Do not turn eggs??? What do you think???

Discussion in 'Incubating & Hatching Eggs' started by TerrasCritters, Feb 10, 2008.

  1. TerrasCritters

    TerrasCritters In a new coop

    Oct 24, 2007
    Interesting Article Almost Worth Trying It Out
    Break a cherished tradition: quit turning those eggs in the incubator.(hatching poultry eggs)
    Countryside & Small Stock Journal - July 1, 1996
    D.L. Salsbury

    Word count: 1998.
    citation details

    I congratulate Pete Alberda for his article "How To Hatch Eggs In An Incubator" in the March/April issue of COUNTRYSIDE. It contained a lot of very valuable tips and information for those unfamiliar with the operation of an incubator.
    I do not wish to detract from the article in any manner because it accurately reflects the currently popular consensus regarding operation of an incubator, including the necessity to turn the eggs. It is the latter which may be scientifically invalid, and on which I wish to offer comment.
    Myth becomes fact
    It's a documented fact that if one repeats a myth often enough and long enough, it becomes an unquestionable belief. Once attaining this status, it continues to be passed down from generation to generation by word of mouth and in print, even when it may contradict sense and experience.
    Is this the case with the necessity to turn poultry eggs in an incubator once or twice a day? Ask anyone knowledgeable in the field and they will respond emphatically that yes, eggs must be turned daily. However, scientific evidence and common sense do not support this thesis. They strongly suggest that it may be nothing more than a universally accepted myth that has gone unchallenged for more than a century.
    A course in embryology
    Almost 38 years ago, I was an aspiring pre-veterinary student fresh out of the Army. One of the required pre-vet courses was a 5-credit hour class in embryology. This, I was to painfully discover, was the first of a series of "flunk-out" courses designed to weed out the "wannabe" vet students and send them flying to their counselor for a transfer to the "School of Fine Arts and Parties." Academically, it was one tough course!
    The course was taught by Dr. H.T. Gier (PhD). Dr. Gier was the country's leading authority on chicken and coyote embryology (admittedly a weird combination), and was author of the most advanced textbook on the subject of chicken embryology. His experimental work in the field was extensive. One of his discoveries was that a clutch of 100 eggs sprayed daily with testosterone (male hormone) or estrogen (female hormone) during incubation would respectively produce 100% roosters or 100% hens. So, as you might surmise, his beginning course concentrated on the developmental embryology of the chick in exquisitely fine detail!
    A feud between experts
    For over 30 years, Dr. Gier had a running but fairly friendly feud with the Poultry Science Department at Kansas State University. He claimed that not only was it not necessary to turn the eggs, but that it was also detrimental to the developing embryo. At the same time, we were required to take a pre-vet course in "poultry science." The poultry science instructor vigorously argued the opposite stand and made numerous guarded references to the so-called expert (Dr. Gier) at the academic end of the campus.
    Over the years, Dr. Gier had hatched out tens upon tens of thousands of eggs for his class work and his post-graduate students in a commercial incubator with an automatic egg turning mechanism turned off... and, he obtained all his fertile eggs from the Poultry Department. Likewise, the Poultry Department hatched out thousands of eggs from the same source, in the same type of incubators with the egg turning mechanism in full functioning order.
    Well guess what boys and girls. Much to his surprise and much to the ire of the Poultry Department, Dr. Gier's hatching percentage was consistently 6-8% better than that of the "poultry experts." Most of his "batches" had an unheard of 99-100% hatching percentage.
    Birds and reptiles
    Birds are direct evolutionary offspring of reptiles. In fact, the vestigial "scales" can still be seen on their legs (feathers are modified scales also). They also share the reptiles' genetic trait of having nucleated red blood cells and laying eggs. From the age of dinosaurs to the present, reptiles have been successfully hatching eggs for millions of years without turning them by burying them in sand, mud, decaying vegetation, etc. and simply walking away.
    The egg turning myth
    The "turning eggs" myth was one of Dr. Gier's biggest pet peeves. When the course got to the point that we were studying the attachment of the amniotic sack to the internal shell membrane (more on this later), he would devote half a lecture to the subject. His story went something like this:
    Answer these questions
    "How many of you (students) come from the farm and have observed chickens or ducks setting on a nest?" (About a dozen of us raised our hands.) "Under natural conditions, a hen lays her eggs in a concave nest of straw, grass, or plain dirt, right?" (Answer: Yes, we had all seen that.) "And due to the shape of the nest, the eggs naturally roll tightly together, right?" (Answer: Yes.) "Have you ever seen a hen pick up her eggs with her bill or her feet, and turn them one by one or physically arrange them?" (Answer: No, we hadn't.) "And often those eggs in a natural nest are somewhat stuck to the bottom with mud or manure where turning would be almost impossible, right?" (Answer: Yes.) "Now, when the hen has been off the nest and goes to sit back down, she straddles the nest and comes to rest in a series of rocking motions, right?" (Answer: Yes.) "Now, do you think that hen is turning those eggs one by one underneath her, or simply attempting to get comfortable and spread her body and feathers over the clutch of eggs to maximize her body heat area?" (Answer: Geez, I don't know... never thought about it that way.) "Now for you Doubting Thomas's in the class, think about this. A chicken has a grasping foot, it can roost on a limb and could conceivably "grasp" an egg, right?" (Answer: Yes.) "But what about waterfowl? Do you really think a clumsy flat-footed duck could grasp an egg with any dexterity?" (Answer: No, heck, they can barely climb over a short obstacle.) His next question was the clincher, "Would you like to hear how this egg-turning myth got started?" (Answer: Yes, we would.)
