EGGS FOR INCUBATION AND EATINGThe 4-H Poultry Committee: Jenny Mountford, Steve Hucks, Dawn Baggett-Stuckey, Carly Smith, and for more information contact:Mickey Hallmahall@clemson.edu864-885-2197

Objectives• Learn about the anatomy and physiology of the chicken’s reproductive tract• Learn how the egg is formed• Learn about natural and artificial incubation of fertile eggs and brooding of

chicks• Learn the parts of the egg• Learn about the nutritional value of eating eggs• Learn about the functional properties of eggs

Reproductive Tract

The reproductive tracts of the chicken lie across the back of the bird.

The female of birds determine the sex of the offspring which is the opposite of mammals

Female Reproductive Tract

Actual Photo

Female Reproductive TractnThe female reproductive tract is made up of two main parts:1. Ovary2. Oviduct (Only Left is Functional, the right is rudimentary and was lost to

make the bird lighter for flight) Develops rapidly after 16 weeks of age in a female chicken

• Infundibulum (Funnel) first part of the Oviduct• Magnum largest part of the oviduct where the albumen (egg white) is laid down• Isthmus (Gives the Shell its Shape) – narrowing of the oviduct where the shell

membranes are laid down• Shell Gland the egg stays here 20+ hours and lays down concentric layers of shell

made up of Calcium carbonate• Vagina here the egg is flipped so that it will come out large end first, up until this time it

was coming down the oviduct pointed end first

Ovary2000 Visible Ova in an immature hen

Only 250 – 500 reach maturity & are ovulated released from the ovaryHierarchy of Follicles where biggest ova leave theOvary first. Look at the picture, which one will bereleased first?

Highly Vascularized – lots of blood flow for the absorption of nutrients from the feedOvulation – release of the most matureova from the ovary which Occurs along the Suture Line

This one will be released first

Infundibulum (The Funnel)Purpose of the Funnel• Ova from ovary is released and picked up by the Funnel the first part of the

oviduct• The egg stays here 18 Minutes• This is where Fertilization takes place• Internal Ovulator – Funnel fails to pick up the ova and the ova drops into the

body cavity which can result in peritonitis or inflammation and infection of the body cavity if it is NOT Reabsorbed within 24 hrs

• Also the First Layer of Albumen (egg white) is produced here

Magnum and IsthmusMAGNUM

Largest Portion of the OviductMajority of the Albumen (Egg White) Formed HereSome Calcium Secretion Occurs HereEgg stays here 2-3 Hours

ISTHMUSInner & Outer Shell Membranes are Formed HereIt is a narrowing of the oviductThese shell membranes give the egg its shapeEgg stays here 1 Hour and 14 min.Shell Formation is Initiated in the lower end of the Isthmus

Shell GlandThe shell is laid down herePlumping the egg prior to calcification of shell with Calcium carbonatePlumping – egg takes up salts and 15g of fluid into the albumenCalcification – initiated by ovulation or by neuroendocrine (brain and hormone) factors control & coordinate both ovulation & calcium secretion. Egg stays here 18 – 20+Hours Calcification – Many Layers of Calcium carbonate are laid down to form the shellPigments – deposited 3hrs – 0.5 hr before oviposition (egg laying)

Protoporphyrin is the pigment to make brown shelled eggsBiliverdin is the pigment to make blue or green shelled eggs

VaginaThe egg gets flipped here so that it will be laid large end first. Up until this time the egg has been coming down the oviduct pointed end firstHelps with the expulsion of the egg and is made of smooth muscleUterovaginal Glands are found in the vagina– to store sperm

Sperm can last in these glands for 7 – 14 days in Chicken before fertilizationSperm can last greater than 21 days in a turkey before fertilizationFill Sequentially - w/o mixing so that w/ successive inseminations, sperm from the latest insemination is most likely to fertilize an ovum first which is important to keep in mind when wanting to change males for breeding

Male Reproductive System

Testis one always larger than the otherInternal on birdWhere sperm is made to fertilize the egg

Semineferous TubulesInside the testisProduce sperm

EpididymisCarry the semen containing sperm to the outside of the bird’s body via the Vent for fertilization of the hen’s eggs

Fertilization of Hen’s Eggs

The male gets on the back of the female and the vent of the male and the vent of the female come together and semen is inserted in the hen’s vagina

