the digestive system of farm animals

The digestive system of farm animals is a complex and important system that helps them to break down food into essential nutrients and energy that their bodies need to grow and function properly. In this blog post, we will delve into the types of digestive systems found in farm animals, common diseases of the digestive system, and how the digestive system works.

Types of digestive systems in farm animals

The digestive system of farm animals can be divided into four main types: monogastric, ruminant, pseudo ruminant, and hindgut fermenter.

  1. Monogastric digestive system: This type of digestive system is found in animals such as pigs, horses, and dogs. They have a simple stomach with one chamber that produces digestive enzymes and acids to break down food.
  2. Ruminant digestive system: This type of digestive system is found in animals such as cattle, sheep, and goats. They have a four-chambered stomach that includes the rumen, reticulum, omasum, and abomasum. The rumen and reticulum store partially digested food, allowing the animal to regurgitate and re-chew the food (chewing the cud) to further break it down.
  3. Pseudoruminant digestive system: This type of digestive system is found in animals such as deer and llamas. They have a three-chambered stomach that includes the rumen, reticulum, and omasum, but they do not have the abomasum, which is the true stomach of ruminants.
  4. Hindgut fermenter digestive system: This type of digestive system is found in animals such as horses and rabbits. They have simple stomachs like monogastric animals, but their large intestines contain microbes that ferment the food, breaking it down further to extract additional nutrients.

Diseases of the digestive system in farm animals

Just like in humans, the digestive system of farm animals can be prone to certain diseases and disorders. Some of the most common diseases include:

  1. Colic: This is a painful condition that can affect the digestive tract of horses, causing abdominal pain and discomfort.
  2. Bloat: This condition occurs when the rumen of ruminants becomes filled with gas, causing the animal to become bloated and uncomfortable.
  3. Ulcers: This condition can occur in both ruminants and monogastric animals, causing sores to develop in the stomach lining.
  4. Diarrhoea: This condition can be caused by a variety of factors, including bacteria, viruses, parasites, or stress.

How does the digestive system work in farm animals?

The digestive system of farm animals works by breaking down food into smaller particles, extracting the essential nutrients, and eliminating waste products. The process begins in the mouth, where the animal chews its food, grinding it into smaller pieces and mixing it with saliva.

The food then travels down the oesophagus and into the stomach, where digestive enzymes and acids help to break down the food into smaller particles. In ruminants, the partially digested food is stored in the rumen and reticulum, allowing the animal to regurgitate and re-chew the food (chewing the cud) to further break it down.

From the stomach, the food moves into the small intestine, where most of the nutrients are absorbed into the bloodstream. Any remaining waste products are then passed into the large intestine, where the microbes in hindgut fermenters help to break down the food further, extracting additional nutrients. The waste products are then eliminated through the rectum and anus.

The digestive system of a farm animal includes all the organs and tissues associated with the breaking down or digestion of food in the body.

parts of a cow
labelled parts of a cattle

It includes the teeth or beak, tongue, the alimentary canal or digestive tract and all the associated gland, secretory enzymes and other body fluids.
Farm animals are grouped into two main classes based on the nature of their alimentary canal or digestive tract. These are:

Mono gastric or Non-ruminant Animals:

These are animals which possess only one stomach and they do not ruminate (i.e. they do not chew the cud). In other words, these animals have a simple stomach and cannot digest cellulose and fibres properly. Examples are the pig, rabbit and poultry birds like the domestic fowl.

Polygastric or Ruminant Animals

: These are farm animals which possess four stomach compartments (complex stomach) and hence, they can ruminate or chew the cud. The four stomach compartments are rumen (the largest). Reticulum, omasun and abomasun (true stomach).

The rumen (pouch): It has several tongue-like protections called papillae. It also has a soft towel-like appearance. It is the largest and the first compartment of the stomach.
Reticulum (hone comb): This is lined with a mucosal layer which is formed into a hexagonal chamber that looks like a honeycomb. It is the second compartment.

Omasun (many piles) The omasum is the third and smallest compartment. It has several “leaves” or laminae/layers.
Abomasun: This is the only glandular stomach. It is synonymous with the simple stomach of monogastric animals. The abomasum is the fourth and last compartment of the stomach.


(i) Fermentation brought about by micro-organisms takes place in the rumen
(ii) It is used for the temporary storage of feed before regurgitation for proper re-chewing
(iii) Volatile fatty acids and other gases are produced in the rumen as a result of fermentation
(iv) Absorption of volatile fatty acids takes place through the walls of the rumen

(v) Some vitamins, e.g vitamin B, are produced in the rumen
(vi) Breakdown of cellulose takes place in the rumen
(vii) Examples are cattle, sheep and goats. They are all herbivores.


