Procedures:

I began this experiment by researching chickens and obtained information on incubation and egg hatching. I found several listings for farms that sold fertilized eggs and made arrangements to pick up two sets of eggs; one fresh and the other from cold storage.

Prior to picking up the eggs I constructed the cardboard incubator and a candling unit which I set up in my basement where there would be no drafts.  I began monitoring and recording the temperature in the incubator and had to make several adjustments to achieve the correct constant temperature of 38.6˚ C (101.5˚ F).  As reflected in the Temperature Chart, the temperatures inside the box the first two days were deadly hot as they soared to 105˚ F (40.6˚ C).  This environment would have killed the embryos in a short period of time.  I changed the bulb from 100 watts to 75 watts and cut in another vent at the top to let more heat escape.  The next two days the temperature inside the box settled to the high range for safe incubation.  To solve this minor discrepancy I opened the vents about 75% of their maximum potential.  This adjustment achieved the constant desired temperature I sought.  It would be extremely difficult to regulate the temperature if the incubator was near a draft or sunny window.

I set up the candler on a table in the darkest room in the basement.  The darker the room the more transparent the egg becomes when placing it up to the candling unit.  Next to the candler I kept my digital camera, a ruler and paper to record my findings.

 View Exps220 Temperature Chart

 Care of Eggs:

The eggs came packed in cartons with the large ends of the eggs pointing up.  I immediately marked them fresh or refrigerated with an M, N, and E to organize the turning process.  The eggs must be turned three times daily and can be rotated toward and away from the bulb.  I then chose three eggs from each the fresh set, and the refrigerated set.  These would be my “test” eggs that I would weigh and measure on day 0, 5, 10, 15, and 20.  Upon examination of my weight chart, only three of the test eggs, two fresh and one refrigerated, survived.

Never wash eggs because the protective cuticle will be removed and it becomes susceptible to contamination.  Always pack the eggs with the large end up, and lay them on their sides with the large end slightly raised when incubating.  The large end is where the air sac is located.

Hands must be clean when handling the eggs in order to decrease the possibility of bacteria infections.  Before placing eggs in the incubator they should be labeled with pencil only.  I suggest using the single letter M for morning, N for noon, and E for evening.  This 3-way marking is necessary for the correct turning of the eggs because it allows the longest time period, overnight, to be rotated equally between the three sides.  If eggs are not turned properly then the embryos will stick to the sides and eventually die.

OBTAINING THE EGGS: (Manipulated variables)

 Purchasing “fertilized” eggs from a small farm, rather than from a hatchery, does not guarantee that 100% of the eggs will be fertile.  You can easily detect and remove unfertilized eggs during the candling process.

There are many places to obtain fertilized eggs including small farms found in Michigan’s U-Pick directory.  Wolcott Mill Metropark, a 250-acre working farm and Learning Center in Macomb County, gladly takes back any chicks that hatch.  The cost for fertilized eggs is $1.00 per dozen.  I received three dozen eggs, half of them fresh, and the other half hatched a week earlier and were held in cold storage.  Both sets of eggs came from the same brood of hens and both will be incubated under the same conditions.  The manipulated variables are refrigeration of the eggs and their age.

I separated the eggs with a cardboard partition cut into a strip.  I checked the temperature several times a day and noticed that if the atmosphere surrounding the incubator became cooler the temperature inside the box would start to drop.  In those instances, I placed a piece of aluminum foil over the top to reflect back the heat and light.  The embryos growth will slow down when their internal temperature reaches 90˚ F (32.2˚ C) but more significantly, the eggs will quickly overheat and expire if their internal temperature reaches 103˚ F (39.4˚ C). 

I turned the eggs three times each day  with thoroughly washed hands.  Germs from hands can invade the eggs through their pores and cause bacterial infections that take the shape of a blood ring.  However, I always washed my hands and many of my eggs developed bacterial rings anyway.  I learned that bacteria can begin to form at the nest due to environmental conditions and sanitation.

 I kept the water pan at the bottom of the box full at all times.  Humidity in the box is very important so that the embryos do not dry out.  Humidity can also be determined by the weight of the eggs.  If the egg is loosing weight too quickly, or has lost over 13% of its original weight, then more humidity is needed inside the box.  On the other hand, if you use too hot of water to fill the pan or if the humidity of the outside environment is too high, then chicks can become sticky and malformed.  Use tepid water to fill the pan when water level becomes low.