Anatomy of the Egg

The True EggFERTILIZATION• Spermatazoon penetrate the blastodisc of the ovum Fertilizing it • The blastodisc becomes the BLASTODERM or TRUE EGG• Cell Division or embryonic development takes place until egg is laid• Development subsides until incubation by hen or incubator

Factors Needed for Breeder Birds to Produce Fertile Eggs• Light – a minimum of 12-14 hours of light are required for chickens to

lay eggs as well as 8 hours of darkness for rest• Proper Diet for breeding birds • Proper Number of Females to Males for fertile eggs• Ambient Temperatures – the temperature in the coop or outside if too hot

fertility drops • Egg Storage for fertile eggs if setting eggs in the incubator you want the

eggs stored in a cool DRY place about 50 – 55F to prevent any sweating• At 72F or “Physiological Zero” the germ will begin development

• Egg Washing of Fertile Eggs – if eggs are so dirty they need to be washed then they probably should NOT be set to begin with but…

Handling & Washing of Fertile Eggs• For incubation• Eggs too dirty should not be set• Eggs can be washed before setting use soft brush or sponge with mild

soap• Make sure eggs are completely dry before setting• Make sure eggs have come to room temperature before setting

• If storing fertile eggs to be set• Store at 55F • Bring out of cool dry room and let eggs come to room temperature.• Do NOT store eggs for more than 5 days, otherwise viability of the germ

goes down and so does hatchability

The Developing EmbryoThe development of the chicken embryo takes 21 days Physiological Zero: 72F is the temperature where the embryo begins to developIncubation Temperature: 99.5F – 100.5F

Still air incubator should be 100.5F (No fan for air movement)Forced air incubator should be 99.5F (Fan for air movement)

Overheating is more of a problemRunning the incubator @105F for 30 min. will seriously damage embryos

UnderheatingRunning incubator @ 90F for 3-4 hrs will slow metabolic rate also not a good idea

Artificial Incubation• The incubator like mother hen provides heat, humidity, and turning of the

eggs• Start incubator at least 3 days before setting eggs • Check incubator with two calibrated thermometers (EVEN IF IT IS

COMPUTER CONTROLLED!!!!!!)• Place incubator in a well-ventilated room• Make sure incubator has plenty of ventilation – oxygen coming in since the

developing embryos in the eggs are breathing giving off carbon dioxide• Need at least 21% Oxygen why we have to pump in oxygen to incubators in

Denver, the mile high city• Is the automatic turner working• Consider a surge protector

Turning EggsTurning• Prevents blastoderm from migrating through albumen and sticking to shell

membrane• Turn eggs 3 -5 times daily for first 18 days• Last 3 days of incubation do NOT turn and do NOT move the incubator• Do not open or move incubator after day 18

Chicks are in hatching positionMaintain desirable humidity

Humidity• Relative Humidity for first 18 days: 60%• Last 3 days: RH = 70%

Condensation on eggs during last 3 days of incubation indicate adequate moisture If room where the incubator is placed is cold more condensation will form on the eggs

• Room where incubator is placed is important too• Too much moisture prevents evaporation & results in decreased hatch• Too little moisture results in too much evaporation & chicks stick to shell

• To Increase humidity• Atomizer spray• Sponge in water pan• Check the air cell size by candling

Candling EggsCandling Eggs - is looking inside the fertile egg to determine if the embryo is developing properlyCandling can be done in a dark room with a flashlight or a candling light specifically for this purpose can be purchasedCandling should be done on eggs placed in the incubator at day 7, 13, and at day 18 when the turning of the fertile egg is stopped.By day 7, you should be able to see the heart beat and blood vessels forming and whether the egg was fertile Day 13 is critical in embryonic development to determine if it is still developingAt Day 18, the embryos should be continuing to develop but the turner will be stopped

Candling

Day 7 Day 13

Embryonic Development• With proper heat embryo develops• Various cells in the embryo acquire specific structures• They Form: ectoderm, mesoderm, endoderm• Ectoderm: skin, feathers, beak, toes, nervous system, lens and retina of the

eye, linings of mouth and vent• Mesoderm: bone, muscle, blood, reproductive and excretory organs• Endoderm: linings of digestive tract, respiratory and secretory organs

From Egg to Chick• Requires respiration, excretion, nutrition, & protection• Embryo uses “extraembryonic” membranes for these functions

• Yolk sac: The embryo digests and absorbs yolk for sustenance• Amnion: Protective cushion surrounding embryo during development• Chorion: Contains amnion & yolk sac, fuses with allantois (‘allen toys”)

to bring capillaries of allantois in direct contact with the shell membrane, allowing for calcium reabsorption from the shell

