27/03/2020
Incubating Chicken Eggs
I am still amazed every time I witness a little wet chick that resembles a prehistoric creature emerge from an egg shell. In three short weeks, baby chicks hatch unassisted, pop up and become an active fluff ball within a few hours. Elementary schools everywhere are participating in hatching projects to provide incredible educational experiences for their students. Chicken eggs are merely a huge embryo that we can clearly see without a microscope, providing amazing educational opportunities. My first hatch was an adventure for my 9 year old son who signed up for a 4-H poultry project. I remember thinking, “I am an embryologist for cows; how difficult could this be?” Well, sometimes it is difficult, but most often, the experience provides an unexplainable joy with a relatively small investment of time and money.
Temperature: The easiest part of hatching chickens is purchasing an incubator and keeping the temperature at 99.6◦F. Most incubators regulate the temperature automatically. Use a thermometer to confirm the temperature and to monitor on a daily basis. Incubating at even one degree too hot or too cool can decrease your hatch rate. Most incubators lose the ability to maintain the correct temperature over time. Perhaps the forced air fan system fails or the rheostat stops working. For whatever the reason, do not expect an inexpensive incubator to last forever; monitor the temperature in order to quickly take emergency steps to remedy any problems.
Humidity: A hygrometer is an instrument used to measure the amount of humidity in the air. The ideal humidity range for incubating chicken eggs typically falls between 35 and 45%. This range is meant to mimic the underside of a hen. Getting the humidity in your incubator into the optimal range may be easy - momentarily; staying consistently in the optional range may be difficult.
Our first incubator was a Styrofoam box with an intricate system of water wells in the bottom compartment that we picked up from a farm store. Typically the directions have you filling up one or more reservoirs inside the incubation chamber which in turn will have fans blowing air across the surface of the water. The air circulation increases the humidity through evaporation. Typically, a thermometer is provided, but not a hygrometer to measure the humidity. Even though the actual humidity of the incubation chamber is not measured, great success can still be achieved by simply following the manufacturer’s directions. The room temperature and humidity where your incubator sits plays a big role in how much effort it will take to reach and maintain moisture levels that satisfy a developing chick embryo. A drier area may require more frequent filling.
When the room humidity is drier, say 20 to 30%, the water level needs to be monitored more closely and sometimes filled twice daily to keep the humidity above 35%. It is okay for the humidity in the incubator to drop occasionally, as long as the average, overall humidity stays between 35 and 45%.
Indoor humidity can vary greatly depending on the season of the year and whether the air conditioner or heater are running; cooling and heating have a substantial negative effect by lowering the humidity in the air. Indoor incubation during the winter is a challenge when humidity falls, especially if it drops to less than 25%.Conversely, in the summer, the garage is my favorite place to incubate with the high outdoor humidity providing a quite favorable hatch without having to fuss with the water as much.
The manufacturer’s directions will typically call for a slight increase in humidity the day before the chicks are due to hatch. Caution, do not decrease ventilation in order to increase humidity. The oxygen needs for the hatching chick are compromised by lowering ventilation on hatch day. If any ventilation changes are made surrounding the hatch, it should be to increase ventilation, while using alternate methods such as filling an additional water chamber or adding a sponge or a wick to increase the surface area for evaporation.
The Hatching Process: The chick begins to hatch by “pipping.” The chick instinctively creates the initial small hole in the egg that becomes an artistic circular cut at end of the egg with the widest diameter. All of the chicks pip out of the same fat side of the egg where the air cell resides. The pipping process creates a distinct disc shaped port hole reminiscent of a submarine hatch. Once the hatch is opened, the chick uses its legs to push the larger portion of the shell off of their body.
The newly hatched chicks offer a temporary boost in the overall humidity in the incubator as well. Every effort should be made to not open the incubator lid once the first chick has pipped or hatched to preserve the delicate humidity levels. Any other chicks that have pipped are subject to quickly drying and subsequent tightening of their surrounding membranes. This can lead to a slower, incomplete hatching or even suffocation. The initial “pip” may be difficult to see; once the egg’s armor has been pierced, drying can occur within minutes. Utilizing a way to add water without opening the lid during the hatch can prevent a sudden drop in humidity; running a tube through a small hole will facilitate safely adding water. I understand the desire to move a newly fluffed chick immediately out of the incubator to gain access to food and water, but you must resist all temptations. Luckily, the first hatched chick and each chick to follow has just absorbed their yolk sac. The yolk sac is used as a source of food and hydration for up to 3 days. Granted, you will not need to wait three days, as the hatch is typically completed in less than 24 hours. Waiting will increase the survivability of the clutch. All of the hatchlings can be moved into a brooder at the same time.
Do’s and Don’ts:
- Place your incubator in an area with a consistent room temperature and humidity.
- Keep the temperature as close to 99.6◦F as possible.
- Candle the eggs for fertility at day 7 or greater; discard any unfertile eggs.
- Keep the eggs rotated three times per day for the first 14 days.
- Keep the water level at 75% or greater at all times.
- Do not let the incubator dry out.
- Do not decrease ventilation as a means to increase humidity.
- Don’t be afraid to add water twice daily until the first chick pips.
- Do not open the your incubator while chicks are in the pipping/hatching phase.
- Chicks can warm/fluff in the incubator for 24 hours if you do not have hatcher.
- Add a wick or a sponge to increase the surface area for evaporation to increase moisture levels in the incubator as needed.
Happy hatching!
About the Author
Dr. Colleen Lewis is a 1996 graduate of Kansas State University, College of Veterinary Medicine. Her career has taken her to many places as a practice owner, consultant, embryologist, and mentor. She enjoys mixed animal practice, teaching, traveling, farming and high school sports with her husband, Andrew and their three boys.
