This is a brief list of other incubation and embryology experiments that can be done in the classroom. Many other types of projects related to incubation could be conducted. Let imagination be the guidelines.
In project 1 through 9, the developing eggs could be candled at regular intervals (perhaps every 2 days), and those that show no signs of development or blood rings removed, broken open and examined. Abnormalities should be noted and recorded. Candling of eggs that are not being turned (projects 3 and 4) should be done gently and with as little rotation of each egg as possible.
When the effect of temperatures on rate of development is being studied, daily sacrifice of living embryos and examination of them is very educational. These embryos could then be preserved. The number of eggs necessary for this may present a problem. At hatching, the incidence of malformed, crippled or late-hatching chicks should be recorded as well as the total time required completing development. Specimens with abnormalities could be preserved.
Remember that experimental groups should contain sufficient numbers to insure meaningful results. Replication of experimental treatments is desirable. The number of eggs in any treatment group should be based on the expectation that probably 20% or more will be lost through infertility and normal embryo mortality.
Effect of age of eggs at setting on hatchability. Incubate eggs that are 3 weeks old or older when they are placed in the incubator and eggs that are 1 week old or less. Compare the differences in hatchability and differences in time required for hatching.
Effect of improper temperatures during the holding period on hatchability. Place groups of eggs in a household refrigerator for several different lengths of time, such as 24, 48 and 96 hours. Keep control eggs under ideal (55-58°F) conditions. Similarly, some eggs could be held at room temperature or preferably above 80°F. All eggs should be the same age and from the same source. Incubate them and compare the results.
Effect of turning eggs during incubation on hatchability. Place two groups of eggs that are the same age and from the same source in the incubator. Distinguish between the eggs in each group by using an identifying mark on the eggs in one group and a different mark on the eggs in the other group. Turn the eggs in one group three times a day for the first 18 days of incubation. Do not turn the eggs at all in the other group. Compare the hatchability.
Effect of turning eggs on embryo development and hatchability. Compare a group of eggs turned on any regular schedule (three times per day, five times per day, etc.) with eggs that are not turned at all and/or eggs turned three times a day every third day or per selected intervals. Compare the development and hatchability of the embryos.
Effect of egg position on hatchability. Incubate one-half of a setting of eggs with the small end of the eggs higher than the large end of the other one-half of the eggs. Turn both groups of egg regularly, but maintain the same end positions respectively on each group of eggs throughout the incubation period. Compare hatchability and embryo development.
Effect of egg size on weight of the chick. Set eggs of significantly different sizes and compare the weight of the baby chicks at a given interval of time after hatching.
Effect of shell porosity on hatchability. Set one group of normal eggs and another group that has had the shell pores sealed by dipping the eggs in mineral oil. Compare the hatchability and embryo development of the two groups.
Effect of incubation temperature on hatchability and embryo development. If two incubators are available set eggs in one and operate it at recommended temperature and humidity levels. Place eggs in the other and operate it at a marginal level of temperature, such as 97°F or 103°F, throughout the incubation period. Recognizing that it is not as sound experimentally, one incubator could suffice. First, incubate a group of eggs at a marginal temperature level for the incubation period and record the results; then incubate a group of eggs under recommended procedures and compare the results of the two groups. A variation would be to fluctuate the temperature every day or every few days on a group of eggs throughout the incubation period say, from 97°F to 103°F.
Effect on relative humidity on hatchability. The same general type of plan as outlined in Number 8 could be followed except that the humidity would be varied while all other procedures were kept normal.
Preserving chick embryos. Embryos can be harvested and preserved in a 10% solution of formolin (1 part 37% formaldehyde and 9 parts water). A small glass jar with a screw cap works well for this purpose. Refer to Animal Micrology by Michael F. Guyer for more information