Chapter 1 Avian Anatomy, Physiology and Managment

 

 

                          

Some knowledge of normal structure of the poultry is essential to appreciate the changes resulted from diseases, but extensive study of the subject is impossible in a course like this. The purpose of this chapter is to give a concise presentation of the facts about the structure of the fowl as related to normal functioning, which will perhaps be sufficient for persons to deal with poultry diseases.

 Information concerning avian anatomy, physiology and management are primarily on poultry species unless otherwise stated.

1.1 Classification of the Domestic Fowl according to .Linnaeus, 1785, binomial nomenclature system: Gallus domesticus (bankiva ).

Phylum . . . . . . . . . . . . . . . Chordata

Subphylum. . . . . . . . . . . . . Vertebrata

Class . . . . . . . . . . . . . . . . . Aves

Order . . . . . . . . . . . . . . . . . Gallinae

Family . . . . . . . . . . . . . . . . Phasianidae

Genus . . . . . . . . . . . . . . . . . Gallus

Species . . . . . . . . . . . . . . . Domesticus

 

1.2 Species and Breeds of Birds

1.2.1 The breeds of chickens

• 1. Nearly 200 varieties of chickens in America.
• 2. Only two varieties are of commercial importance, the White Leghorn and White Plymouth Rock.
• 3. Increased emphasis on performance. "Purity" of breeds are no longer important. Cross breeding to improve meat and poult egg production,
• 4. Light breeds usually for egg production. (White Leghorn). Heavy breeds for meat production. The common male line is cornish. The common female line is White Plymouth Rock.
• 5. Major poultry breeding firms usually produce one or several male only or female only foundation lines. To name a few: Arbor Acres, Shaver, Cobb, Kimber, H & N, Dekalb and Hubbare. Commercial broiler firms will purchase male and female lines from separate breeding firms, the mating of A line and B line will produce the broiler strain of birds a certain company needs. 

1.2.2 Species of Caged Birds

Within the class Aves there are 27 orders and approximately 8,600 species. 

Most of the common cage birds come from 3 orders: the Psittaciformes; the passeriformes; and 2-3 species from the Piciformes.

1.2.2.1 PSITTACINES

1.2.2.1.1 Parakeet (Melopsittacus spp)

Only one, the budgerigar (M. undulatus), is kept as a pet, it is also the most popular caged bird. Originally imported from Australia.

Slender, long-tailed bird, approx. 71/2 inches long with unique barred marking and black-ladder stripes on the head and back. Life span: 15-20 years.

Male and female birds look alike except for the cere, the male cere is blue and the female cere is pink or brown. Also, the feet of the male is bluish-gray while the feet of the female is pink-hued. Many learn to talk. 

1.2.2.1.2 Parrot (Amazona spp. and Psittacis spp.)

The Parrot is a large bird, about 15 inches long, its color is usually a shade of green with some yellow on its head. The short tail is black, green, and red, there is some blue color in the wings, and the face is fully feathered. Life span: 30-50 years. The Amazon is originated in the tropical forests of Central South America. The male and female look exactly alike and difference can be determined only by surgery.

The African Gray, the only important African parrot. Size: 14-15 inches, short tail, round head. Its tail is a solid red color while the body and head are bluish gray. The bill is black.

1.2.2.1.3 Macaw (Ara spp.)

The Macaw is the largest members of the parrot family; of which there are 30 species an& subspecies. The handsome long-tailed birds are very colorful. The birds learn to talk with ease, and can also be taught to do tricks and acrobatics. The Macaw measures 3 feet in length and is originated in tropical rain forests from Brazil to Mexico.

Macaws thrive on affection and company. In the wild they fly and feed in pairs. However, a few can be vicious. They chew anything in sight and theirs jaws are powerful, a fact which should remain foremost in your mind as you perform a physical examination.

Blue and Gold Macaw - one of the more intelligent and better talking macaws, although quite mischievous. Underparts from the neck to tail are yellow-gold; the crown, neck, back and tail are a rich blue, the forehead green, the bill black.

Scarlet Macaw - friendly, intelligent, and fairly good talkers. Brilliant red except for the wings, base of tail and its under parts, which are dark blue the wings below the shoulder are yellow with tint of green.

Green-winged Macaw - friendly, fairly good talkers. Similar to The Scarlet Macaw except for the green and blue on their wings.

Hyacinth Macaw - rare, expensive, boisterous with limited talking ability. Cobalt blue with a yellow eye ring, and a yellow bare streak at the base of the lower beak.

Military Macaw - easily tamed, moderate good talkers. Overall green with slight olive tinge on its back and wings; bluish tinge colors the back of the neck, and the forehead is red.

Severe Macaw - most easily obtained, dwarf macaw, quite a capable talker, gentle. Green with chestnut brown on the forehead, chin and borders of the bare cheek areas. 

1.2.2.1.4 Cockatoo (Kakatoe spp)

Size: 17-18 inches in length, originated from Australia. Easily distinguished from parrots by their relatively square tail and crest of elongated, pointed feathers. White is the common background color. Pastel overtones on the breast and tail feather. Affectionate.

The most common cockatoos are Leadbeater's cockatoo, the sulfur-crested cockatoo, and The Lemon-crested cockatoo.

