Neophyte and veteran incubators alike often ask, can I do X or Y just happened, are my eggs going to hatch? The internet is full of hatching musts and must nots, many of them contradictory, what is vital, what is important, and what is optional? As a newbie hatching eggs I asked those exact questions, and then went a step further and actually tried hatching eggs in certain situations to discover the answers. The following chart sums up that experience, the commentary to follow more fully explains each parameter:
Just a few caveats here, every attempt hatching eggs is different, even between hatching attempts by the same person, so please don’t take any of the following observations as hard and fast rules, especially as they all involve small sample sizes and often no control group. And while hatching eggs from any species is similar, what works for quail might not be right for guineas or whatever. This is also not verified, statistically significant data, it is merely observations of a private individual goofing around with an incubator. That being said, I have been trained in the scientific process and might even have a peer reviewed study published somewhere so there be a little method in my madness.
Materials and methods: unless otherwise noted, all eggs originated from our small breeding flock of coturnix quail (3 males, 13 females) which originated from a batch of shipped eggs we hatched last March. Our fertility runs at ninety percent or higher, embryonic death is ten percent or less, hatch rates are ninety percent or better on home raised eggs. We used a cheap Amazon incubator for the majority of these trials. Not all eggs were taken to hatch, cull eggs and dead eggs were opened and examined. Infertile eggs were eggs that showed no sign of development and are not counted in hatch rates or considered as part of any trial. Several external hygrometer/thermometer units were used during each hatch. Development means the eggs began to grow, even if they only made it to day 2. Hatch means a live chick that survives outside the shell. Early embryonic death is an embryo that died before or on day 8, late embryonic death is considered day 9 to hatch. Deformed means chicks or embryos with obvious anatomical defects. Coturnix quail hatch day 17 (range 15-20 days) in general.
So what is the most important factor with incubation? If you said incubation temperature, you’re right. Temperature is the one factor that will make or break your hatch. Too cold and eggs won't develop or will hatch late. Too hot and embryos die. I didn't mess with temperature very much, for obvious reasons, but I do have a psycho incubator that runs at 105F and did put a few eggs in there just to see what would happen. Eggs began to develop and died day 1-3 for fresh eggs. Day 3 embryonated eggs were also placed in the incubator for up to 12 hours without any obvious adverse effects (did not take to hatch, temp spikes can be associated with embryonic death and chick deformity), ie they didn't die suddenly but can't comment on longterm adverse effects. The most important aspect of your hatch is to have a several independent thermometer units in your incubator, go by those, not whatever the incubator tells you, adjust said incubator as needed.
After incubation temperature comes turning, as far as direct effect on hatch rates. Not turning your eggs won't destroy your hatch, but you can expect between a 25-50% reduction in hatch rates if you don't. So make sure those eggs get turned at least 3 times daily the first 12 days of incubation! Also move them around in the incubator so if there are cold or hot spots, it gets averaged out instead of exposing a few eggs to it all of incubation.
What about humidity? Strangely humidity didn't seem to effect hatch rates or development, even when eggs were exposed to either extreme (12% or 80%) all of incubation (lockdown was 70-80% for all eggs!). I had both huge and tiny air cells respectively but all the chicks hatched just fine, though anecdotally I thought the extreme dry hatch eggs hatched much more vigorous and lively chicks than the extreme wet hatch (or regular 45% hatches). Takeaway: don't worry too much about humidity, try and keep the average around recommended levels but don't panic if it spikes or tanks, unlike temp it will not destroy your hatch.
The other major factor affecting hatch rates was a pre-incubation factor. Storage temperature (fridge or room temp) and turning (or not turning) during storage made no difference to development or hatch rates. Age of the eggs made a huge difference! Eggs older than two weeks of age at the start of incubation had a 50% mortality rate by day 8, they all developed but then started dying off. You can incubate fridge eggs, just make sure they aren't a couple weeks old. You will get development but your hatch rate won't be great with older eggs.
