My incubation temperature dilemma

Discussion in 'Incubating & Hatching Eggs' started by barra060, Aug 21, 2013.

  1. barra060

    barra060 In the Brooder

    Aug 15, 2013
    Hello to all.

    I'm a newbie here. Earlier this summer my father-in-law gave me most of his flock. One rooster, 21 hens (ten barred rocks and 11 he called black rocks) and 5 little ones. My family and friends are enjoying the fresh eggs, and the children love to go see them as much as possible. We live on the edge of the city, and our land is just five minutes away. Since my rooster is quite "active" with the hens (daddy, what's the rooster doing to that hen - oh he's just playing with her) I started to notice that most of the eggs we were eating are fertilized. Since the eggs are picked daily, none of the hens has a chance to go to broody with them. I decided to try incubating a few of them with a homebuilt incubator to see what would happen. While researching on how to build one, here and other websites, the temp "99.5 F" was mentioned as the "optimal" temp for incubation. However, I couldn't find out where this number came from or why. As I was having trouble regulating the temp to 99.5 degrees with a hot water heater thermostat (I switched to a digital controller), I was concerned about the viability of the eggs. When I was monitoring them, I would see temp spikes up to 105 degrees on really hot days, and was concerned that I had killed the embryos, but a handheld infrared thermometer would show that the surface temp of the egg was around 95-99 degrees. I started to wonder about this number and thought about it from my physiologic and engineering background.

    Physiologically the metabolism of the chick embryo during development is acting as an "engine" and producing heat. What is this internal temperature supposed to be I couldn't find. Anyone know this and how 99.5F correlates to it? However, I think with reasonable temperature fluctuations, this "engine" is providing the necessary heat to maintain viability as the shell is the insulator. What is of concern is that the shell cannot insulate well enough against extreme temps. There was a power outage last weekend and the incubator dropped into the low 80's for a few hours, but the surface temp of the embryos was above 90 the whole time. On the other extreme as mentioned earlier the hotter temps did not change the surface temp that much either. To further experiment on temperature variances, my chickens are helping in my investigation. I decided to leave some of the eggs in one nest to see if one of them would go broody and stay. Well two of them tag team the nest with the eggs, but they will leave the nest for extended periods of time and free range with the rest their buddies. I'll know in a couple of weeks if their less than optimal broodiness will suffice to hatch eggs.

    From an engineering standpoint, maintaining an "even" temp appears difficult with the normal incubator, even with a circulating fan. I have a vertical incubator with the heat emanating from down below and a circulating fan. The walls are made of 3/4" particle board and are reinforced further around the egg racks. The outside of the incubator is definitely cooler than the inside so it is keeping heat in it well. Still I have temperature fluctuations from one level to the other, even though the egg racks have plenty of circulation around them. I have temp probes for all levels, but have seen swings of 5 degrees F between the high and low levels. Thinking of how a hen lays on the eggs, you would probably see temperature variances from one egg to another just by which part of her body is in contact with it and its location in the nest. Time to google the internet...

    I researched and found an article that appears to explain temperature fluctuations and what to expect: Although maintaining an even temperature is better (why rock the boat), maybe this will put to ease some people's concerns about power losses and overtemps. At day 12 I just checked my eggs and saw kicking in the embryo, but the surface temp was around 95 F and incubator temp was not at 99.5F. We'll see in about nine days if my hypothesis is correct...

    BTW, yes probably not the best idea to experiment on my first batch of eggs, but a bad thermostat and a 70 mph wind that knocked out the power for several hours started to force its hand and made me think too much.

    Any comments to my dilemma would be greatly appreciated. Maybe more googling is required on my part...
  2. naightengale

    naightengale Chirping

    Aug 13, 2013
    Rocky Mount VA.
    My Coop
    i find this both fasinating and reliveing and also a bit ironic..
    i myself am dealing with this too...
    and we also built our own homemade "vertical" particale board incubator..
    and we are using a hot water stat. my highs are 100 to 101 and lows of 96. but the eggs temp stays 99.5...strange how that works.. i too was worried we were going to ruin these poor eggs.
    here some pics of my "junkubator" we spent all of $9 (thermostat) to build it everything else was stuff we found FREE.





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