1.2.2.1.5 Cockatial (Nymphicus hollandicus)

Next to the budgie, the cockatial is the most popular psittacine in captivity. Native of Australia. Size: 12 inches in length with a long tapering tail. The head has a long pointed crest. The body is soft gray. Adult male have a bright yellow face and a circular patch of orange on the checks. Adult females have only a slight trace of yellow on the face, and the circular patch on the cheek is a much duller orange than in the male.

Easy to breed, excellent pets, can be caged with other small birds, easy to tame.

1.2.2.1.6 Lovebird (Agapornis spp.)

Beautiful psittacine, originated

1.2.2.1.7 Lorikeet (Trichoglossus spps.)

Nectar eaters from Australia. Their plumage is a beautiful mixture of greens, blues, reds, and yellows. size: 10-11 inches, half of which is tail.

1.2.2.1.8 Conures (Statinga spp.)

Long tailed, small-medium size parrots from Central and South America. Beautiful bird.

1.2.2.2. PASSERINES (PERCLING BIRDS)

1.2.2.2.1 Canary (Serinis canarius)

The second most popular caged bird behind parakeet. It is a finch named after the Canary Islands. Greenishyellow birds with yellow breasts, stands 5 - 51/2 inches tall. The sexes are alike in appearance, life span is 6 - 1-5 years.

1.2.2.2.2 Finch (Poephila spp. and Lonchura spp.)

Several hundred species with world wide distribution. Domesticated forms: Gray, tang cream or buff. Wild form: Gray, 41/2 inches long.

The finch bill is red, the breast white, and the tail black. Males differ from females in that their checks are chestnut and their breasts finely barred black and white.

1.2.2.2.3 Talking Mynah (or Mynah) (Gracula religiosa)

A member of the starling family. Large black birds. Size:12-18 inches long. The bill and feet are yellow, a white patch on each wing, and the sexes are similar. They have no crop, they hop rather than walk. Life span: often exceeds 30 years. Originated from tropical Asia. Best talking birds around. 

1.2.2.3 PICIFORMES

1.2.2.3.1 Toucan (Ramphastos)

The Toc, Toucan and the Sulfur-breasted Toucan are the most common Piciformes in captivity. Beautifully colored with red, white, black, and green colors. The most striking feature is the huge, soft, light-weight orange bill with dark markings. Origin: Central and South America. Size: 16 inches. Male and females are alike. 

Toucans are very active, moving with jerky but precise movements. If frighten they often traumatize themselves in small cages.  

1.3 SIGNIFICANT ANATOMICAL DIFFERENCES BETWEEN BIRDS AND MAMMALS

1.4 EXTERNAL ANATOMY OF BIRDS

1.4.1 The head and beak

.The head supports the beak which is characteristic of birds. It is composed of the upper and lower jaws, each covered by a horny (keratinized) sheath. It grows constantly in many species of birds and is worn down accordingly by feeding, grooming, climbing, and purposeful rubbing on parts of the cage or a cattle fish bone. Shape of beak varies in different species of birds. Teeth are entirely lacking in the chicken. There are two small, elliptical openings, the nostrils or external nares, which pierce the upper mandible. There are a number of bristle-like feathers guarding each opening. Notice the fleshy comb on top of the head and the wattles below the jaw. The eyes are large and arranged for monofocal vision since one is on each side of the head. Each eye is provided with an upper lid lower lid, and nictitating membrane which is drawn across the eye from the anterior corner.

1.4.2 The Ear

The ear structure is evident externally only as the opening of the external auditory meatus on each side, which is just behind the eye and covered by feathers, with bristles guarding the opening.

1.4.3 The Trunk

The trunk is quite firm and rigid, divided into the thorax and abdomen. The appendages are attached to the trunk. The thorax bears the wings and the abdomen, the legs. Both of these pairs of appendages are specialized, the wings for flight and the legs for bipedaly locomotion on land. Notice the Z,-shaped position taken by the wing,. The upper arm is short and partly bound by the trunk. The forearm is longer and free.

1.4.4 The Uropygiym

The uropygium or tail supports a group of large quill feathers known as rectices.

Just anterior to the uropygium among the feathers on the dorsal side may be found a papilla or projection of the skin. This is the opening of the uropygial gland which secretes oil to be used in preening the feathers. The cloacal opening or anus is a aperture with thickened lips and oblong shape. It is located just ventral to the tail.

1.4.5 Feathers

The peculiar outgrows of the integument or skin of birds are feathers. They are primarily exoskeletal (derived from ectoderm), in their adult form.

(1) Type of feathers

The contour feathers -- Cover feathers, which forms the outline of the bird. It is composed of two general parts. the quill or calamus and the vane.

• Plumules or down feathers -- Feathers completely covered by contour feathers.
• Filoplumes -- Hair feather, which is bound between bases of the other feathers. It consist of a slender shaft.

(2) Functions of feather.

• Efficient body insulator, maintain high body temperature of 105
• - 109°F. Essential for flight, waterproofing protect birds from injury; sexual attraction. 

(3) Molting -- Feathers are dead structure after six weeks of age. 

Therefore it is a normal process for chickens to shed their feathers at 6 to 13 weeks and at maturity. Molting is also affected by following factors:

• Too Heavy Medication
• Changes in Feeding
• Outbreak of diseases 

Birds usually molt in the following order, the head feathers molt first, then neck, body (including breast, back, and abdomen).

