incubating eggs

8/6/2019 Incubating Eggs

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Incubating)

Chick~n Eggs

Incubating eggs artificially is an old art dlltingback to seveNI thousand years ago when theChinese and Egyptians developed artificialmethods. Theirs were crude compared with currentmammoth incubators which hold from a lewthousand up to 100,000 or more eggs in which thetemperature, humidity, ventilation, and turningare controlled automatically.Watching the embryo develop inside an egg isone olMture's mirtlCles.

Poultry Science Unit 3) Cooperative Extension Service Kansas State University Manhattan


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Hatching EggsSecuring Fertile Eggs

A hen mated with a rooster produces fertileeggs when the male's sperm unites with the ovum ofthe hen. Contact your local hatchery or county Ex-tension agent for sources of fertile eggs.

Care of Hatching EggsBefore IncubationThe chick's structural development beginssoon after fertilization. The hen lays the egg-ap-proximately 24 to 26 hours after conception. Thecells continue to divide as the egg travels down theoviduct of the hen. After the egg is laid, cell divisionceases whenever the temperature of the egg's con-.tents drops below80F. Store hatching eggs at tem-peratures between SS to 60~F. and a relativehumidity of 80 to 90 percent. For best results, in-cubate eggswithin seven,days after they are laid.

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Selecting Hatching EggsNot all eggs laid are suitable for hatching.Selecting eggs carefully is important for two rea-sons: the physical characteristics of the egg may in-fluence hatchability and many defects in eggs areinheritable. Factors to consider when selecting eggsfor hatching are size, shell quality, shape, andcleanliness.Size. Best hatchability is obtained from eggsweighing between 23 and 27. ounces per dozen.Double-yolked eggs rarely hatch.Shell quality. Eggs with thin or porous shellslose moisture too rapidly during incubation and areapt to be broken during turning.Shape. Within reasonable limits, egg shapedoes not affect hatchability. Do not select extremelyround, slender, or misshapen eggs.Cleanllneu. Dirty eggs hatch poorly and mayintroduce disease into the incubator.

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Operating the IncubatorDeveloping a fertile egg successfully dependsnot only on a plentiful supply of all food nutrientsessential for growth, but also on the environment ofthe egg during incubation. Give careful considera-tion to proper temperature, humidity, ventilation,and turning ..The recommendations apply specifi-cally to the type of incubator illustrated in "Con-struction of 'a Small Display Incubator," 4-H 138b.In most cases they also will apply to all types ofsmall still-air (no fan) incubators. ' .'

Records.Three times daiI~ record the temperature,turnIng of the eggs, adjusting the thermostat, andinteresting observations during the incubationperiod. Take the readings before you open the in-cubator to tum !~e eggs.See page 8 for a suggested form.

. Testing the IncubatorThe incubator should not be in direct 'sunlightand not subject to drafts and extremes of tempera-ture.Pretest the incubator. Operate it for at least 24hours with only water in the moisture pan. Thisallows you to adjust the temperature controls prop-erly. Regulate the temperature by turning the ad-justment screw which extends through the back ofthe incubator.

TemperatureNatural movements of air currents distributeheat and ventilate a still-air incubator. Maintainthe temperature at 102 to 103F. The bulb of thethermometer should be level with, but not touch-ing, the tops of the eggs.With the kind of controls commonly used insmall incubators, you will observe some fluctuationin temperatures. Do not be alarmed. The tem-perature can vary from 99 to 104F. with no harm-ful effects, if the temperature does not remain atthese extremes for long.Overheating is much more critical than un-derheating. Prolonged overheating will accelerategrowth and lower the percent of hatchability. Oper-ating a still-air incubator at 104 to 10soF. for theentire incubation will kill nearly all the embryos.Underheating slows down embryonic growth.

