dr fares elkhayat - avian biology

7/29/2019 Dr Fares ElKhayat - Avian Biology

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Revision of Poultry BiologyBirds & Poultry

PoultryBirdsDomesticated birds including chickens, turkeys,

ducks, geese, quail, pigeon & ostrich.Both domesticated & undomesticated species of class

Aves. About 10000 avian species in 27 orders.N.B Some author classifies RABBITS with poultry although they are mammals.

Aims of poultry production:

1-Meat production commercial broilers" Hubbard, Ross, Coob, Avian 48 and Arboplus" & cross-bred

broilers "Saso breed". In addition Turkeys, ducks, ostriches and quails are reared for meat production.

48

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2-Table egg production commercial layers as Hi Lyne, Hisex, Bovans and Lohmann..

3-Fertile egg production Breeders "Breeder of Hubbard, Ross, Coob 500 & 700, Avian 48 and

Arboplus" & Saso breed"

.4-Feather production ostrich.

5-Fun Pheasants, Sparrows, Parrot and pigeon.

The differences between commercial layers & breeders.

BreedersCommercial layersCriteriaFertile eggTable eggAimEssentialsNot presentMale

Deep litter onlyDeep litter or cagesSystem of housingNot less than 3 kgNot more than 2 kgWeight of hen

Not less than 80 gmNot more than 60 gmWeight of eggNot less than 150 gmNot more than 120 gmAmount of feed/hen/day

LowerHigherFeed intensity Not more than 180 eggNot less than 300 eggEgg productivity/yearAbout 70 weeks.About 60 weeks.Life Span

Classic with IBD, Reo, CIA.Classic without IBD, Reo, CIA.Vaccination schedule

Mention the poultry terms:

Broilers: reared till 6-7 wk old either six (2 kg), Tender andeasy to cook, 800 million in Egypt.

Roaster: Older & slightly larger than abroiler.

Capon: Castrated chicken at 5-7 month old weighs about

4 kgs.

Chick: Young chickens.

Poult: young turkeys. Pullet: semi-mature chickens.Duckling: young ducks. Gosling: Young geese.Squab: Young pigeon. Tom (Gobbler): matures turkey.


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Hen: mature chicken, turkey, duck & geese. Drake: mature male duck.Gander: adult male goose. Gaggle: group of geese.

Avian unique CharacteristicsI-Anatomical characteristics:1-Feathers + no sweat glands + sparse distribution of sebaceous glands + uropygial or preen or oil bag orgland that is well developed in aquatic birds, in addition to the scales onto legs and feets.

2-Modified forelimbs into wings for flying in most birds and modified hind limbs for walking, swimmingor perching.

3-Birds have no teeth and the lips are replaced by horny beaks of different shapes according to species. Itis modified for prehension of feeds.

4-Presence of fused skeleton in certain area of vertebral column e.g. synsacrum "fusion of the 14th and15th vertebrae of the caudal region of the vertebral column".

5-The presence of air sacs which will be discussed later. They have very important functions in avian

respiration.

6-Avian species have no diaphragm and the thoracic, abdominal & pelvic cavities are fused in onecelomic cavity. The fusion of body cavities in birds facilitates the transmission of infections in-betweenthe visceral organs.

7-Avian species have no urinary bladder and urethra and the two ureters originate from the two kidneysand open directly in the cloaca.

8-Avian species are characterized by the presence of the cloaca "universal sac having 4 openings; thecoprodium (opening of intestine), the urodium (opening of ureters), the proctodeum (opening of vasdeference in male and the left oviduct in female) and the opening of bursa of Fabricius.

9-Avian females have 2 ovaries & 2 oviducts but the right ones are atrophied and un-functional while theleft ones are the only active ovary and oviduct.

10-Avian species have no lymph nodes except for ducks and geese in which there are two primitivelymph nodes, each of which is located along the side of the femur.

II-Physiological characteristics:1-Avian digestive system is of low physical limitation, so, the avian feeds should be nutritionallyconcentrated, having all nutrients and easily digested and absorbed.

2-The activity, number of heart beats, respiratory rhythm, metabolic and growth rates of avian species arehigher than those of the mammals, so the nutritive requirements of the former are higher than in the latter.

3-Avian R.B.Cs are nucleated, avian neutrophilis are modified to hetrophils and avian blood platelets aretrue cells "thrombocytes". Avian antibodies are only three types "IgG, IgM and IgA".

Avian R.B.CsThrombocytesMHC-I.