Wing and Tail.

1.4.6 The Skin

The skin of the fowl is comparatively thin, consists of an outer thin epidermis and an underlying thicker dermis. In the areas which are covered with feathers, the epidermis is dry and covered with fine scales. Theses scales (danders) are constantly being shed and replaced as new skin tissue is formed. 

There is no sweat glands nor sebaceous glands, except uropygial or preen gland located at the base of the tail.

The scales on the shank and feet, the toe nails, the beak and feathers are modification of the epidermis, while the comb, wattles and earlobes are developments of the dermis.

There are few blood vessels in the skin, except comb and wattle. 

 

1.5 INTERNAL ANATOMY AND PHYSIOLOGY OF BIRDS

1.5.1 Skeletal System

The skeleton of the fowl is compact, light in weight and very strong. Many long bones are hollow, which helps to make them light; and many are fused together, forming very strong structures to which the large flight muscles are attached. Most bones are pneumatic, containing a pocket of air (a diverticulum of an airsac surrounded by bone which is thin hard and porcelain like in appearance).

1.5.1.1 Axial Skeleton:

Skull - Consists of cranial bones and facial bones. Fusion of bones taken place in adult birds, thus reducing the number.

1.5.1.2 Vertebral column

Consists of the following bones.

• Cervical - First joint with skull in atlas. Cervical bones are not fused, carried an S-shape. The neck is long and freely movable.
• Thoracic - Fused, to form a firm base for the attachment of the wing and its muscles.
• Lumbar - Sacral - fused.
• Coccygeal - tail bone. Pygostyle supports the tail feather,
• Sternum - the ribs and shoulder girdles are attached directly by ligaments no costochondral junction. Shape various in different species. Duck and geese are flat for floating purpose, However, in chickens, turkeys, the sternums are sharp.

1.5.1.3 Vertebral formula of some fowls.

C = Cervical, T = Thoracic, LS = Lumbar, - Sacral, CY = Coccygeal,

Chicken	C14	T7	LS14	CY 6-7
Turkey	C15	T7	LS14	CY 9-10
Duck	C14	T9	LS14	CY 7-8
Geese	C18	T9	LS14	CY 7-8
Pigeon	C12	T	LS14	CY 7-8
Swan	C18	T8	LS7	CY 4-6

1.5.1.4 Appendicular Skeleton

• (a) Pectoral girdle or shoulder girdle. Each half of this girdle consists of three bones.
  • Coracoid - Ties the shoulder girdle to the sternum, strongest bone in the group. 
  • Scapular (Shoulder blade) - Elongated, flattened bone, lies parallel to and against the vertebral column as well as resisting on the ribs.
  • Clavicle - (furculum) - A pair of well developed "wish boone", suspended from the shoulders.
• (b) Fore limb, wing
  •  Humerus - Arm
  • Radius, Ulna - the forear ulna is stronger and more posterior.
  • Carpal bones - Two, wrist.
  • Metacarpus - The metacarpals and other carpals are fused to form two long bones, the carpometacarpus. Phalanges - The digits, three in number, the first, second and third. The second digit is much the largest with the first digit, contains two phalanges while the third has but one phalanx.
  • Function of the forelimb - keep body balance and support flying.
• (c) Pelvic girdle - large and greatly fused or ankytosed.
  • Ilium - The largest of three bones of each side of the girdle, fused on the lumbar-sacral bone.
  • Ischium - Flat, large bone scietic foreman located. 
  • Pubis - A slender piece of bone.

  These three pieces of bones meet at acetabulum which constitute the hip joint. 

• (d) Hind limbs, legs.
  • Femur - Relatively short, articulated with the acetabulum.
  • Tibio-tarsal - Larger bone of the shank.
  • Fibula - Slender lateral bone of the shank, fused to the side of tibio-tarsal.
  • Patella - Knee cap, covers the knee joint.
  • Tarsometatarsus - A fusion of bones, the proximal tarsais being fused with the tibia and the distal row with the metatarsals.
  • Digits - Toes. There are: 2-3 in Ostrichs, 4-5 in chickens, 1 and 5 are posterior digits, the long toes is 3.
• (e) The tail is supported by a fiddle-shaped last vertebrae called pygostyle.
• (f) Total bones in Chickens:

 

SECTION	YOUNG	ADULT
Skull	23	4
Vertebral	42	24
Sternum	-	-
Ribs	14	14
Thoracic	24	24
Limb	-	-
Hind Limb	44	40

1.5.2 Musculature

The muscles comprise the greatest bulk of body and by their contraction produce movement and heat.

1.5.2.1 Breast muscles

• The two large breast muscles, attach to the sternum and the most important flight muscles which elevate and depress the humerus. This muscle weight as much as do all the rest of muscle put together. The pectoralis is also called superficial pectoral, responsible for the downstroke of the wing whereas the supracoracoides (deep pectoral muscle) is considerably smaller, is responsible for the upstroke.

1.5.2.2 Diaphragm

• Quite rudimentary. Does not form a partition between the thoracic and abdominal cavitates but separates the lungs from the viscera and is in contact with the ventral surface of the lung. There are muscle bundles in the coastal attachment.

