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Variation of Chicken Embryo Development by Temperature Influence
Anna Morgan Miller
Rockdale Magnet School for Science and Technology
Anna Morgan Miller
Rockdale Magnet School
1174 Bulldog Circle
Conyers, GA 30012
January 2012
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Table of Contents
Abstract…………………………………………………………………………………………..3
Introduction………………………………………………………………………………………4
Literature
Review……………………………...……………………………………….……………………6
Research
Methodology…………………….……………………………….……………………………….8
Data Analysis……………………………………………………………………………….……9
Results……………………………………………………………………………………………14
Conclusions………………….…………………………………………..………………………15
Literature
Cited……………………………………………………………………………………………..16
Appendix
A…………………………………………………………………………………………………17
Appendix
B…………………………………………………………………………………………………18
Appendix
C………………………………………………………………………………………………….19
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Abstract
The purpose of this project was to investigate the effect incubator temperature has on chicken
embryo development. The research hypothesis stated that incremental temperatures will affect
the gender of the chick, the mass of the eggs will increase with each degree increase, the body
mass of the chicks after hatching will be greater with each degree increment increase, and the
most chicks will hatch at 37.7 degrees Celsius. Procedures consisted of incubating 6 trials of 6
eggs, weighing each egg every 2 days on a scale. After the chicks hatched, gender was
determined by looking up the vent of the chick. Then they were weighed on a scale and ten
placed in a brooder. Data was analyzed using ANOVA and Minitab14 to determine if the data
was significant. It was determined that for temperature 37.7 degrees Celsius, the most chicks
were hatched. One my null hypotheses were supported, because the chicks and the eggs
continued to decrease throughout every trial. There were more female chickens than male that
hatched, but there is not enough gender data to determine whether temperature affecting the
gender is statistically significant.
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Introduction
The incubation of fertile chicken eggs is a precise process. The incubator temperature
must stay constant all twenty-one days of the incubation period. Incubator temperatures for
chicken eggs can range from thirty-six to thirty nine degrees Celsius, but no studies show which
temperature is best for the development and health of the chicken embryos (Lourens, 2011).
The research project will determine which of the six degree temperatures39.4oC, 38.8oC,
38.3oC, 37.7oC, 37.2oC, and 36.6oC, is best for the development of chicken embryos. These
temperatures are the recommended incubating temperatures for the development of chickens.
The research problem is, the effect of temperature on chicken embryo development. The
purchased incubator can hold seven eggs at a time, but each temperature increment will have six
trials. The total number of chicken eggs being used for this research project is thirty-six.
A research and null hypothesis must be established for this project. There are 4 research
hypotheses, but the main hypothesis is, as temperature increases, the mass of the chicken
embryos will increase. The null hypothesis is, incremented temperatures of an incubator do not
affect the mass or gender of the embryos.
The independent variable in the research is temperature, and the dependent variables are
chicken embryo development, gender of the chicks, mass of the eggs at the day point, and mass
of the chicks after hatching. By changing the independent variable, the proposed effect to the
dependent variable would be an increase in embryo’s body mass. Every two days of the
experiment, a candling observation will be held. This will assist in the observations of the
embryo development, and the determination of which temperature results in the best and
healthiest embryo development.
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The limitations to the project are temperature. The incubator has to be located in an
environment with a constant temperature; otherwise, the data could be skewed. Too much
sunlight or heat from a source other than the incubator could affect the development of the
embryos. This would be a bias in my research and would not provide accurate results.
Determining which recommended temperature increment is the best for embryo
development will help in the production of chickens. Healthier chickens can be produced when
they are incubated and taken care of in the best conditions. These conditions are temperature,
location, and type of incubator. Previous experimentations have proven that not controlling
eggshell and incubator temperature can result in chick quality and hatchability problems
(Lourens, Meijerhof, Kemp, & van den Brand, 2011). This experimentation for this project will
begin in August.
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Literature Review
When incubating eggs, maintaining a steady eggshell and incubator temperature in
necessary to produce healthy chicks. Not controlling eggshell and incubator temperature can
result in chick quality and hatchability problems (Lourens, Meijerhof, Kemp, & van den Brand,
2011). These problems include the embryos sticking to the eggshells during incubation, or
having crooked legs when they hatch (Hamre, 2011). This is bad because it can increase the
mortality rate of the developing embryos. The embryos can also die if they are placed close to
windows. The sun and outdoor temperatures can increase or decrease the temperature of the
incubator depending on the season and time of year.(Hamre, 2011).
Temperature, the independent variable, can be defined as the warmness or coldness of an
object. Warmer temperature objects release their heat to cooler temperature objects until the two
objects are equal in temperature, also known as thermal equilibrium (Lynds, 1995). When
incubating chicken embryos, the incubator temperature should remain between 36-39 degrees
Celsius (MSU, 2010. Hamre, 2011).
