion and absorption takes place. The undigested material passes through the anus as dung.

THE DIGESTIVE SYSTEM OF A NON-RUMINANT ANIMAL (FOR BIRDS)

          Birds are generally referred to as monogastric animal because they have single or simple, stomach. The food is taken in by toothless beak and passes through the aesophagus and lowered into a sackline material that is called the crop which serves as a temporary storage organ and it enables the animal to feed for a longer period. The digestive system in birds is characterized by two chambers namely proventiculus which secrets the gastric juice for adequate moistening of the feed before it is passed into the second chamber called the Gizzard. The gizzard is heavily rigged with high muscular feature that enhances a mechanical grinding or turning of the food or feed consequently the grinded feed is passed into the duodenum and small intestine where further digestion and absorption of food takes place. This is later passed into the rectum or large intestine for an onward transmission or passage to the caecum where absorption of moisture takes place. The undigested food or feed are removed from the tract as faeces through the cloaca.  

THE STOMACH

The stomach of the bird consist of two parts, the first part is the proventiculus or glandular stomach which is thin walled. It secrets gastric juice to moisten the food or feed and pass it on to the second chamber known as the gizzard.

THE GIZZARD

          The gizzard is thin walled and heavily rigged. Inside the gizzard the food undergoes a lot of muscular contraction and relaxation before it is grinded into a fine pasty mass. This process is aided by pebbles and stones which are contained in the gizzard.

THE SMALL INTESTINE   

The first of this is the duodenum which receives the bye-salt produced by the liver, the pancreatic juice produced by the pancreas.

THE LARGE INTESTINE

In the large intestine, watery re-absorption continues

CAECUM

This is between large intestine and small intestine and they are concerned with the digestion of fibrous feed or material i.e. cellulose and they are also responsible for absorption of water.

VENT/CLOACA

This is responsible for the expulsion of faces material or the waste material

DIFFERENCES BETWEEN DIGESTIVE SYSTEM OF RUMINANT AND NON-RUMINANT

	Ruminant	Non-ruminant
1	Possession of complex stomach	Possession of simple stomach
2	Ability to digest fibrous feed material	Inability to digest fibrous feed material except simple sugar such as grains, tuber
3	Ability to synthesize protein required by the body	They are usually supplied by feed containing protein at required quantity
4	Digestion is added by bacteria	Digestion is not added by bacteria