1.5.2.3 Thoracic muscle

• Between adjacent ribs are external and internal intercostal muscles which act to pull the ribs forward, thus enlarging the thoracic cavity and aiding inspiration. The external intercostal muscles are better developed than the internal muscles. Respiration is brought about by contraction of abdominal and intercostal muscles while at rest and by the action of the pectoral muscles during flight.

1.5.2.4 Abductors

• 4. The leg abductors are very weak, predisposing birds to leg problems.

1.5.2.5 Gastrocnemia muscle

• Strong muscle at the back of the legs, allow the bird to roost.

1.5.3 Digestive System

The digestive system of birds has some very specialized organs and is quite different from that of monogastic mammals.

1.5.3.1 Beak

Horny, breaking up and gathering food and protection. Most birds use their lower beak, by raising and lowering the head, as a scoop for funneling food and water to the crop. Birds of prey do chop their food into small pieces and psittacines dehull or crack seeds with their beaks. Pigeons and finches are two domesticated pet birds which can suck.

1.5.3.2 Mouth parts

No teeth, lips and cheeks. The tongue is shaped like the barbed head of an arrow with the point directed forward. The barb-like projections at the back of the tongue serve the purpose of forcing the food toward the entrance to the gullet when the tongue is moved back and forth. In water fowl, the tongue is wider, softer and more flexible.

1.5.3.3 Pharynx

Common passage for food and air.

1.5.3.4 Esophagus (gullet)

Dorsal to trachea, passage way for foods.

1.5.3.5 Crop or ingluvius

An expandable organ, serves as storage site for ingested food which is awaiting digestion. It is located in the lower neck on the midline or slight]y to the left, outside of the body cavity.

Amylase enzyme which originated in the mouth, start working on starch in this organ. There are two kinds of movements in this organ. Forcing ingesta into the preventriculus. Hunger contraction began 30 to 45 minutes after eating, gradually increasing in frequency and vigor until in 5 to 6 hours they occurred in groups of 6-12 or more, separated by intervals of comparative rest of the crop. Crop is absent in geese and swans. In small passerines the crop is rudimentary while in gallinaceous birds it is very large. Besides storage food, the epithelial cells of the crop mucosa of some birds (pigeon) swell up and rupture producing a nutritious crop milk (pigeon milk) which the adults, both male and female, regurgitant to feed their young.

1.5.3.6 Proventriculu

True stomach with glandular secretions. Spindle shape, lumen is scarcely larger than that of the esophagus. Storage capacity is very limited. The stomach glands secrete gastric juice (Pepsin and hydrochloric acid). Fish-eating birds possess such potent enzymes that even bones are digested, while birds of prey, such as owls, cannot tolerate bones and regurgitate them.

1.5.3.7 Ventricle (gizzard)

oval, flattened from side to side, composed of two pairs of red, thick powerful muscles, covered internally with a crushing coarse feed. This process is aided by the presence of grit or gravel taken through the mouth. 

1.5.3.8 Small Intestine - Duodenum

The first section of the small intestine, a folded loop of about 5 inches long in mature chicken, and encloses the pancreas. It termination is marked by the pancreatic and bile ducts which pour their respective juices into the intestine at very nearly the same point. Duodenum acts like a stomach of a mammal, gastric digestion is active. Pancreatic juice contains,

• (l) Trypsin - protein,
• (2) lipase - fat,
• (3) amylase carbohydrate,
• (4) bile - digestion of fat, contains amylase (the amyloytic action is smaller than pancreatic juice).

Jejunum-ileum - No line of demarcation between the two parts. They are supported by a mesentery and bounded by airsac which separate them from abdominal wall. Length about 4 feet long in mature chicken, (intestinal juice secreted enzymes included: erepsin protein, sucrose, lactose and maltose). Absorption begins in this section of small intestine. The digestion and absorptive process in the small intestine are extremely rapid; digestion and absorption can be completed in three hours.

Yolk sac diverticulum - a remnant of the yolk stalk between jejunum and Merckel's ileum, which is transformed into a lymphoepithelial tissue.

1.5.3.9 Ceca or one cecum

Two blind pouches, about 4-6 inches long in chicken function unknown. Cecum empties its contain twice daily, (usually 7 am. and pm.). Manure in the par is brown in color. Absent in pigeons, hawks, eagles and parrots,

Colon-rectum - Very short, about 5 inches. Function is to absorb water from urine and intestinal tract. No enzyme secretion or digestion takes place here.

1.5.3.10 Cloaca or Vent

A chamber common to digestive and urogenital systems. There are three openings: 

Coprodaellm - stores feces Urodaeum - collects urine Protodaeum - tile exterior opening of the cloaca (vent), the duct of the bursa of Fabricius enters just cranial to protodaeum. The protodaeum turns inside out during mating of both sexes, permitting the transfer of semen.

1.5.3.11 Liver

The largest gland of the body, consists of two lobes, dark reddish-brown in color (yellow in baby chicks, due to fat deposit, replaced by blood in 3-4 weeks). The outer surface is convex and smooth. The visceral surface is irregularly concave molded to fit the adjacent organs. The right lobe is larger: On its visceral surface the gall bladder is absent in the following fowls:

• Ostrich,
• pigeon and
• guinea fowl.