Chicken embryo development, a dependent variable, relies on the temperature of the
incubator (Lourens, Meijerhof, Kemp, & van den Brand, 2011). If temperature is a degree to
high or low from the recommended temperatures, the embryos will die (Clauer, 2009).
Recommended chicken incubation temperatures are 36-39 degrees Celsius. Different factors
can affect the chicken embryo development, such as temperature, lighting, and location of the
incubator (Susan, 2007). Another dependent variable is body mass of the chicks after hatching.
The body mass of the chick is the comparison of the chicks’ height to its weight (MedTerms,
2011). Light, such as the sun, could increase temperatures of the incubator, and being placed
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next to something cool like air conditioners could decrease incubator temperature (Tarvin &
Chester, 1997). The location of the incubator has the same effects as the lighting. Incubators
placed in warm places will increase in temperature, and incubators placed in cool places will
decrease in temperature. The room temperature surrounding the incubator should be between
18-26 degrees Celsius (Goffle). This will ensure the quality and life of the eggs. The gender of
the chicks is another dependent variable in the research experimentation. It will be determined
by a process called chicken-sexing (Bramwell, 2003).
A previous study was conducted to find that if the temperature of an incubator is not
controlled very well, there will be hatching and developmental problems (Lourens, 2011).
Developmental problems are bad because the chickens could be born with crooked legs, or brain
development issues. Even fatality can occur. If there is temperature variation in the embryos it
is a result of variation in the incubator temperature. Years ago, a study was conducted to
determine how the chicken embryo developed with different pre-incubation temperatures. This
experiment tested the effects of different time spans of pre-incubated chicken embryos at
different temperatures (Arora & Kosin, 1968).
This research project somewhat relates to the previous experiments. It will test the effect
of temperature on chicken embryo development. The research project is, “Variation of chicken
embryo development by temperature influence.” This research is important because there is not
a definite incubator temperature that has been proven to be the best for chicken embryo
development. By observing which temperature results in healthier growth development of the
embryos, healthier and better chickens can be produced.
8
Methodology
The IV is temperature. The temperature levels are 39.4, 38.8, 38.8, 37.7, 37.2, and 36.6
degrees Celsius. The DVs of the research project are chicken embryo development, body mass
(g), gender, and mass of eggs at day points. The embryo development will be determined by
taking pictures of the candling observations and comparing each trial’s procedures. Body mass
and gender will be determined after hatching. Eggs will be massed every 2 days along with the
candling operations.
The research procedures start with getting an incubator with temperature control, and 36
fertile chicken eggs. Each IV level will be preset 24 hours before incubation begins, and so that
the accurate temperature can adjust. The eggs will be incubated for 21 days per trial, and will be
massed and candled every 2 days. After hatching, body mass and gender will be recording, and
the chicks will be placed in a brooder. This brooder will keep them warm until they grow
enough feathers to stay warm by themselves.
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Data Analysis
The first 2 trials of testing temperature variation on chicken embryo development and
gender did not support the researcher’s hypothesis (DF= 1; F= 14.32; P=0.000). The null
hypothesis was supported because only 1 out of 10 eggs hatched, thus the researcher could not
support the hypothesis that temperature will affect a chicken’s gender and weight. During
candling observations, the eggs looked like they were developing correctly, but really they just
liquefied and eventually began to rot. Only one egg hatched. The chick was black and yellow,
but the gender was not determined [See Figure 1].
Figure 1
Figure 1: “Hershel the Chocolate Chicken,” is a healthy, black and yellow mixed breed chick.
The average weight of the eggs for both trials gradually decreased throughout the
experiment. This is thought to be a result of the embryo taking in the nutrients of the yolk in the
egg (the chick the hatched was from trial 2, 37.2 degrees Celsius). The percent difference in the
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weight of the eggs from each trial was conducted using Microsoft excel and Minitab14 [See
Figure 2 and Figure 3].
A second round of experimentation is being conducted and trials 3 and 4 are following
the same pattern as trials 1 and 2: the weight of the eggs is decreasing throughout the incubation
process. The same thing has happened with trials 5 and 6.
The second trials 3 and 4 and third trials 5 and 6 also did not support the researcher’s
hypotheses of temperature affecting gender of a chick and temperature affecting the weight of
the chicken after hatching (DF= 1; F= 14.32; P=0.000). The researcher did not have enough
chickens to hatch to prove whether those hypotheses were significant or not. The eggs were only
candled once a week during the third and fourth trails. This resulted in 3 eggs hatching instead
of 1. No candling observations were conducted during the fifth and sixth trials of incubation,
and 6 chickens hatched. Although candled procedures were not one of the hypotheses, it seemed
to have an effect on the amount of chicks that hatched. This could be further tested and observed
in a project continuation.