In some camps, candling is thought to cause issues if done too much. I love the developmental part of incubation and pretty much candle every egg daily, the only issue I ran into was accidentally dropping eggs due to too much handling. So if you are accident prone, maybe minimize handling time, but otherwise, candle away!
Some of the other factors don't deal so much with the eggs themselves as the source, some of which you don't have any control over depending on your situation. I haven't done any experiments with genetics, hen nutrition, etc. and only have anecdotal observations on shipped eggs. There are also a few notes on very specific factors most normal hatchers aren't concerned about (water candling and trying an open egg hatch.) or issues that may arise infrequently during incubation.
Shipping eggs is notorious for causing issues with hatching, between temperature extremes, rough handling, and delayed incubation, a hatch rate of 50% is considered good in most cases. I can only comment anecdotally, on two shipments from different breeders totaling 3 dozen eggs, one was great and one was awful as far as length of time and damage to the package/eggs. In both batches I had a ten percent early embryonic death rate, ten percent late embryonic death rate (20% embryonic death compared to less than 10% on home raised eggs) as well as a ten percent deformed chick rate (0 on home raised eggs). But sometimes shipping is the only way to expand your genetics or even get certain birds (as in my case!), just know it comes with complications!
Genetics, hen nutrition, and fertility are all flock associated factors you may or may not have any control over, but good flock management is key to healthy and successful hatching, wherever you source your eggs!
Heat spikes: 3 day old embryos were exposed to 105F for 12 hours with no immediate effects, but I did not take them to hatch, high temps can be associated with embryonic death and deformity, so proceed with caution if this happens to your hatch, but it doesn't necessarily mean your hatch is doomed.
Freezing: as long as the shell doesn't crack, eggs exposed to cold temperatures preincubation haven't shown a difference in development or hatch rates (I've done both fridge eggs and eggs sitting out in our 32F garage for a couple days).
Warm ambient temperatures pre-incubation: eggs may begin to develop if the storage temp is too warm and then the embryos will die as the temp is too low to support continued development, keep the storage temp under 72F or lower if possible!
Acute Trauma: think dropped eggs or accidentally dropping the basket holding them. I packed some eggs in a shipping container trying to mimic shipping damage, I tossed it around and flung it down the stairs several days in a row. No effect on development rates! If the shell cracks, obviously the egg is probably toast (or should be eaten on toast at least). One crazy thing I did notice was when photographing candled eggs, the acute trauma (and geriatric eggs) both had significantly less vein development than control eggs. So your eggs can still develop, but it just places more stress on the developing embryo. So if you drop one or fumble the box around, as long as shells are intact you still have a good chance at hatching them!
Water Candling: floating a developing egg in 100F water and seeing if it moves, bobs, or wiggles to check viability is an option but also comes with inherent risks, if there is any hole or crack in the egg it will drown the chick. I only use it 24 hours after the last chick hatches on unpipped eggs to see if there is any point in running the incubator longer or if we're done and should clean up and put it away. I did try it on my no turn dry hatch on day 14 just to check viability. I had 6/20 eggs that died around day 14, no idea if it was the water candling or the no turning, I did check thoroughly for cracks too. I would recommend not combining it with late term embryos and dry hatching except in very certain circumstances and in general use it with caution.
Open Egg Hatch/Chick in a Cup: this is a science project, google chick in a cup for an amazing video if you haven't seen it yet, time lapse of a developing chick in a plastic cup covered in plastic wrap, it will blow your mind. Another version is to cut the wide end off an egg and cover it with clear plastic to observe embryonic development, obviously a problematic and risky procedure. Using quail eggs was very anticlimactic, I got 0 development and no rotten eggs or bacterial growth either. The surface area to volume ratio on these little eggs is so bad that they dried out (even at 80% humidity) and turned into egg jerky instead of growing chicks or microbes! Don't use little eggs if you delve into this one!