1.5.3.12 Pancreas

• Long, thin, light-colored organ, occupies the space formed by the loop of the duodenum. 
• Function - Secretes pancreatic juice and insulin

1.5.3.13 The PHI of intestine

Gizzard content is most acidic (PH2-3.5). Relatively alkaline in small intestine (PH5.5-6.8). However, intestinal contents never reach alkaline state.

1.5.4 Respiratory System

• 1. Nostril - Non-movable, covered by flap or valve to keep the water out. Chickens clean its nose by using the feather or with its feet. Nasal salt gland occur in marine birds, act as second kidney.
• 2. Posterior nares.
• 3. Pharynx
• 4. Anterior larynx: The larynx is not guarded by an epiglottis, devoid of thyroid cartilage and vocal cords. The laryngeal skeleton consists of paired arytenoid cartilages, a trough shaped cricoid cartilage, and a nodular procricoid cartilage.
• 5. Trachea - The windpipe is a flexible tube, kept open by cartilaginous rings in its wall, a lined by stratified squamous epithelium. It connects the larynx with the syrinx and lies to the left of the esophagus. It consists of about 90-120 rings in chicken, ossified in water fowls.
•  
• 6. Posterior larynx, syrinx - a structure peculiar to birds, is the vocal organ formed by modified cartilages of the trachea or bronchi, or the combination of the two, with associated muscles and membranes. Trachea divides into two bronchi here. The voice of the fowl is produced in true syrinx. The airsacs are also necessary to voice production, for if the cervical airsacs are punctured no sounds would come from the fowl.
• 7. Bronchi - Leading into either lung from the syrinx is a primary bronchus which has both an extra and intrapulmonary portion. The primary bronchus enters the craniomedial surface of the lung and course caudolaterally.
• 8. Bronchio - A bronchus passes through the entire length of each lung and connects finally with the abdominal airsac. This makes the airsac important reservoirs of inspiration and expiration, there are no blind ends in the bronchial system. The air passages are continuous, with many anastomoses. It is probably that air moves more or less continuously through the system instead of in and out. Airsacs connect with the bronchi and with the cavities of many of the bones.
• 9. Airsacs. There are eight.
  • (l) Cervical, 2, one right, one left. Extend to the neck as far as 3rd. cervical, as low as 4th rib.
  • (2) Interclavicula, one. Has several pouches extend to the wing.
  • (3) Anterior thoracic. From the base of the lung to sterum.
  • (4) Posterior thoracic. Paried, bounded by the pulmonary and thoraco-abdominal diaphragms and do not have connections with air cavities of bones.
  • (5) Abdominal airsacs. Paired, the largest of the air sacs, surrounding the kidney to the head of femur and to the muscles of the thigh.

  Functions of the airsacs: Help in respiration, Posterior thoracic and abdominal airsacs help in expiration.; Regulate body temperature instead of sweat glands.; Reservoir for air.; Cushion the kidney.; Aid in spermatogenesis in the males and allow the sperm live in the female for longer time, by cooling mechanism.

• 10. Respiration process: Breathing is effected by the action of the intercostal and abdominal muscle of the bird. Passage of the air through the respiratory system is a 2 cycle process requiring 2 inspirations and 2 expirations for a breath of air to enter and leave the bird. Inspired air moves from the trachea through the primary and secondary bronchi into the candal airsacs, never reaching the air capillaries of the lung. On expiration this stored air moves cranially through the anastomosing parabronchi of the lungs and into the air capillaries where O2/CO2 exchange occurs. On the next inspiration the air moves from the lungs forward to the cranial airsacs. With the next expiration the air passes from the cranial airsacs into the bronchi and trachea and out of the bird.

1.5.5 Urinary system

1.5.5.1 Urinary system:

Kidneys, each of the two chicken kidneys has 3 lobes about 3 inches long, brownish, highly vascular, attached to the vertebral column (lumbarsacral region) from the vertebral end of the sixth rib to well back into the iliac fossa. They are homogeneous in cross section and it is difficult to distinguish between cortex and medulla.

Blood is supplied to the kidney from the aorta as well as from the renal portal veins. Blood from the large intestine pelvic region, and pelvic limbs is brought to the kidney by the caudomesenteric, pelvic, and isciatic veins. Clinically footpad and hock infections or enteritis may quickly result in renal damage.

1.5.5.2 Ureter:

A ureter runs from the candal lobe of each kidney to the urodeum of the cloaca. Uric acid is the end product of protein metabolism in birds and is excreted by an unknown renal tubular mechanism. Sulfonamides utilize a similar tubular excretory mechanism. Their use in birds must be extremely judicious, especially if there is any evidence of renal damage.

1.5.5.3 Urinary bladder: None, except Ostrich. 

1.5.5.4 Cloaca:

The urine is discharged into the cloaca which serves as a urinary bladder. Normal urine of fowls is a cream-colored, thick, tenacious mucoid material containing an abundance of urates which readily settle out forming a semi-solid mass. (Sodium urate).