Ruminant animals like cattle, sheep and goats feed mainly on grasses and they can ruminate or chew the cud because of the complex nature of their stomach.

When a ruminant animal like a cow wants to feed, it cuts the grass and swallows it with minimal chewing. The grass passes from the mouth through the oesophagus to the rumen where the grass it stored. In the rumen, the grass is acted upon by micro-organisms like bacteria and protozoa which digest the cellulose and synthesize some amino acids needed by the animal from non-protein nitrogenous substances.

When the cow has finished filling the rumen, it finds a cool place and lies down quietly. By anti-peristaltic movement of the stomach, the undigested grass passes from the rumen to the reticulum from where it re-enters the oesophagus (regurgitate) back to the mouth. The food is now chewed properly by using the molar and premolar teeth (chewing the cud) into a semi-liquid cud which is re-swallowed. This liquid cud now moves into the omasum from where it passes to the abomasum (the true stomach). The whole process is called rumination.

In the abomasum, enzymes are secreted which act on the food. Further digestion and absorption of the food take place progressively along the digestive tract. The digested food is then absorbed into the blood through the villi in the small intestine while the undigested food passes to the large intestine where they are removed through the anus as dung or faeces.


Pig has only one stomach. It does not chew the cud nor does it utilize roughages properly. The digestion in pig can be understood properly.
The pig feeds mainly on basal feeds like maize, cassava and other mashed food. Digestion of food takes place in four areas of the tract:
(i) Mouth: In the mouth, the food is chewed and mixed with saliva which contains an enzyme called ptyalin. The ptyalin converts starch to maltose. The food is now swallowed and moves by the peristaltic movement to the stomach.

(ii) Stomach: In the stomach, two enzymes, renin and pepsin, are present. Rennin acts on milk or it helps to curdle milk while pepsin converts proteins to peptones under the influence of an acid medium. The thick liquid called chime now passes to the duodenum.
(iii) Duodenum: Digestion also takes place here. Three enzymes are present and they act on different foodstuffs

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(a) Amylase: this enzyme converts starch to maltose
(b) Lipase: converts fats and oil to fatty acids and glycerol
(c) Trypsinogen: converts protein and peptones to polypeptides. These enzymes are secreted by the pancreas. The digestion of fats and oil is aided by bile which is secreted by the liver and stored in the gall bladder. The bile helps in the emulsification of fats. At the end of the digestion in the duodenum, the food (now in liquid form) called chyle passes to the ileum or small intestine.

(iv) Small intestine: The wall of the small intestine secretes many enzymes which complete the process of digestion.
The enzymes are:
(a) Lipase: which converts fats and oil to fatty acids and glycerol
(b) Erepsin converts polypeptides to amino acids
(c) Maltose converts sucrose to glucose.
(d) Sucrose converts sucrose to glucose and fructose
(e) Lactose converts to glucose and galactose.
The end product in the digestion includes the conversion of:
(i) Protein to amino
(ii) Starch to glucose
(iii) Fats and oil in amino acids

These end products (amino acids, glucose and fatty acid and glycerol) are absorbed in the small intestine by a structure called the villi. The undigested food materials are passed to the large intestine from where they are ejected through the anus as faeces or dung.
The digestion of food in rabbits (a non-ruminant) is just like the pig except that rabbits can feed properly on grasses which are digested in the large caecum which contains micro-organisms like bacteria and protozoa.


The domestic fowl is a monogastric animal and has a simple stomach. Digestion in fowl can be explained properly.
The fowl has no teeth but the food is picked up by the beak. This food then passes on to the crop through the oesophagus. This food is stored temporarily in the crop where it is moistened and fermented by some bacteria. The food now passes on to the proventriculus where digestive enzymes are secreted on the food.
The proventriculus is often regarded as the glandular stomach because it secretes digestive enzymes on the food like pepsin and amylase.
From the proventriculus, the food moves to the gizzard where grinding takes place. With the aid of small stones or grits, the food is ground by the gizzard. From the gizzard, the food now moves to the duodenum and small intestine where further digestion and absorption take place while the undigested food materials are removed from the tract as faeces.


(i) It aids the ingestion of feed
(ii) It promotes the digestion of feed
(iii) It ensures the absorption of digested feed
(iv) It helps in the ejection of undigested feed
(v) It aids the secretion of productive hormones and digestive enzymes