• Allantois:• Embryonic respiratory organ• Receives excretions from embryonic kidneys• Absorbs albumen for protein for embryo• Absorb Calcium from the shell for structure

Hatching• Days 18-21

• Remainder of yolk drawn into embryo’s body• Chick’s head under right wing• Tip of beak toward air cell (large end of egg)• Egg tooth forced through air cell with neck muscles• Chick takes its first breath

• Takes anywhere from 4 – 12 hours to hatch out• Does not come out wrapped in swaddling clothes and laying in a

manger….comes out wet and tired• Egg tooth lost in a few days that it used to break through the shell

Brooding• Brood in a COMPLETELY separate room from where incubation and

hatching take place• Heat for warmth• Feed: can live for 2-3 days after hatch on absorbed yolk material• Water• Protection from predators, dampness• Fresh air• No exposure to drafts

Brooding• Set up Brooder unit at least 3 days before expected hatch (1 square foot/5

chicks)• Set temperature at 95F measured at 1 inch above floor (height of the chick’s

back) for 1st week• Reduce by 5F for each subsequent week until room temperature is reached

(70F)• Floor should have absorbent litter no slippery floor• Feed 18- 22% Protein diet chick starter• Water should be clean and available at all times

BROODER RING• 18 inches high made ofCardboard• Feeders• Waterers w/marbles to prevent chicksFrom getting in waterersAnd getting wet and cold• Heat lamp above the brooderRing

Feeder

Feeder

Feeder

Feeder

water

water

water

water

Clean & Sanitize Incubator• To prevent any cross-contamination between batches• Remove all debris from incubator• Wipe down trays with cloth containing Quaternary ammonium compounds,

Clorox, or hydrogen peroxide• Let the incubator dry completely by setting it in the sun• Avoid getting cleaning solutions on electrical parts

Just Plain Eating Eggs….I don’t think so!What is the purpose of the egg?• We just learned the purpose is reproduction• It is a biological entity that is designed to protect itself… the germ the

center of reproduction!• Why it is so difficult to “make a rotten egg!”

• The egg has many layers and structures which protect it:• Shell, • Shell membranes, • The many layers of Albumen (egg white), • The proteins of the albumen, • The composition of the yolk and its being in the center of the egg

The Egg

Chalaza

Thick Albumen

Yolk

Outer Thin Albumen

Chalaza

What’s the First Line of Defense for the Egg?THE SHELL• Physical Defense

Its Structure98.2% Calcium0.9% Magnesium for shell hardness (outer layer)0.9% Phosphorous (Phosphate)(outer layer)

• Chemical DefenseCuticle: foamy layer of protein that gets drawn into the pores to seal them when the egg is laidMatrix of Protein & Spherical Masses (1)part Protein to (50) parts of Calcium carbonate which are interwoven to make the shell very strong

What’s the Next Line of Physical Defense?The Shell Membranes• The Outer Shell Membrane is attached to shell and has 6 Layers• Inner Shell Membrane has 3 Layers made up of

Polysaccharide – SugarsProteins (Keratins)Vary in thickness Offers great resistance

• The Inner and Outer shell membranes separate at the large end of the egg and form the air cell. When an egg is first laid it does not have an air cell

• The air cell gets larger as the egg ages. So by candling an egg you can see the air cell and how large it has become to determine if it is an old or newly laid egg

The Next Layer of DefenseThe Albumen which offers both physical and chemical defenses• Protein system with ovomucin that offers “stickiness” preventing bacteria

from getting through to the yolk• pH = 9.5 which is very basic and not inviting to bacteria• Has other specific proteins which can lyse bacterial cell walls or prevent

bacteria from growing again to protect the yolk or germ if the egg was fertilized–Outer Thin (23.3%)–Outer Thick (57.3%)–Inner Thin (16.8%)–Chalaziferous (2.7%)

Layers of Albumen• Outer thick albumen supports the yolk and is made up of protein and water• Outer thin albumen is made up of protein • Inner thin albumen is found inside the outer thick albumen and is made up

of primarily water.• Chalaziferous layer wraps the yolk like a piece of taffy and holds the yolk in

the center of the egg keeping it from moving up and down and from side to side and is very heat stable so it is the last layer of protein to coagulate when heating an egg