1.5.5.5 Vent:

Other excretory organs: In addition to kidney function for maintaining water balance, many birds possess nasal salt excreting glands which are highly efficient sodium excretors as well as osmoregulators. Some marine birds excrete more salt via the nasal gland then through the kidneys

1.5.6 Reproductive system

1.5.6.1 Female

Ovary

In early embryonic life there were two gonads in the female, normally only the left one develops, the right being found functionless rudiment. The left ovary is attached to the dorsal wall close to the left kidney. When in functional condition it appears as a cluster of many yellow vascular spheres which vary in size which is not visible to the unaided eye. In the ovary of a non-laying hen, the ova are all small perhaps none being more than l/4 inch in diameter. An adult female can lay eggs without fertilization or mating. Obviously these eggs will not hatch.

Oviduct

The oviduct is a convoluted tube which in the laying hen, fills a large part of the left half of the abdominal cavity. The oviduct may be divided into five parts, primarily on the basis of function:

• Funnel, infundibulum - Fertilization
• Magnum - Secretes thick White
• Isthmus - Secretes shell membrane
• Uterus, shell gland - Shell is formed
• Vagina - Passage

1.5.6.2 Male

Male Reproduction System composed of testes, conducting ducts, a portion of the cloaca and accessory reproductive organs.

Testes

There are two, posterior to lungs and anterior to kidneys attached to the dorsal wall of the abdominal cavity. In the mature fowl, they are light yellow in color, not necessarily of equal size, close to the junction of iliac vein from posterior vena cava.

Epididymis

Small bulb part of the testis.

Vas deferens

Runs beside the ureter on its way to the cloaca, into which it opens through a small papilla.

Papilla

Serve as an intermittent organ, located on the dorsal wall of cloaca.

Rudimentary copulatory organ

It has no connection with the vas deferens, and is located on the ventral portion of the fold between the urodaeum and the protodeum of male chicks is a very small, shiny or glistening projection, it is by ever the cloaca to expose this rudimentary organ that day old chicks are sorted into pullets and cockerels.

Ducks have a blind tube helps the emen to flow down, erected by lymph flow.

1.5.7 Nervous System

Quite similar to mammals. Consists of two principle divisions, the cerebrospinal and the sympathetic.

1.5.7.1 Central nervous system:

Brain, the cerebrum is the largest part of the brain and, divided into two hemispheres. The cerebellum and medulla oblongata are considerably reduced. In contrast to mammal the surface of the fowl's brain is smooth.

1.5.7.2 Peripheral nervous system:

Cranial nerves, with 12 cranial nerves as in mammal plexus in the wings. Sciatic nerve - Large double nerve trunk which arises from the spinal cord by 4 or 5 heads dorsal to the kidney, It is buried in the muscles of the leg and is easily found cutting lengthwise through the inside thigh muscles.

1.5.8 Sense Organs

1.5.8.1 The eye

• Excellent eye sight, one of the best sense organ in chicken, eyes located laterally on the two sides of the head, vision is wide (300).

1.5.8.2 Ear

• Do not have external ear, have opening only, with excellent internal ear, good hearing senses.

1.5.8.3 Taste

• Taste papillae are absent. However, chicken can differentiate chemical tastes.

1.5.8.4 Smell

• Poorly developed.

 

1.5.9 Circulatory System:

1.5.9.1 Heart

The heart lies just in front of and partly between two lobes of the liver. It is concical in form and is surrounded by pericardium, Avian heart consist of 4 chambers. No ducts arteriosum or ligamentum arteriosum in chicken. Plaques of cartilage in aorta at semi-lunar values and sometimes wall of common pulmonary artery.

1.5.9.2 Blood vessels

• Jugular vein - bleed chicken in killing.
• Brachial-subclavin - For bleeding.
• Metatarsal vein - In the shank, also for bleeding.
• Renal portal system - the presence of a valve at the bifurcation of the external iliac vein and the renal vein with renal portal blood goes to tubules, and renal artery blood goes to glomeruli.

1.5.9.3 Blood contains

3/4 liquid, 1/4 solid, approximately 5% of body weight.

1.5.9.4 Collection of blood specimen.

Blood samples can be collected from the wing vein (brachial) - punch a hole in the vein with a beveled needle and collect the blood in capillary tubes.

1.5.9.5 Hemoglobin

Denington and Lucas.

• - 0.02ml whole blood collected into a Sahli hemoglobin pipette, and mixed with 10 ml of 0.4% concentrated ammonium hydroxide solution (in distilled water).
• - After one hour, 0.36 ml. con. HCL was added, and the tube was inverted several times.
• - After 15 minutes, the optical density was read at wavelength of 410 u.
• - The hemoglobin value (g of hemoglobin per dl) was determined by comparison with a special graph from samples of human blood known to have 15.4 g of hemoglobin per dl.

 

Chicken- male	11.76
Female	9.11
Budgies	11.9

 

Data of hemoglobin values for other birds. Refer to page 27l, Diseases of Cage and Aviary Birds.

1.5.9.6 Hematocrit

The one test offering more information than any other procedure packed cell volume is an indication of anemia and dehydration. Though examination of the buffy coat is not adequate as a determination of the WBC, high white blood cell counts are indicated by a buffy coat in excess of 2 mm. The color of the serum is also significant. An icteric serum sample is easily recognized by its yellow color. Lipemia is demonstrated by the milky appearance of the serum, and can be obesity related. The normal PCV in avian species is 35% - 50%. In collecting blood, heparinized capillary tubes are used. The tubes are centrifuged in a microhematocrit centrifuge for 3 minutes.