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Figure 2
Figure 2: As the time of incubation increases, the percent difference in weight change of the eggs also increases.
Figure 3
Figure 3: As the time of incubation increases, the percent difference in weight change of the eggs also increases. Egg 3 is
an outlier: There was a great weight variance from day 13 to day 18.
0
2
4
6
8
10
12
14
Day 5 Day 7 Day 9 Day 11 Day 13 Day 15 Day 18 Day 20
Egg 1
Egg 2
Egg 3
Egg 4
Egg 5
Egg 6
-10
-5
0
5
10
15
Day 5 Day 7 Day 9 Day 11 Day 13 Day 15 Day 18 Day 20
Egg 1
Egg 2
Egg 3
Egg 4
Egg 5
Egg 6
Comparison of Egg Mass from Day 5 to Day 20
(37.2 Degrees Celsius) %
Ch
ange
in M
ass
(g)
Comparison of Egg Mass from Day 5 to Day 20
(36.6 Degrees Celsius)
% C
han
ge in
Mas
s (g
)
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Figure 4: As the time of incubation increases, the percent difference in weight change of the eggs also increases. Egg 7
was dropped while being weighed, and therefore died.
Figure 5: As the time of incubation increases, the percent difference in weight change of the eggs also increases.
0
2
4
6
8
10
12
14
16
Day 3 Day 6 Day 8 Day 10 Day 13 Day 15 Day 17 Day 20
Egg 1
Egg 2
Egg 3
Egg 4
Egg 5
Egg 6
Egg 7
0
2
4
6
8
10
12
14
16
18
20
Day 3 Day 6 Day 8 Day 10 Day 13 Day 15 Day 17 Day 20
Egg 1
Egg 2
Egg 3
Egg 4
Egg 5
Egg 6
Egg 7
Comparison of Egg Mass from Day 3 to Day 20
(37.7 Degrees Celsius) %
Ch
ange
in M
ass
(g)
Comparison of Egg Mass from Day 3 to Day 20
(38.3 Degrees Celsius)
% C
han
ge in
Mas
s (g
)
Figure 4
Figure 5
13
Figure 6: As the time of incubation increases, the percent difference in weight change of the eggs also increases.
Figure 7: As the time of incubation increases, the percent difference in weight change of the eggs also increases.
0
5
10
15
20
25
Day 3 Day 5 Day 7 Day 9 Day 11 Day 13 Day 15 Day 18
Egg 1
Egg 2
Egg 3
Egg 4
Egg 5
Egg 6
0
2
4
6
8
10
12
14
16
Day 3 Day 5 Day 7 Day 9 Day 11 Day 13 Day 15 Day 18
Egg 1
Egg 2
Egg 3
Egg 4
Egg 5
Egg 6
Comparison of Egg Mass from Day 3 to Day 20
(38.8 Degrees Celsius)
Comparison of Egg Mass from Day 3 to Day 18
(39.4 Degrees Celsius)
% C
han
ge in
Mas
s (g
) %
Ch
ange
in M
ass
(g)
Figure 6
Figure 7
14
Results
After analyzing data with Minitab14 and ANOVA, it was determined that the data was
significant for the mass difference of eggs between the different temperatures. The null
hypothesis of temperature affecting gender was supported because only 10 out of 36 eggs
hatched, thus the researcher did not have enough data to support the hypothesis that temperature
will affect a chicken’s gender and weight.
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Conclusions
Incubation temperature does affect the mass of a chicken egg, but it causes the weight to
decrease, not increase. Although there were more female chickens than male chickens that
hatched, there is not enough data to determine if the temperature of the incubators affecting the
gender was significant. Some bias in experiment that could have prohibited the rest of the eggs
from hatching includes too much humidity in the incubators, causing the embryos to drown, or
not enough rotation each day, causing the embryo to stick to the shell and die.