HumidityAvoid excessive drying of the egg because itcauses the chick to stick to the shell: adequate

moisture is mandatory. Yet, too much moisture inthe incubator prevents normal evaporation anddecreases hatching .. The problem usually is toomuch ventilation and not enough moisture in asmall still-air incubator ~To determine the moisture content of the air,make a cloth wick, wet it,and place one end overthe base of a thermometer. Wait five minutes, thencheck 'the reading of the thermometer.. It should3


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read between 85 to 90of. This is called the wet bulbreading and is determined by the rate watetevaporates in the incubator. Maintain a wet bulbreading between 8S and 90F. (SOto 65 percentrelative humidity) at all times.During the last three days, while the chicks arehatching, the wet bulb reading should be nearer90of. Put water in a cookie pan on the bottom ofthe incubator to provide moisture. Increase thehumidity by putting a sponge in the water pan, bysprinkling eggs with warm water, and by reducingventilation. Check the water level daily.Two other methods to determine moisture lossare candling the eggs and weighing the eggs.

CandlingAs incubation progresses, the air cell of theegg becomes larger and deeper because of themoisture lost bythe egg.You can candle the eggs to determine moisturelost. To candle, hold the egg in front of a stronglight in a darkened room. The light rays penetratethe egg and make it possible to observe the egg'scontents. .You can construct a simple, cheap egg candlerfrom an oatmeal box, tin can, or similar object. Cuta one-inch hole in the side of the box or can. Obtainan extension cord and mount a 60-watt bulb insidethe candler.To candle the egg, hold the large end in frontof the light, rotate it gently, observe the contents,

and record the depth of the air cell.Number each egg set. At the 7th, 14th, and18th days of incubation, candle eggs and comparethe air cells with your first depth.Do not keep the eggs out of the incubator formore than three to five minutes. Removing the eggsfrom the incubator for turning and observing doesnot harm the eggs if they are not allowed to cool ex-cessively. Excessive cooling slows down the chick'sdevelopment. The degree of delay depends on thedegree of cooling.Enter your results on page 6.

Determining Fertil.ityBy candling, you can determine the fertility ofincubating eggs after four or five days of in-cubation. What you will be able to see will dependupon your knowledge of the egg's structure andwhether the egg is fertile.As you hold a fertile ~gg in front of the can-dling light, you will see a small dark spot in the cen-

ter of the egg with a network of blood vesselsbranching out from it. This is the developing em-bryo. If the egg is infertile, the egg contents will ap-pear clear or devoid of any evidence of develop-mente Eggs showing "rings or streaks of blood"contain embryos that have died early in the in-cubation period.

WeighingAnother way to determine moisture lost is toweigh each egg at the 7th, 14th, and 18th day of in-cubation. By simple calculations you can determinethe percentage of the original weight lost. This lossmainly represents moisture. An egg should loseabout 10 percent of its original weight for the bestresults.

VentilationTo develop properly as a living organism. theembryo requires an ample supply of oxygen. Also.poisonous carbon dioxide must be removed for theembryo to survive.The incubator illustrated in Unit 2 has smallholes in the walls for ventilation. The holes at eachend of the incubator, between the level of the eggsand water pan, are inlets. Two outlets are providednear the top of the incubator. Restrict both outletsby pasting tape over half of the hole.When the first chick has hatched and emergescompletely, remove the tape from both outlets to in-crease the air flow.

Turning the EggsFor normal growth, tum the eggs at least threetimes each day. This prevents the embryo fromsticking to the shell membrane. An odd number ofturns per day is important because an even numberof turns allows the eggs to remain in the sameposition for a long time each night. You do notneed to tum the eggs after the 14th day of in-cubation.Mark the date on each egg to record when theegg was set and indicate that the egg has beenturned.You may use an egg carton to hold the eggs.Results usually are better if you place the eggsdirectly on the wire tray. Under no circumstancesshould the small end be higher than the large end.Change the position of the eggs in th~ incubator asthey are turned to eliminate the effects of possibletemperature variations inside the incubator.

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Eggs During HatchingOn the 18th day, remove eggs from the in-cubator and place crinoline or cheesecloth over thewire tray. Replace the eggs. After the 18th day, donot open the incubator unless necessary. Should itbe necessary to add water, add warm water(HOOF.).Remove the chicks after they have dried off. Ifeverything has operated properly, the chicks shouldbe dried and fluffed out by 21~ days after the eggswere set.