    He went on to explain that he didn't know when or where the myth of the hen-turning-the-eggs got started. However, about the turn of the century a college professor in some ag school designed an experiment to prove that hens actually did turn their eggs. (Bad science already. One does not set out to prove his or her opinion; one designs a scientific experiment to answer the question, yes or no!)
    How it started
    According to the story, our illustrious professor whom I shall refer to as "Dr. Turner Glassbowl," put a clutch of eggs in a clear glass bowl with the approximate curvature of a natural nest and put the bowl in a glass enclosed cage. The eggs were marked, so they could tell if any of them shifted from their original upright position. A setting hen was put in the cage and a cadre of students was assigned to observe the hen in shifts, 24 hours a day, until the chicks hatched. Their assignment was to make notes of every observation including how often and how much the eggs were "turned."
    As you might surmise, as the hen would enter or leave her glass bowl nest, the act of walking on them would cause them to rotate in the slick bowl like a bunch of interconnected ball bearings. Furthermore, when she would re-enter the nest and "scrunch around" before settling down, the eggs would again rotate because of this ball bearing phenomenon. There was no evidence that the hen made any conscientious effort to turn the eggs with her feet or bill other than the pressure exerted from her weight in this "frictionless" environment.
    As a result of this "scientific experiment," it was concluded that a hen, under "natural" conditions would turn her eggs twice a day. The results were apparently published and the "facts" subsequently spread by word of mouth. From that day forth the incubator manufacturers added the egg turning mechanism to their products, and "knowledgeable" people in the field began to tell the less knowledgeable that they must turn the eggs while hatching in an incubator. Imagine, all of this from assuming that the events that occur in a slick glass bowl are the same as those that occur in a straw nest. The fable has been told ever since without question.
    Why egg-turning is detrimental
    Now back to the amniotic sack. There is enough air in the egg by natural diffusion through the shell to support early embryonic development, but the chick soon outgrows this meager supply. Additional outside sources of oxygen are desperately needed at this point (imagine trying to breathe through an egg shell).
    This is where the amniotic sack comes in. The amniotic sack is a thin membrane with blood vessels attached directly to the embryo's circulatory system that begins to develop early during gestation (incubation). In a manner of speaking, it is the "lung" for the developing embryo. As it grows, it floats upward toward the inside of the shell. In order to transport oxygen and carbon dioxide back and forth between the inside of the egg and the outside environment, it must attach to the inner lining of the egg. Any excessive movement of the egg/embryo at this critical point is likely to prevent the normal attachment of the amnion to the egg. The short of it is, if the attachment is disturbed or prevented, the embryo will suffocate. These are the fertile embryos that turn black after a week or so.
    This explains why you observe "good" eggs going "bad" during early incubation if you are a hard-core "egg turner." It goes without saying that this is not an all or none phenomenon. Most fertile eggs will hatch no matter how many times they are turned, but it can make the difference between a medium to good hatch and a great one.
    Practical experience
    My wife Betty always has had better-than-average luck hatching duck eggs in an incubator. In fact, her first experience with a borrowed incubator was twice as good as the owner's experience with it. Just to try out Dr. Gier's premise, I ask her (without telling her that I was writing this article), what her procedure was. She said that she turned them several times a day during the first 2 or 3 days just to make sure that they got plenty of water all around and then didn't touch them again except to replenish the water. She also said that she always made sure that the big end of the egg was "up" because that's where the ducklings broke out. (For what it's worth, she also voiced an opinion that she believed that duck hens always lay more eggs than they really intend to hatch, because they use the eggs in the outside ring as a temperature barrier for the eggs in the middle.)
    So much for science, myth, common beliefs and practice. I'm not trying to convert the hard-core egg-turners of this world, just trying to add a little science and common sense to a procedure that mother nature has been doing successfully for millions of years before man decided to "improve" upon it. One thing for certain though, if you purchase a new incubator or ask an "experienced" friend for help, you will most assuredly get advice and instructions based on "Dr. Glassbowl's" scientific discovery!