The Yolk is No Joke, It Too Offers Protection• The yolk is in the center of the egg held there by the Chalaza which wraps it

like a piece of taffy. One of the Chalazae is going clockwise and the other counter-clockwise to keep the yolk from moving up and down and from side to side so it stays in the center of the egg

• The next protection the yolk has is it is surrounded by the Vitelline Membrane which has two layers which were formed in the ovary. Its Strength decreases w/ age of the bird

• What is the Yolk Made of:• Yolk Solids 50%• Protein + Lipid• 46% Water which Migrates from Albumen to Yolk

Eating Egg Handling and Cleaning• Pick up eggs in coop at least 2 times/day

• Collect on a washable container (plastic or ceramic)• In warmer weather collect eggs more often

• Washing Eggs For Eating • Luke warm water• Soft brush or sponge• Mild soap (Ivory dish soap)• DRY completely• Place in clean carton• Mark cartons with name, address & phone number• Don’t reuse cartons for biosecurity reasons

Why We Add Eggs to Other Foods?Because of their “Functional Properties”The Functional Properties of Eggs are:• Contributing Nutrients: Nutritional Value• Color• Flavor• Crystallization• Coagulation• Foaming• Emulsification

Contributing Nutrients Nutritional ValueWhole Egg (Large)

72 Calories6.6% Protein6.0% Fat

Albumen19 Calories3.88% ProteinNo Fat

Yolk54 Calories2.74 % Protein5.8% Fat

Eggs are Nutritious providing quality protein, are low in Calories and help us feel full

Eggs Add Color and Flavor to Other FoodsPigments found in the Yolk• Xanthophyll• Lutein• Zeaxanthin

Foods in which we use eggs for color• Baked Goods• Noodles• Ice Cream• Custards• Sauces

Crystallization ControlEgg White is used for Crystallization in Candies

Incorporates Air + Egg White + SugarBinds Water in the Egg WhiteBy Binding Water this Prevents Syneresis –the leaking of water from the crystal and makes it viscous and stable

Coagulation• Coagulation is going from a Fluid state (Sol) to Solid/semi-solid

state (Gel) which is what happens when we cook an egg• Both the Egg White & Yolk undergo coagulation• Coagulation is affected by: Temperature, dilution, salt, sugar,

acid/base• Coagulation is important for making:

• Cakes & Confections• Meringues• Omelets• Souffles• Sponge Cakes

FoamingFoaming is the beating of the egg white to incorporate air into a liquid mixtureFactors Affecting Foam Formation• Method of Beating electric beaters vs. hand mixing • Blending • Temperature too warm can breakdown the stable foam• Water too much can weaken the foam and cause it to weep• Sugar will help stabilize the foam• Salt can help stabilize the foam• Egg Yolk will breakdown the foam because of the fat• Oil will breakdown the foam because of the fat

EmulsionEmulsion is mixing of oil (O) and water (W) An O/W emulsion is where a little bit of oil is mixed with a greater amount of waterA W/O emulsion is a little bit of water mixed with a greater amount of oil like with margarineThe Egg Yolk itself is an O/W Emulsion Egg Yolk as an Emulsifying Agent helps breakdown the barrier between the oil and water such as in salad dressings so they won’t separate

Use and Function of Eggs in FoodsFood Product Functional PropertyCakes, Angel

Cakes Sponge

Candy

Custards

Egg White Meringue

Salad Dressing, Mayonnaise

Foaming & CoagulationFlavorFoaming, & Coagulation of whole eggColor of egg yolk

Inhibition of Crystals

Coagulation & Flavor

Coagulation

Emulsion

Sample QuestionsCloverbudWhich of the following is NOT a functional property of Eggs?a. Reproductionb. Emulsionc. Coagulationd. CrystallizationWhat is the Largest portion of the hen’s reproductive tract?a. Isthmusb. Magnumc. Infundibulumd. Shell Gland

Sample QuestionsJuniorWhat portion of the hen’s reproductive does the egg spend the most time?a. Infundibulumb. Magnumc. Shell Glandd. IsthmusWhat pigments in the yolk are responsible for providing color from the egg?a. Biliverdinb. Xanthophyllc. Luteind. B & C

Sample QuestionsSeniorWhich of the following is NOT a layer of albumen?a. Chalazaeb. Outer Thick Albumenc. Vitelline Membraned. Inner Thin AlbumenWhat is the embryonic respiratory organ called?a. Chorionb. Allantoisc. Amniond. Yolk Sac