1.5.9.7 Hematology

Avian erythrocytes and thrombocytes are nucleated, and blood clots very quickly. Since all blood cells of birds are nucleated, the methods commonly used for counting mammalina blood cells can not be applied. Numbers of erythrocytes and leukocytes varies in different species of fowl.

Red cell count - Blood was collected directly into a red cell pipette which had been rinsed in heparin solution (10 mg heparin sodium/ml) to prevent coagulation of blood. After filling the pipette to the 0.5 ml mark, Natt and Herrick's solution was added until the 101 mark was reached Pipettes were then agitated for 30 second with a pipette shaker. Five of the secondary squares of the central primary square of counting chamber were counted. Reference on RBC about various species of birds can be obtained from 271-286 of Diseases of Cage and Aviary Birds.

Natt and Herrick's diluting fluid

NaCl	3.88g
Na2S04	2.50
Na2HPO4 12H2O	2.91 g
KH2PO4	0.25 g
Forrnalin (37%)	7.50 g
Methyl violet 2b	0.10 g

Dissolve in distilled water and dilute to total volume of 1,000 ml in a volumetric flask. Filter.

Birds	Sex	Erythrocytes	Hemoglobin
Chicken	M	3.23	11.76
-	F	2.72	9.11
Pigeon	M	3.228	15.97
-	F	3.096	14.72
Duck	F	3.06	15.6

(The count of erythrocytes and value for hemoglobin are usually higher in male birds than in female birds. This is believed due to the influence of androgen).

*Expressed in millions per mm

+Expressed in grams per 100 cc.

 

White cell count - with avian blood, it is impossible to selectively destroy the red cells and leave only the white cells, as can be done with mammals. This is mainly because avian red cells and thrombocytes are nucleated.

By diluting 5 parts of Natt and Herrick's solution with 4 parts of distilled water for WBC count. Red cell pipettes were used with the diluted Natt and Herrick solution to make a 1:200 dilution. Heterophils are the easiest white cells to recognize in the counting chamber because of their large dark granules, but it is difficult to recognize the other white cells in the counting chamber and to distinguish them from immature RBC and thrombocytes. A two steps method is used. Count the total number of heterophils in all squares of 1 side of the counting chamber, then multiply by 222 to derive the number of heterophils per cu mm. If 8 heterophils were counted and the differential count showed that 40% of the WBC were heterophils, then the total number of WBC per cu mm was 8 X 222 X 100/40, or 4440. Ref. for total WBC and differential count can be obtained on p. 290 298, Diseases of Cage and Aviary Birds.

Birds	Sex	Thrombocytes	Leukocytes
Chicken	M	25.4	19.8
-	F	26.5	19.8
Duck	-	30.7	23.4
Pigeon a.m.	-	-	13.05
Pigeon p.m.	-	-	18.55
Tukey	-	-	-

*Expressed in thousands per mm3

Differential count - Films of avian blood require a longer staining than those of mammalian blood. Slides are stained for 5 minutes with Wright's stain and distilled water is then applied for another 5 minutes. One hundred white cells are counted in each blood film.

DIFFERENTIAL WHITE BLOOD CELL COUNT (PERCENT)

Birds	Sex	Lymphocytes	Heterophils
Chicken	M	59.1	27.2
-	F	64.6	22.8
Duck	-	61.7	24.3
Pigeon a.m.	-	65.6	23.0
Pigeon p.m.	-	47.8	42.8
Tukey	-	50.6	43.4

 

Birds	Eosinophils	Basophils	Mon
Chicken	1.9	1.7	10.2
-	1.9	1.7	8.9
Duck	2.1	1.5	10.8
Pigeon a.m.	2.2	2.6	6.6
Pigeon p.m.	1.9	2.4	-
Tukey	0.9	3.2	-

1.5.9.8 Blood cell morphology

Heterophils

Presence of many rod or spindle shaped acidophilic crystalline granules in a clear colorless cytoplasm. The nucleus is lobulated, 2 or 3.

Eosinophils

Size similar to heterophils, granules spherical with dull red in color. Cytoplasm have a faint bluish-gray tint. The nucleus is often bilobed, and the chromatin appears to be stained richer blue than in the heterophil's nucleus.

Basophils

The nucleus is usually marked by the basophilic granules in the cells. The cytoplasm is clear and colorless.

Lymphocytes

Constitute the majority of leukcocytes in the blood of the fowl. There is a wide range in the size and shape of these cells. The cytoplasm is weakly basophilic. The nucleus usually round, the chromatin is rather coarse and blocky.

Monocytes

Large cells with relatively more cytoplasm than the large lymphocytes. The cytoplasm has a bluegray tint. The nucleus is rather irregular in outlines, the chromatin having the tendency to appear in the form of strands rather than blocks.

Thrombocytes

Smallest cells in the fowl blood. It is oval with a nearly round nucleus in the center of cytoplasm. There are two or three small bright red staining granules at one pole of the cells.

5. Thrombocyte count

count the thrombocytes in the central and 1 other ruled area of a counting chamber. Each are equaled 1 sq. mm.

1.5.9.9 Blood Chemistry

Blood clotting time for birds is about 5 - 6 minutes.