Incubation is a process, be patient with yourself and your eggs, learn constantly and find what works best for you, most of all, enjoy the process! It is amazing what eggs can withstand to still produce healthy and viable chicks!
Just a few caveats here, every attempt hatching eggs is different, even between hatching attempts by the same person, so please don’t take any of the following observations as hard and fast rules, especially as they all involve small sample sizes and often no control group. And while hatching eggs from any species is similar, what works for quail might not be right for guineas or whatever. This is also not verified, statistically significant data, it is merely observations of a private individual goofing around with an incubator. That being said, I have been trained in the scientific process and might even have a peer reviewed study published somewhere so there be a little method in my madness.
Materials and methods: unless otherwise noted, all eggs originated from our small breeding flock of coturnix quail (3 males, 13 females) which originated from a batch of shipped eggs we hatched last March. Our fertility runs at ninety percent or higher, embryonic death is ten percent or less, hatch rates are ninety percent or better on home raised eggs. We used a cheap Amazon incubator for the majority of these trials. Not all eggs were taken to hatch, cull eggs and dead eggs were opened and examined. Infertile eggs were eggs that showed no sign of development and are not counted in hatch rates or considered as part of any trial. Several external hygrometer/thermometer units were used during each hatch. Development means the eggs began to grow, even if they only made it to day 2. Hatch means a live chick that survives outside the shell. Early embryonic death is an embryo that died before or on day 8, late embryonic death is considered day 9 to hatch. Deformed means chicks or embryos with obvious anatomical defects. Coturnix quail hatch day 17 (range 15-20 days) in general.
So what is the most important factor with incubation? If you said incubation temperature, you’re right. Temperature is the one factor that will make or break your hatch. Too cold and eggs won't develop or will hatch late. Too hot and embryos die. I didn't mess with temperature very much, for obvious reasons, but I do have a psycho incubator that runs at 105F and did put a few eggs in there just to see what would happen. Eggs began to develop and died day 1-3 for fresh eggs. Day 3 embryonated eggs were also placed in the incubator for up to 12 hours without any obvious adverse effects (did not take to hatch, temp spikes can be associated with embryonic death and chick deformity), ie they didn't die suddenly but can't comment on longterm adverse effects. The most important aspect of your hatch is to have a several independent thermometer units in your incubator, go by those, not whatever the incubator tells you, adjust said incubator as needed.
After incubation temperature comes turning, as far as direct effect on hatch rates. Not turning your eggs won't destroy your hatch, but you can expect between a 25-50% reduction in hatch rates if you don't. So make sure those eggs get turned at least 3 times daily the first 12 days of incubation! Also move them around in the incubator so if there are cold or hot spots, it gets averaged out instead of exposing a few eggs to it all of incubation.
What about humidity? Strangely humidity didn't seem to effect hatch rates or development, even when eggs were exposed to either extreme (12% or 80%) all of incubation (lockdown was 70-80% for all eggs!). I had both huge and tiny air cells respectively but all the chicks hatched just fine, though anecdotally I thought the extreme dry hatch eggs hatched much more vigorous and lively chicks than the extreme wet hatch (or regular 45% hatches). Takeaway: don't worry too much about humidity, try and keep the average around recommended levels but don't panic if it spikes or tanks, unlike temp it will not destroy your hatch.
The other major factor affecting hatch rates was a pre-incubation factor. Storage temperature (fridge or room temp) and turning (or not turning) during storage made no difference to development or hatch rates. Age of the eggs made a huge difference! Eggs older than two weeks of age at the start of incubation had a 50% mortality rate by day 8, they all developed but then started dying off. You can incubate fridge eggs, just make sure they aren't a couple weeks old. You will get development but your hatch rate won't be great with older eggs.
In some camps, candling is thought to cause issues if done too much. I love the developmental part of incubation and pretty much candle every egg daily, the only issue I ran into was accidentally dropping eggs due to too much handling. So if you are accident prone, maybe minimize handling time, but otherwise, candle away!