4-The avian species are warm-blooded animals i.e. constant body temperature is whatever the ambienttemperature.


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5-The avian species are oviparous i.e. reproduction via internal fertilization and external brooding of eggs.

6-Avian species are uricotelic i.e. their end product of protein metabolism is uric acid.

N.B. Animal species are classified according to their end product of protein metabolism into: Ureatelic"all mammals except for ruminant and Dalmatian dog"; Allantolotelic "ruminant and Dalmatian dog";Amoniatelic "Fish" and Uricotelic "Poultry. Avian species are uricotelic i.e. their end product of protein

metabolism is uric acid.

External Avian AnatomySkin: it is thinner and more delicate than that of mammals. The color of the skin varies according tospecies, breed, age and diet.

Feathers: cover almost the entire surface of bird. Grow from feather follicles, which are organized intofeather tracts. Feather tracts are named according to the structure they are associated with e.g. thefemoral feather tract is on the thigh, which contains the femur. It insulates and protects skin from getting

wet or injured. It also helps birds to fly or glide. Newly hatched chicks have down . Feathers begingrowing in a few days and are grown by 4-6 weeks. Second feather growth at 2-3 months. Final feathergrowth occurs at sexual maturity. Feather patterns and colors vary with breeds and varieties. Malefeathers have pointed tips; female feathers have rounded ends.

Molting: Hens molt (lose feathers) once a year when they stop laying eggs. Most birds molt and replacetheir feathers by growing new ones.

Comb & wattles are external structures on the head of birds and are largely ornamental . The sizeand color of them are correlated with the gonad development and secretion of the sex hormones. The red

color of the comb and wattles is attributed to the high vascularity of the dermis covering them. They havedifferent characteristic features in male vs. female birds, and among different poultry species. Snoods andwhiskers (beards) are the external structures in turkeys' equivalent to the comb and wattles.

Uropygial, preen, oil gland oroil bag: itis the only significant gland of the skin that is located dorsallynear the tip of tail. It is present in all birds but well-developed in water fowls. In the chicken, two lobesdrain through a median nipple-like papilla. Its function is somewhat uncertain but preening birds take oilfrom it and apply it to their feathers. It also has a function in vitamin D and calcium metabolism.


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Avian Skelton: the avian skeleton has the following characteristics:-Essentially modified for flight: Supports flight muscles (pectoral girdle, keel/sternum) to withstand thestress of flight.-The forelimbs are modified into two wings.-There are fewer and fused digits.-It has a reduced mass.

- It has Fused bones adding rigidity e.g. synsacrum which resulted from the fusion of the 14th and 15thvertebrae of the caudal region of the vertebral column.

- It has pneumatic bones : major bones hollow "Not completely hollow" with struts, airspaces connected to respiratory system. Major bones of body are pneumatic.

Lack teeth- lightweight beak.

Beak: it is composed of hard-keratinized epidermal tissue. This rostral structure forms part of the upperand lower jaws. The beak functions much like the lips and teeth of mammals.

Debeaking is the removal of approximately one-third of the upper and lower level. In some cases, onlythe upper beak is removed. Debeaking is used in poultry industry to prevent cannibalism.

Medullary bone forms in hens during egg production, providing calcium.


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The sternum, keel orbreast bone is a single large bone on the ventral surface of the body. Ribs aredivided into two types. The vertebral ribs are those that originate from the vertebral column. The sternalribs are those that originate from the sternum (keel, breast bone).

Birds have no teeth: However, they can digest food 6 times faster than mammals. How does it happen?There are two essential adaptations, the crop and the two stomach system. The Crop is a storage unit for

easy gluttony and escape. The two stomachs are the upper (Proventriculus) and the lower (Gizzard). Theupper adds the enzymes and the lower crunches the feed.

Wings, Feet and Legs: Chickens legs have scales; most chickens have 3-4 toes with claws used inscratching. Domestic chickens have wings but cannot fly well or at all. Lighter birds can fly shortdistances and clear fairly high fences.

Chicken MusclesDark meat: Red fibers with more myoglobin (oxygen carrying protein) for greater aerobic metabolism

e.g. Leg muscles.White meat: White fibers containing very little myoglobin e.g. breast meat.

The avian digestive system:Mouth & pharynx: tongue, beak, choanal cleft, no soft palate, salivary glands and taste buds.


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Mouth secretions: Mucus (lubricant), amylase in some species and adhesive saliva.

Esophagus: long, contains mucus glands.

Crop (ingluvies)...Variable in size and shape

Produce crop milk in pigeon and doves under the influence of prolactin hormone.