16
Literature Cited
Arora, L. (1968). the response of the early chicken embryo to preincubation temperature as evidenced
from its grossed morphology and mitotic pattern. Retrieved March 30, 2011, from JSTOR:
Physiological Zoology : http://www.jstor.org/pss/30158488
Bosk, B. (1974, June). How to sex day-old chicks. Retrieved April 15, 2011, from Mother Earth News:
http://www.motherearthnews.com/Sustainable-Farming/1974-05-01/How-to-Sex-Day-Old-
Chicks.aspx?page=3
Bramwell, K. (2003). Sexing chicks in the backyard flock. Retrieved March 29, 2011, from The poultry
site: http://www.thepoultrysite.com/articles/95/sexing-chicks-in-the-backyard-flock
Clauer, P. (2009). Incubating Eggs. Retrieved March 29, 2011, from Virginia Cooperative Extention:
http://pubs.ext.vt.edu/2902/2902-1090/2902-1090.pdf
Definiton of Body Mass Index. (2011). Retrieved March 29, 2011, from MedTerms:
http://www.medterms.com/script/main/art.asp?articlekey=16125
Hamre. (2011). Hatching and Brooding small numbers of chicks. Retrieved March 23, 2011, from My pet
chicken: http://www.extension.umn.edu/distribution/livestocksystems/di0631.html
Hatching Chickens. (2010). Retrieved May 3, 2011, from Fantastic Farms: http://www.small-farm-
permaculture-and-sustainable-living.com/hatching_chickens.html
Incubation of eggs. (n.d.). Retrieved March 29, 2011, from Goffle Poultry:
http://www.gofflepoultry.com/index.html
Lourens, A. (2011). Energy partitoning during incubation and consequences for embryo temperature.
Retrieved February 14, 2011, from http://library.wur.nl/desktop/
Lynds, B. (1995). About Temperature. Retrieved March 28, 2011, from
http://eo.ucar.edu/skymath/tmp2.html#Tmp
MSU. (2010, October 14). Poultry: Reproduction and Incubation. Retrieved March 28, 2011, from
MSUcares: http://msucares.com/poultry/reproductions/poultry_temp.html
Rock, J. (2010, May 19). How to tell if a baby chick is a male or female. Retrieved April 15, 2011, from
eHow: http://www.ehow.com/how_6529883_tell-baby-chick-male-female.html
Tarvin. (1997). Modeling incubation temperature: the effects of incubator design, embryonic
development, and egg size . Retrieved March 29, 2011, from Poultry Science:
http://ps.fass.org/cgi/content/abstract/76/1/124
What is Biology? (2010). Retrieved March 30, 2011, from Kwantlen Polytenhnic University:
http://www.kwantlen.ca/science/biology/what_is_biology.html
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Appendix A
Hypothesis A- Incremental temperature changes will affect the gender of the chick.
Sub-Hypothesis B- The mass of the eggs will increase with each incremental temperature
increase.
Sub-Hypothesis C- The body mass of the chicks after hatching will be greater when degree
increments increase.
Sub-Hypothesis D- Chicks will be healthiest (determined after hatching) when incubated at
37.7OC.
Experimental Design Diagram
IV:
Temperature
Group 39.4 38.8 38.2 37.7 37.2 36.6
# of Trials 6 6 6 6 6 6
DV: chicken embryo development, body mass (g), gender, mass of eggs at day point
Constants: location, type of incubators
18
Appendix B
Materials-
- 36 fertile chicken eggs
- Brooder
- Candler
- 2 incubators
- Scale
- Gloves
- Heat Lamps
Budget: $100.00
Projected Total: $457.55
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Appendix C
Order 36 fertile chicken eggs, 6 for each of the 6 trials.
Obtain a forced-air incubator with temperature control.
Place the incubator in a stable indoor environment with little temperature fluctuation.
Fill the water trough ¾ full of warm water to ensure humidity.
Pre-heat the incubator to the first IV temperature, 39.4 degrees Celsius, and leave for 24
hours to ensure a stable temperature.
Build a Candler. Acquire a cardboard box and a light bulb. Cut a hole in the box just big
enough for the egg to fit in. Place the light bulb directly under the hole and turn on when
eggs are ready to candle.
Take 6 of the 36 embryos to candle and mass them.
After the mass and candling, place them in the incubator for 21 days.
Every 2 days of incubation, observe the developing embryos with a mass and candling
observation.
Record data by taking pictures and writing data in the log book.
During incubation, be sure to keep the water trough filled to help the embryos develop.
After 18 days of incubation, fill the water trough completely full of warm water. This
will increase humidity to help the process of hatching.
Also after the 18th day of incubation, place kitchen paper in the bottom of the incubator.
This will give the chicks a better foot grip after hatching when they are learning to walk.
After hatching, mass the chicks.
Determine the gender of the chicks. First, wash your hand so that the chick does not get
an infection from the dirt that collects on your hands. Put on gloves. Hold the chick’s
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neck gently in between your forefinger and middle finger. Turn the chick upside down to
find the vent. The vent is located under the tail. Gently squeeze the chick’s rear so that
the vent will be easier to see. If a flesh-colored bubble is visible, it is a male. If there is a
no bubble, then it is a female.
After sexing and massing, place the chicks in a brooder. Keep a constant supply of food
and water in the brooder, and kitchen paper on the floor of the brooder.
Repeat all of these steps for each IV temperature. Keep incubator location constant.
