Anatomy refers to the form and structure of the body while physiology refers to the functions of the forms and parts of the body. It is very important for the farmer to understand the anatomy and physiology of farm animals because it will enable him to know more about the nutrition, reproduction and management of his animals.

The body of farm animals are divided into four major groups. These are: (i) Head (ii) Thoracic cavity (iii) Abdominal cavity (iv) The limbs

(i) Head: The head is the upper part of the body. The major organs found in the head region include the brain, eyes, ears, tongue and nose.

(ii) Thoracic Cavity: The thoracic cavity refers to the chest region of the body. The major organs in the thoracic cavity include heart, lungs and treachea.

Abdominal Cavity: The abdominal cavity refers to the stomach region of the body. The major organs in the abdominal cavity include liver, uterus, stomach, oviduct or fallopian tube, kidney, ovary, spleen, intestine, gall bladder and pancreas.

(iv) Limbs: The limbs include the forelimbs (hands) and hindlimbs (legs). They are used by farm animals for walking.

Some of the systems which maintain the body are: (i) digestive system (ii) circulatory system (iii) respiratory system (iv) nervous system (v) reproductive system (vi) Skeletal system (vii) Excretory system etc.


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. It includes the teeth or beak, tongue, the alimentary canals or digestive tracts and all the associated glands, secretory enzymes and other body fluids.

Farm animals are grouped into two main classes based on the nature of their alimentary canal or digestive tracts. These are:

(1) Monogastric 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 simple stomach and cannot digest cellulose and fibres properly. Examples are the pigs, rabbits and poultry birds like the domestic fowls.

(2) 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, omasum and abomasum (true stomach).

(a) The rumen (pounch): It has several tongue-like projections called papillae. It also has a soft towel-like appearance. It is the largest and the first compartment of the stomach.

(b) Reticulum (honeycomb): This is lined with a mucosal layer which is formed into hexagonal chamber that looks like honeycomb. It is the second compartment.

(c) Omasum (many piles): The omasum is the third and smallest compartment. It has several “leaves” or laminae/layers.

(d) Abomasum: 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.

Functions of the first compartment (the rumen) of the stomach of a ruminant are:

(i) Fermentation brought about by micro-organisms takes place in the rumen.

(ii) It is used for temporary storage of feed before regurgitation for proper rechewing.

(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.

Examples are the cattle, sheep and goats. They are all herbivores.

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