Basic Biology of Chicken

1. BASICBIOLOGY OF CHICKEN
Department of Livestock Production Management
College of veterinary Sciences &AH
Central Agricultural University
Selesih : Aizawl : Mizoram
Dr.Lakshya J Kakati
2016-V-14(M)

2. SKELETON
 compact, light in weight , and very strong.
 only one movable vertebra along its length but
vertebrae of neck and tail are moveable.
 pneumatic bones ,that is hollow and are connected
to the respiratory system.
 Pneumatic bones_: skull , humerus , clavicle , keel ,
lumbar and sacral vertebae.
 Medullary bone fills the marrow cavity with fine
interlacing spicules of bone .
 Tibia , femur, pubic bones , sternum , ribs , ulna , toes
and scapula.

4. MUSCULAR SYSTEM
 3 principle muscle:
 Smooth muscle
 Cardiac muscle
 Skeletal muscle
Fibres are thicker
In male than female.
Dark meat : red fibres
White meat : white

6. THE SKIN
 Chickens have a relatively thin skin over most of the
body which is free of secretory gland , the only
exception is the uropygial gland or oil gland(preen
gland) found on the upper portion of tail .
 The size and colour of comb and wattles are
associated with gonad development and secretion of
the sex hormones.
 Skin color depends on combination of pigments in
upper and lower layers of skin.

7. FEATHERS

8. CIRCULATORY SYSTEM
 Chicks has a four chambered heart ,two atria and two
ventricles which allow circulation to the lung .
 Chicken blood contains from about 2.5 to 3.5 million red
blood cells per cubic mm depending on sex and age.
 Adult males contains about 500,000 more red blood cells
per cubic mm.
 Spleen : red and white cells may be formed , and which
act as reservoir of red blood cells.

10. RESPIRATORY SYSTEM
 Lungs : are rigid structures which expand and contract
during respiration.
 Air sac : 4 pairs.
 Voice
 of fowl in syrinx.
 No alveoli
 Parabronchi present

11. Air enters during inhalation through nares(heated n filtered)
trachea
bronchi( primary bronchi or
mesobronchi )
posterior sac at the
caudal end of the bird
anterior sac parabronchi
trachea back out through the
birds mouth or
nares by expiration.

12. EXCRETORY SYSTEM

13. NERVOUS SYSTEM
 The prime elements of nervous system integrates the
functions of the body.
 The nervous system is divided into two parts :
 CNS: voluntary actions of the body.
 ANS: coordination of involuntary actions of intestines ,
blood vessels and glands.
 Neo cortex or cerebral cortex : small
 Optic lobes of brain : well developed
 Hearing : well developed .
 Smell : not highly developed.

14. DIGESTIVE SYSTEM
 The chicken has simple digestive system , with few or no
microorganism living in the digestive system to help
digest . It usually take about 2.5 hrs for food to pass
through digestive tract.
 BEAK : of the bird replaces the mouth and lips.
 CROP : is a pouch formed to serve as storage area .
 PROVENTRICULUS : is the true stomach .
 Gizzard : oval organ composed of two pairs of thick red
muscles. These muscles are extremely strong and are
used to grind the food particles..

15.  PANCREAS : secrete pancreatic juice.
 LIVER : bile is produced in the liver which is necessary
for proper absorption of fat.
 SMALL INTESTINE : The digestion and absorption of
food .
 CECA : some digestion of fibre may take place in the
caeca by action of microorganism.
 RECTUM AND CLOACA : The large intestine is short
and consist of a short rectum leading to cloaca.The
cloaca is common passage for digestive, urinary and
reproductive passages which opens externally at vent.

16. THANK YOU

17. REPRODUCTIVE SYSTEM
 FEMALE
 OVARIES :A Laying hen contain 5-6 large yellow
developing egg yolks(follicles) .
 THE OVIDUCT :divided into 5 regions : Infundibulum ,
Magnum where thick albumen is secreted , Isthmus
which secretes the shell membrane , Uterus or shell
gland and , the Vagina the passage to the cloaca.
 Yolk formation : A yolk is produced by the hen ovary in a
process called ovulation. The whole ovulation takes 25
hrs.

18.  The process of egg formation strat by one yolk
getting the major amount of yolk material produced
in liver and transported to ovary.;v.j,/
 Egg white formation : Magnum secrete albumen.
Four distinct layers of albumen are the chalaziferous
layer attached to the yolk ; inner thin albumen ; thick
albumen ; and outer thin albumen .
 Shell Membrane formation : added to egg in the
isthmus . These membranes are made up of many
interlacing fibres .The membranes adhere to each
other except at large end of the egg to form air cell.
 Egg shell :Uterus shell is formed , 19-20 hrs is
required. It is made of calcium carbonate. The final
layer of shell is known as cuticle.

20. CONTD…
 MALE
 Testes : two bean shaped yellowish white bodies . Left is
usually larger than right testes.
 Testes never descend into an external scrotum.
 Ductus epidymis is also very short .
 In avian species sperms are stored mainly in the distal
part of ductus deferens .
 The accessory reproductive organs like seminal
vesicles, prostate , cowper’s gland and urethral glands
are absent in cocks.

21. CONTD…
 Each testes give rise to a relatively short epididymis , through which
the spermatozoa pass to a long coied duct , the ductus deferens. The
ductus deferens opens directly over the grove in rudimentary
copulatory organ situated in the cloaca.

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