Adventures In Caretaking: Solving the Mystery of Chicken Egg Incubation

After the first few attempts at incubating chicken eggs resulted in less than stellar hatches due to humidity issues, I spent countless hours and sleepless nights researching on the internet and settled on the following modified version of the "dry method", which has produced two consecutive 90% hatches! There is a lot of conflicting information out there regarding the ideal humidity for incubation and I credit Buddy Henry of Backwoods Poultry Farm for setting me on the path to success.

Below is a step-by-step tutorial of this technique.

Days 1-17: Maintain relative humidity (RH) at 35-40%, allowing it to drop to 25% before adding water and boosting it back up to 35-40%. All vent plugs are removed during this period to maximize air flow and facilitate evaporation. The eggs also need to be turned at this stage...more on that below.

Days 18-21: Maintain RH at 55-60%. 58% is most ideal. I've found that I need to plug the top front vent in order to maintain a stable humidity at this stage. The RH will rise as the peeps hatch. This is of no consequence and no action needs to be taken. During this stage, the hatch phase, the eggs are no longer turned.

Humidity is a very important aspect of incubation. If the humidity is kept too high, the air sac cannot grow large enough and the peep will drown in fluid when it pips through the membrane, prior to pipping the shell. Too low, the peep will be shrink-wrapped inside the membrane and will simply struggle until it dies. During days 1-17, too low is better than too high. My problem was that I was keeping it too low during the hatch and my peeps were being shrink-wrapped.

As the peep develops, the egg needs to lose approximately 12-14% of its weight through evaporation. Humidity is the tool by which you accomplish this goal, so it's important to keep an accurate watch and keep track of your humidity and egg weight so you can adjust your techniques as needed for subsequent hatches.

This is the incubator I'm using. It's an old Hova-Bator from GQF Mfg.

Here are the eggs from Groups 7 & 8, numbered and ready to go into the 'bator...

The brown eggs are a Rhode Island Red/Barred Rock cross and they are fresh off a farm in Santa Rosa. The white eggs are from Trader Joe's and they are seven days old at this point.

Next, each egg is weighed on a gram scale and the weights are recorded and averaged.

Day 1 average Santa Rosa egg weight: 58.3 grams
Day 1 average Trader Joe's egg weight: 59.8 grams

Finally, the eggs are placed into the turning rack, pointy end down...

If you don't have an auto-turner, you can either lay them on their sides and turn them by hand or leave them in a carton with a block under one side and switch that to the other side a few times a day. If turning by hand, turn them an odd number of times each day (3-5) so they don't spend consecutive nights on the same side.

On day 10, I candle all the eggs and weigh them again. You can candle them at Day 7, but I often work with dark eggs so I wait until Day 10 to make it easier. This is what you want to see...

If the egg is clear with no veining, it's not viable.

Day 10 average Santa Rosa egg weight: 55.7 g. (-4.4%)
Day 10 average Trader Joe's egg weight: 56.6 g. (-5.4%) They have thinner shells.

At this point, I have 10 of 12 Santa Rosa eggs developing and 9 of 12 Trader Joe's. Only viable eggs are calculated into the average weights, so I've gone back to my Day 1 weights and removed the duds from the average.

Day 18...time to prepare for the hatch! The eggs are weighed, candled and removed from the auto-turner and the humidity is increased to 58%. I'm using the carton hatch method for the first time here rather than have eggs rolling all over the incubator floor. I'm now sold on this method. The water dishes with sponges help to increase and stabilize the humidity. In this climate, the water troughs which are built into the bottom of the incubator are not sufficient.

Day 18 average Santa Rosa egg weight: 52.7 g (-9.6%)
Day 18 average Trader Joe's egg weight: 53 g (-11.4%)

I've missed my target weight loss of 12% by a bit.

Now, the number one rule of hatching is DON'T OPEN THE 'BATOR! No matter what happens, no matter what justification you dream up, DON'T OPEN THE 'BATOR! If you open the 'bator while an egg is pipped, the membrane is going to instantly shrink-wrap that peep. You cannot open and close it fast enough to avoid this. You cannot overcome this by pouring hot water into the dishes, nor by misting the eggs with water. Simply DO NOT OPEN THE 'BATOR unless you're absolutely certain that there are no pips.

Here we go...they started pipping on Day 20 and the hatch went into Day 22...

Final result: 9 of 10 Santa Rosa peeps and 5 of 9 Trader Joe's (one of which soon died).

I'm claiming a 90% hatch rate on this because I'm not counting the Trader Joe's eggs, they were somewhat of a fluke.

Here are some of the peeps...

The Trader Joe's peeps turned out to be White Leghorns and the roosters quickly become very obvious...

Want to see it again? Here's Group 9; 36 Cuckoo Marans eggs from Crazy Flower Wines.

Day 1...

Day 18...

These eggs had lost an average of 11.4% of their weight at Day 18. Six of them were duds, but I left them in because they weren't stinky and because Marans eggs are difficult to candle.

Day 21...