Esophagus and cropsecretions: Mucus and if amylase is secreted in saliva there may be CHO digestionin crop.

Proventriculus: fusiform, variable relative size. It has chief cells and mucus cells. The secretions are HCland pepsin "Chief cells" and mucus "Mucus cells".

Gizzard (ventriculus)-Two pairs of muscles "thin and thick". It has koilin "protein lining whose color is related to bile

pigments". It is responsible for the mechanical digestion. It has special digestive functions (grit - smallbits of stone retained in the gizzard).

-Small intestine: duodenal loop, jejunum and ileum. Shorter than mammals. Chemical or enzymaticdigestion and absorption. The intestinal Secretions are amylase, saccharidases, peptidases, lipase, maltase,isomaltase Enterokinase and Sucrase.

-Liver: relatively large, left and right ducts and gall bladder may or may not be present. The liversecretions -bile "Emulsifies fats, contain lipase and activates pancreatic lipase".

-Pancreas: lies in duodenal loop, has three ducts. The secretions arebicarbonate, chymotrypsin, trypsinand amylase.

-Ceca: single, paired or absent, short, junction of ileum and colon, ilieocecal valves, fermentation andfiber digestion.

Colon or rectum: short, ilieocecal junction to cloaca and water balance

Cloaca: universal sac having 4 openings; the coprodium (opening of intestine), the urodium (opening ofureters), the proctodeum (opening of vas deference in male and the left oviduct in female) and the

opening of bursa of Fabricius. It is responsible for excretion, mineral and water balance.


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:. -

-Low physical limitation of digestive system.

) -38(.

.

:1-Mechanical digestionMastication

. ...

2-digestion Microbial

. ...3-Chemical or enzymatic digestion

.

.. ......

.

Summary of Physiology of DigestionG.I Tract Region Enzyme

(secretion)Substrate End Product pH

Mouth Saliva Lubricates and softens food --Crop Mucus Lubricates and softens food 4.5

Proventriculus &gizzard

HCIPepsin

Lowers stomach pH 2.5Protein Polypeptides

Duodenum Trypsin,

Chymotrypsin &ElastasesCarboxy-petidases

Collagenase

Proteins, Peptones

& PeptidesPeptidesCollagen

Peptones, Peptides

& amino acidsPeptides & aminoacids

Peptides

6.0 to 6.8

Jejunum Peptidases Peptides Dipeptides & 5.8 to 6.6


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Polynucleotidase Nucleic acids amino acidsMononucleotides

Avian Respiratory System:Very efficient, unidirectional biphasic air flow. Presence of air sacs "Average of 9 in number", Servevariety of functions and lack muscular diaphragm. Small lungs (2% of body volume) connected to largeair sacs (~10X larger).

Respiration: Smallest birds have fastest breathing rates. Air sacs make the body lighter for flight and arepart of the respiratory system. Birds are susceptible to respiratory diseases that spread beyond the lungsinto the abdominal cavity and bones.

Pneumatic bone: discussed before. .

The differences between respiratory system of poultry and mammals.

Criteria Respiratory system "poultry" Respiratory system "mammals"lung Non tidal Tidal

Air sacs present notRespiration Unidirectional bi-phasic Unidirectional uni-phasic

Air Sacs in Poultry: The air sacs are named according to their location:1. Cervical air sac: in the neck.2. Interclavicular air sac: between the clavicle.3. Anterior thoracic air sac: fore portion of the chest below and in contact with the lungs.4. Posterior thoracic air sac: hind portion of the chest (thorax), behind the lungs in the area between thelungs and the reproductive organs.

5. Abdominal air sac: behind the last rib backward to the pelvic cavity. Air sacs form in the embryo inpairs but some fuse forming a single sac. Not all classes of poultry have the same number of air sacsbecause different species fuse different pairs of air sacs.


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The following are the air sac specifications for different species of poultry: Air sac diverticula are out-branchings of the air sacs. The cervical air sacs have diverticula into vertebrae of the neck, back and ribs.The interclavicular air sacs have diverticula into the breastbones and the bones of the shoulder girdle aswell as around the shoulder joint. The thoracic air sacs have no diverticula. The abdominal air sacs investthe abdominal viscera and extend into the kidney crypts. They have diverticula around the hip joints.