- Total plasma protein

After a hematocrit was performed, the capillary tube is broken and plasma allowed to flow on a refractometer. Values of 3.5 to 6 gm/lOOml are considered normal. Birds are considered hypoproteinemic with value below 3 gm/lOOml and with values below 2.25 mg/lOOml a grave prognosis must be given. Birds suffering from hypothermia have values below 3.5 mg/100 ml.

- Blood glucose

Blood glucose levels can be determined with 0.05 ml of whole blood, using a micromethod based on the Somegyi-Nelson method. Value determined with a reagent strip test agreed fairly closely with the micromethod (Dextrostix, Ames Co, Inc., Elkhart, Ind.)

- Normal glucose values are approximately 200 - 500 mg/dl.

Birds demonstrating level below 150 mg/dl should be supplemented with dextrose orally or parenterally. Birds with values lower than 70 mg/dl usually die.

Glucose Level

Glucose levels can drop within 24 hours in small birds and two to three days in large birds due to starvation and disease.

- Hypoglycemia

Acute hepatitis (Pacheco's disease), chronic, end stage liver disease.

- Hyperglycemia

Diabetes mellitus cannot be diagnosed on the basis of a single elevated blood sugar. A second sample should be taken in 24 hours to eliminate the possibility of a transient hyperglycemia. If value are still elevated or continue to elevate after the second sampling, insulin therapy should be instituted. (Diabetic birds range from 700 mg/dl to as high as 1300 mg/dl). Hyperglycemic birds spill glucose in their urine, therefore, to determine urine sugar will aid in evaluation of hyperglycemic state.

- Blood uric acid and urea

The primary nitrogen breakdown product of protein metabolism in birds is uric acid, the determination is valuable in the evaluation of kidney function. Sample required - 10 microliter. Normal value usually range from 2-15 mg/dl. Birds in renal failure usually have level exceeding 20 mg/dl.

- In addition to renal failure, uric acid can be elevated in visceral and/or articular gout.

- BUN - not a useful text in birds.

The primary waste product of protein metabolism in birds is uric acid and not urea. Birds with renal failure do not have elevated BUNS. Amazon parrots 5-18 mg/dl.

- Serum calcium

sample required 10 microliter Amazon parrots - 8.9 - 10.5 mg/dl. calcium levels can be low in some cases of nutritional secondary hyperparathyroidism, (Deficiency of Ca or Vit. D). Birds with low level may convulse, especially if excited. Low Ca levels can be seen in some cases of renal failure.

- SGOT

Sample required - 10 microliters often elevated in liver disease in which necrosis is found. Level above 230 R-F units/ml (Reitman - Frankel) are considered abnormal, but with significant hepatic necrosis, values as high as 2,000 to 3,000 units are not uncommon.

1.5.10 Lymphatic System

Lymph glands: fowls do not have many regional lymph nodes. However, cecal tonsil, thymus, bursa of Fabricius and spleen are composed of lymphoid tissues. Numerous small lymph nodules are present in various parts of the avian body. Especially in submucosa of the intestinal tract and bronchi. Lymph nodes are present in cervical and caudal region of water fowls.

Lymphatics:

consists of a closed capillary network and layer collecting vessels which return lymph or tissue fluid from all parts of the body to the venous system. Lymphatics in the bird terminate principally by two thoracic ducts which enter the right and left jugular veins or the cranial vena cava by several orifices. Lymphatics also carry absorbed fat from the intestine to the thoracic duct. Associated with lymphatic vessels are cell-producing lymph follicles, lymph nodes, thymus glands, spleen, the bursa of Fabricius and egg yolk diverticulum.

1.5.11 Regulatory System

1.5.11.1 Pituitary gland (hypophysis)

• Non paired attached to the ventral surface of the brain stem caudal to the optic chiasma.
• Anterior lobe - ACTH: Adrenocorticotrophic hormones. Thyrotrophic hormones. Follicles stimulating hormone, prolactin (broodiness).
• Posterior lobe hormone: The function is to stimulate rise of arterial blood pressure. Antldiuretic effect. Oxytocin action, stimulation of muscle coat of the uterus. Responsible for oviposition.

1.5.11.2 Thymus

Paired along the jugular vein of the neck, degenerated at about the time of laying. Associated with immunogenesis. The lymphoid cells in the paracortical area (thymic dependent region) are responsible for cell mediated immunity.

1.5.11.3 Thyroid

Paired, inside the thoracic cavity, next to the jugular vein. Feeding of large doses of either fresh or desiccated thyroid is followed by rapid molting. Thyroxine also affects the color and form of feathers.

1.5.11.4 Parathyroid

Two or three pairs, posterior to the thyroid. Formation of egg shell is partially under the control of hormones secreted by the parathyroid glands.

1.5.11.5 Adrenal

Anterior to the kidneys. Regulate carbohydrate metabolism.

1.5.11.6 Gonads

Ovary and tests. Responsible for secondary sex appearance.

1.5.11.7 Pancreas

Produced insulin and trypsin.

1.5.11.8 Bursa of Fabricius

Dorsal to cloaca. Necessarily for the production of antibodies. Disappear at the time of laying.

1.5.11.9 Spleen

Lies dorsal to the liver, Round in shape.

Body temperature.

Birds	Temperature
Goose	105F
Turkey	105.4
Chicken	105-107
Pigeon	105.8-111.5
Average	105-107 is normal 109+ fever