Artificial Incubation

As my favorite time of year rolls around, springtime brings an abundance of fresh fertile eggs to be collected.  Our hens are laying like mad and the incubator is primed and ready to go.  At maximum capacity our incubator holds around 250 standard sized chicken eggs.  Our hens lay anywhere from a medium to a large sized egg.   Different breeds produce different size and color ranging from white, tan, brown, to even green, pink and blue. 

There are 5 levels to our incubator.  In the top area is where the humidity pan and hydrometer is located along with the motor and whatnot that makes the incubator function.  Then there are 3 levels of turning racks for egg trays.  The racks turn the eggs automatically every so often and can also be turned manually depending on what position the switch is in.  The lower level is where the hatching tray is placed.  This is where the eggs are moved to during the last three days of incubation, where they require a slight raise in humidity and no longer need to be turned.  We have the hatching tray separated into 3 different sections to keep different breeds from getting mixed up as the chicks hatch.  The temperature can be monitored from the outside of the incubator as the bulb of the thermometer is placed through a hole in the side of the incubator. 

For best hatch results eggs should not be stored longer than 2 weeks prior to incubation.  We set eggs every week during breeding season to maximize our hatch results.  The longer you store eggs past 2 weeks the lower your hatch rate will be.  We store our eggs at room temperature (our house stays around 69-71 degrees Fahrenheit) and they should be turned daily.  We elevate one end of the container or egg tray on a solid object and alternate ends every day.  You can use any solid object to elevate your egg trays as long as it's stable and won't fall.  Eggs should be stored and set in incubator large end up (air cell up).  In smaller incubators that require manual turning it is okay to set eggs on their sides as long as your mark one side X and the other side O so you can ensure all eggs are turned properly.  During the first 18 days of incubation eggs should be turned ideally four to six times a day, but two or three times will do.  Our automatic turning racks turn the eggs every four hours (six times in a 24 hour period.) 

It is important to maintain proper humidity and temperature during incubation for a successful hatch.  Our incubator maintains a constant 100 degrees Fahrenheit thanks to an automatic setting by the manufacturer.  It can be adjusted but we haven't ever found it necessary.  Humidity pads can be added or removed to adjust humidity.  I try to keep the humidity around 60% during the first 18 days of incubation, and up around 65-70% the last 3 days.  Anything lower than that will cause the hatch to be too dry and the chicks will become stuck inside the egg.  The eggs can be lightly sprayed with water each day the last 3 days of incubation to raise humidity.  Use a clean spray bottle with warm water.  It is important that you open the incubator as little as possible to maintain the proper temperature and humidity inside.  Maintaining good humidity during incubation is crucial because as the chick develops, moisture evaporates from the egg.  If too much is lost (humidity too low) the chick will become dry and stuck, if too little is lost (humidity too high) the chick will be too soggy and may drown.  In terms of mortality however, I have found that chick deaths are more often the result of a humidity that is too low than a humidity that is too high.  We have had successful hatches with little to no drowning when the humidity was kept at 65-70% the entire incubation.  In situations of a dry hatch, the chicks become stuck to the membrane of the egg and die of exhaustion if not assisted by manually opening the shell.

Under normal circumstances when humidity and temperature were maintained properly, we have found that sometimes a chick or two will begin to hatch and not progress past the pipping stage regardless of ideal incubator conditions.  This is natural selection taking its course and usually means that the chick had a defect or is not in the best of health.  If assisted to hatch the chicks are found to be usually unable to walk or stand due to abnormalities or deformities in the legs, neck, head, or vertebra.  In most cases these chicks have to be culled because they are unable to eat or drink normally. 

If you do assist a chick to hatch, whether it has dried up and stuck to the membrane or whatever, make sure the membrane is no longer vascular first.  When a chick is ready to hatch the blood in the vessels around the chick in the membrane will dry up.  If you tear through the membrane before the blood has dried up, the chick could die of blood loss or develop an infection.  If you see blood vessels or notice any bleeding, put the egg back in the incubator and try again in a few hours.  Peel around the shell in a line imitating as best you can how a chick hatches naturally.  Once you get almost all the way around the egg, try to let the chick kick its own way out.  If it is too weak, you can remove the top cap and allow the chick to come the rest of the way out.  

During the last 3 days of incubation the incubator needs to be disturbed very little, only checking it once a day to fill the humidity pan, spray the eggs, and (if any) remove any newly hatched chicks.  We leave the eggs in the hatching tray an additional day or so as some chicks can hatch later than 21 days depending on genetics and a number of factors.  After that however, any eggs remaining are discarded.