Duck air sacs Turkey air sacs Chicken air sacs

Cervical 1 pair Cervical Fused Cervical 1 Pair Interclavicular Fused Interclavicular 1 pair Interclavicular Fused

Anterior thoracic 1 pair Thoracic 1 pair Anterior Thoracic 1 pair Posterior thoracic 1 pair Abdominal 1 pair Posterior Thoracic 1 pair

Abdominal 1 pair Abdominal 1 pair Abdominal 1 pair

The avian cardiovascular System:Circulation: A chicken heart is four chambered. Chicken heart beat are about 200-300 times/minute.Smallest birds have highest heart rates and relatively larger hearts than larger birds. 1.5-2 X larger than in

comparable mammals. Maintain higher metabolism. Heart size increases with altitude for same species.There are separate systemic, pulmonary circulations. Homeotherms.

Blood Pressure: Slightly higher than mammals' Aortic ruptures may occur in turkeys.

Aorta: it is the main vascular trunk in birds and aortic arch is the curvature of aorta after leaving theheart which is weak in nature leading to aortic rupture in heavy weight turkeys.

The avian Urinary system:The urinary system of the chicken does not contain a urinary bladder. There are two trilobed kidneys, oneon each side of the ventral surface of the vertebral column. This pair of kidneys is embedded in the deep

bony crypts of the pelvic and synsacral area of the skeleton. Ureters carry the urinary waste to the cloaca.


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The uric acid is discharged into the cloaca and excreted with the feces. The white pasty material inchicken droppings is considered to be urinary system excretion. Birds excrete their nitrogen waste as uricacid, whereas mammals excrete it in the form of urea.

Excretion: Kidneys & salt glands, Kidneys similar to mammal kidneys but 2X as large (relative), morerapid metabolism and not as efficient at removing salt need for salt glands.

Kidneys produce uric acid rather than urea. Requires less water (not as toxic as urea).

Uric acid works well in dry climates, conserves weight, Water not needed in large quantities, Wastesdumped into cloaca (no urinary bladder), mixed with feces, forms white paste with dark lumps.

Salt glands in head concentrate salt 3-5X that in blood discharge through nostrils especially active inmarine birds. There is no urinary bladder; urethra and the ureters are open directly in the cloaca.

Define with examples: Ureatelic, allantolotelic, uricotelic & amoniatelic: Discussed before

The avian ReproductionDifferent from mammals in: oviparous and not viviparous.

Male reproductive anatomy: Paired testes grow during breeding season; shrink otherwise, up to 200-300X difference in size between seasons. Left testis is slightly larger than right. Vas deferens is wavytubes.

Mature sperm collect until transferred. End nearest cloaca may swell to serve as storage sac. Copulatoryorgan "phallus" present in more primitive birds e.g. flightless ratites, galliformes, ducks & geese, erectile,grooved structure used to guide sperm into females cloaca during copulation.

Birds lacking feature just press cloacal openings together.


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Sperm development "spermatogenesis": High body temperature causes problems. Sperm cells cantdevelop at normal body temperatures. Alternatives: Develop at night when body temperature may drop.Delay final development until storage in cooler sac or pouch near cloaca.

.

Sperm Output: Millions to billions/copulation.

Sperm viability: Sperm cells remain in oviduct 2-3 wks after mating. At the 10th day 50% ability and atthe 19th day 15% ability.

Female reproductive anatomy: Left sided ovary and oviduct are the only active one but the right ovaryand oviduct atrophied.

Ovary: Ovary may contain thousands of ovarian follicles. Only few per year mature into ova. Rapidgrowth through addition of fat, protein food (yolk) probably from liver

Oviduct has five parts: Infundibulum Funnel, Magnum, Isthmus, Uterus and Vagina.

Infundibulum Funnel: Receives the yolk from the ovary. Sperm cells received from the rooster arestored here. It captures released ova, 2 ova released simultaneously produce double-yoked egg. Ovumspends ~20 minutes here in chicken.

Magnum: The largest region that secretes layers of albumen (egg-white). It takes 3 hrs for the thick whiteto be placed around the yolk in the magnum. Ovum spends 4 hrs here in chicken.


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Isthmus: the yolk and thick white then moves to the Isthmus, 2 shell membranes are added; Producesshell membranes. Flexible keratin, Ovum spends 1.25 hrs here in chicken.

Uterus: thin white colored producing the outer shell of egg, egg remains in the uterus about 20 hrs inchicken. Shell gland produces calcium carbonate shell. Pigment glands apply colors.

Vagina: after the egg is completed it moves to the vagina. Stays in the vagina for a short time and is then

expelled from the hens' body. Lined with mucous glands and muscular to aid egg-laying. Ovum spendsvery brief time here in chicken - just passing through.