Some of the other factors don't deal so much with the eggs themselves as the source, some of which you don't have any control over depending on your situation. I haven't done any experiments with genetics, hen nutrition, etc. and only have anecdotal observations on shipped eggs. There are also a few notes on very specific factors most normal hatchers aren't concerned about (water candling and trying an open egg hatch.) or issues that may arise infrequently during incubation.
Shipping eggs is notorious for causing issues with hatching, between temperature extremes, rough handling, and delayed incubation, a hatch rate of 50% is considered good in most cases. I can only comment anecdotally, on two shipments from different breeders totaling 3 dozen eggs, one was great and one was awful as far as length of time and damage to the package/eggs. In both batches I had a ten percent early embryonic death rate, ten percent late embryonic death rate (20% embryonic death compared to less than 10% on home raised eggs) as well as a ten percent deformed chick rate (0 on home raised eggs). But sometimes shipping is the only way to expand your genetics or even get certain birds (as in my case!), just know it comes with complications!
Genetics, hen nutrition, and fertility are all flock associated factors you may or may not have any control over, but good flock management is key to healthy and successful hatching, wherever you source your eggs!
Heat spikes: 3 day old embryos were exposed to 105F for 12 hours with no immediate effects, but I did not take them to hatch, high temps can be associated with embryonic death and deformity, so proceed with caution if this happens to your hatch, but it doesn't necessarily mean your hatch is doomed.
Freezing: as long as the shell doesn't crack, eggs exposed to cold temperatures preincubation haven't shown a difference in development or hatch rates (I've done both fridge eggs and eggs sitting out in our 32F garage for a couple days).
Warm ambient temperatures pre-incubation: eggs may begin to develop if the storage temp is too warm and then the embryos will die as the temp is too low to support continued development, keep the storage temp under 72F or lower if possible!
Acute Trauma: think dropped eggs or accidentally dropping the basket holding them. I packed some eggs in a shipping container trying to mimic shipping damage, I tossed it around and flung it down the stairs several days in a row. No effect on development rates! If the shell cracks, obviously the egg is probably toast (or should be eaten on toast at least). One crazy thing I did notice was when photographing candled eggs, the acute trauma (and geriatric eggs) both had significantly less vein development than control eggs. So your eggs can still develop, but it just places more stress on the developing embryo. So if you drop one or fumble the box around, as long as shells are intact you still have a good chance at hatching them!
Water Candling: floating a developing egg in 100F water and seeing if it moves, bobs, or wiggles to check viability is an option but also comes with inherent risks, if there is any hole or crack in the egg it will drown the chick. I only use it 24 hours after the last chick hatches on unpipped eggs to see if there is any point in running the incubator longer or if we're done and should clean up and put it away. I did try it on my no turn dry hatch on day 14 just to check viability. I had 6/20 eggs that died around day 14, no idea if it was the water candling or the no turning, I did check thoroughly for cracks too. I would recommend not combining it with late term embryos and dry hatching except in very certain circumstances and in general use it with caution.
Open Egg Hatch/Chick in a Cup: this is a science project, google chick in a cup for an amazing video if you haven't seen it yet, time lapse of a developing chick in a plastic cup covered in plastic wrap, it will blow your mind. Another version is to cut the wide end off an egg and cover it with clear plastic to observe embryonic development, obviously a problematic and risky procedure. Using quail eggs was very anticlimactic, I got 0 development and no rotten eggs or bacterial growth either. The surface area to volume ratio on these little eggs is so bad that they dried out (even at 80% humidity) and turned into egg jerky instead of growing chicks or microbes! Don't use little eggs if you delve into this one!
Incubation is a process, be patient with yourself and your eggs, learn constantly and find what works best for you, most of all, enjoy the process! It is amazing what eggs can withstand to still produce healthy and viable chicks!