Why EggsFail to Hatch

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One or several factors may be involved wheneggs fail to hatch. Incubation temperature is too high or toolow. Humidity is too low during incubation.When the relative humidity is below 60 percent, thechicks may start to emerge from the shell on theregular hatch date, but then become stuck in theshell, unable to get out. Eggs have not been tumed properly. Eggs were held too long or were under im-proper conditions before incubation.Incubation periods for different species ofbirds are:Chickens:21 daysTurkeys: 28 daysDucks: 28 daysQuail (Bobwhite):

22.daysPea fowl: 26-28 days

Geese: 30 daysPheasants: 2S daysPigeons: 18 daysQuail (Cotumix):18_days

Factors that Influence HatchabilityCertain factors influence hatchability. In allthree experiments, you should number the eggsbefore setting. The appropriate tables are on pages6 through 10 to record results in each experiment.

TurningPlace a setting of eggs in the incubator. Tumhalf of the eggs three times per day for the first 14days. Do not tum the others.

EggPositionIncubate half of a setting of eggs with thesmall end higher than the large end throughout theincubation period.

Shell PorositySet two dozen normal eggs and two dozen eggssealed by dipping in mineral oil.

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Determining Moisture LossM ETHOD 1

Name __Address ~-------Name of C lub _Name of Community Leader _Name of Project Leader _

RemarksEgg Number 7 days 14 days 20 days

123456789101112131415161718192021222324252627282930

Indicate how air cell depth of individual egg compares with normal air cell.

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Determining Moisture LossMETHOD 2

Weight at Weight at Amount of PercentEgg Number Time of Setting 18th day Weight Loss Moisture Loss1234567891011121314151617181920212223242S2627282930

Answer the following questions:a. What was the average percentage lost during this period?b. What was the maximum and minimum percentage lost in individual eggs? _c. Explain these variations.

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Incubation DataDate Time Room Temp. Temp. Humidity Remarks

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Incubated eggs must be turned at least three times each day. Good results are obtained wheeggs are turned first thing in the morning, again at noon, and the last thing at night.Record time, temperature, and any unusual events, infertile eggs, and dead embryos.

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Determining Fertility and Hatchability) Fertility Hatchability

No. Eggs Set Date No. Fertile % Fertile No. Hatched % Hatched

E xp lain yo ur results.

Effect of Turning on Hatchability*Number Hatched % Hatchabi Iity

No. Eggs Set Turned Not Turned Turned Not Turned

* Based on fertile eggs only.E xplain your resu lts.

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Effect of Egg Position on H atcha bility*Number Hatched % Hatchability

No. Eggs Set Normal Abnormal Normal Abnormal

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* Based on fertile eggs only .. Explain your results.

E ffect of Shell Porosity on H a tchability*Number Hatched % Hatchability

No. Eggs Set Normal Sealed Normal Sealed

* Based on fertile eggs only.E xplain your resu lts.

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Albert W. AdamsProfessorAnimal Sciences and IndustryMarlon E. JacksonExtension EconomistPoultry Marketing and Production

COOPERATIVE EXTENSION SERVICE, MANBATI'AN, KANSAS4-HI38c February 1979Issu ed In fu rth eran ce o f C oo perative E xtens ion W ork. acta of M I IY B an d Ju ne 30 . 1 91 4. IIIAmCnded. Kansas S ta te U nlten ity C ou nty Ezt en s io n C oun ci ls . and U nite d S tate s D e pa rtm eD t o f A sr ic uJ tu re Cooperating. John O . Dunbar. D i r ec to r. A l l e du c at io ll ll l programs andJDateriaJs a va il ab le w it ho ut d Is c: ri ml na tI on o n the basis o f r ac e. c ol or . n at io na l o z ! a I a . l C S . or baadicap. 2 7 9-J M ; 8-79 -5 MFile Code: 4H and Youth 2

incubating eggs

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