One egg takes 25-27 hours for a chicken to produce one egg.

Hormones, light and nutritional programs influencing in egg production.

Fertilization Process: Male places the sperm into the female oviduct. Male papillae deposits sperm incloacal wall of female. Sperm move up the oviduct to the funnel where the egg is fertilized "at theampoula". Sperm cells remain in oviduct 2-3 wks after mating. Sperm have full fertilizing ability for

about 6 days after then ability of sperm to fertilize egg decreased. After yolk is fertilized it moves throughthe tract where the rest of the egg is added. Egg is laid - embryo grows inside the shell "Oviparous".

Incubation: keeping eggs at right temperature and humidity for hatching. Hen does this by sitting oneggs. Commercial hatcheries use mechanical incubators. Incubation of chickens is 21 days. Temperature38-39 C. Relative humidity 60% for the first 18 days. RH 70% for the last 3 days. Eggs are turned twicedaily for the first 15 days. Keeps the embryo from sticking to the inside of the shell. Provide a smallamount of oxygen.

The avian Eyes:

The eyes should be clear with dark black pupils surrounded by a colored iris. The color of the iris varieswith the breed and age of the bird, but in general is steel-grey in chicks and poults. In adult broilers,layers, and broiler breeders the iris is yellow-orange; but brown in adult turkeys.

The avian Ears:The ear in a bird is covered with fine feathers and is a small opening located on the side of the head. Theeye should be a bright yellow-orange in color and free of discharges.

The avian nervous system


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The avian body temperature:Normal for chickens are 41-42 C. Chickens are comfortable up to 25 C with 65% relative humidity. Birdskeep cool through the comb and by respiration panting and spreading their wings when too hot. Heatmanagement is more important for chicks than for older birds.

.

The avian life span:Fast heartbeat and high rate of metabolism limits life span. Chickens living to 10-15 years are the exception.Broiler chickens go to slaughter at a very early age about 7 wks. Commercial egg producers replace birds atabout 60 wk of age. Commercial breeders' producers replace birds at about 65-70 wk of age.

Serous & mucous membranes and differences between them.Serous membranes are the covering while the mucous membranes are the lining membranes. Mucousmembranes contain mucous or goblet cells while serous do not. Serous membranes are not suffering fromcatarrhal inflammation.

Examples of serous membranes are: pericardium, pleura, meanings, peritoneum, Glisson's capsule ofliver, synovial sheath and periostum.

Examples of mucous membranes are: mucous membrane lining the canalized systems "digestive,respiratory, urinary and reproductive".

Comparison of scientific terms to common poultry plant terms:

Scientific Term Plant TermUropygial gland Oil gland, preen gland, oil bag

Stifle joint Knee jointEsophagus Gullet, goozleIngluvies Crop, craw


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Cloacal bursa (Bursa of Fabricius) Rosebud, flower Ceca Blind guts

Trachea WindpipeSyrinx Voice boxLungs Lights

Pericardium Heart sacTibia and fibula Drumstick

Femur thigh bone ThighPubis Pin bone

Clavicles (fused) WishboneSternum keel Breast bone

Fused metacarpals Wing tipRadius and ulna Wing portion

Humerus Peg leg

Avian behavior: Chickens have a well-developed social order (peck order) and birds at the bottom maybecome culls if there is insufficient feed or water space. Close confinement of birds in cages mayaggravate this problem. If birds are mixed, considerable fighting to re-establish the peck order may occur.Temperament is a breed characteristic. Leghorns are more flighty than White Rocks. Birds arestructurally very different from mammals, and nowhere is this difference so striking as it is in thearrangements of their digestive systems. The evolutionary lineage of modern birds is in dispute, but onewidely held theory, for which there is some considerable support, holds that they're more or less directdescendants of the dinosaurs. As you might expect, therefore, there's not much similarity to the typicalmammalian pattern; furthermore, the avian digestive tract is suited to the peculiarities of bird life. Thecentral fact of being a bird is that everyone wants to eat you. With a few notable exceptions, birds are onnearly every predator's menu. Consequently, their anatomy reflects adaptations for evasion and escape.

To be able to "eat and run" (or "eat and fly") has real selective value, so birds have evolved a digestivesystem that permits them to "eat now, digest later," after they get away from whatever is chasing them.

:1-Small scale production:

20. %

2-Semi-intensive production:

70. %

3-production = Fully Integrated systems Intensive = Mass..

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dr fares elkhayat - avian biology

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