    Citation Details
    Title: Break a cherished tradition: quit turning those eggs in the incubator.(hatching poultry eggs)
    Author: D.L. Salsbury
    Publication: Countryside & Small Stock Journal (Magazine/Journal)
    Date: July 1, 1996
    Publisher: Countryside Publications Ltd.
    Volume: v80 Issue: n4 Page: p43(3)
  2. CarlaRiggs

    CarlaRiggs Songster

    The egg turning debate is interesting... but I'm more focused on the sprayed hormones he mentioned. If this is true, why don't hatcheries routinely spray more incubating eggs with estrogen? The majority of buyers want females instead of males. It would seem that any hatchery that could boast a highly successful sexing rate would have more business.

    ....Although, I must admit ~ I wouldn't want to work where hormones were being sprayed! [​IMG]
  3. TerrasCritters

    TerrasCritters In a new coop

    Oct 24, 2007
    Good point... I wouldnt want to work around that either LOL
  4. silkiechicken

    silkiechicken Staff PhD

    As usual I am skeptical... All I can speak of is my personal experience. I've had eggs hatch which were turned every 45 min or so by an egg turner, or 3x a day by hand only on week days. If temps are right and enough weight loss occurs in the egg, they will hatch no problem. As for sticking to shells, I've opened a number of embryos 60 hours into incubation, and if I had forgotten to turn the turner on... it was always a pain since they were stuck to the inner membrane and I noted an increase in developmental defects. Could be coincidence, but does agree with how eggs should be turned during the first 3 days so the young embryo only a few hundred cell layers thick does not stick to the shell. Beyond that, generally they can move on their own a bit and aren't "flat."

    For the hormone thing, by spraying them with hormones, it's not going to affect the genotype of the chick. They will still genetically be male or female according to how the egg was fertilized, as adding a hormone won't change the chick's DNA. However, the pheotype of the chick can be changed and it can develop male/female characteristics. That part of the article has me concerned about the validity an interpretation of the initial article.
  5. TerrasCritters

    TerrasCritters In a new coop

    Oct 24, 2007
    I think Dirty Jobs it was, they were incubating Croc or Alligator eggs. The man could incubate the eggs at different temps to produce a female embryo and different temps to produce a male embryo.

    Could it of just been luck?
  6. silkiechicken

    silkiechicken Staff PhD

    That is true with some reptiles that they can change their gender is determined according to incubation temps. I think it has something to do with the epigenetic factors of the reptile's DNA. However, I don't know much about reptiles and don't think it can be replicated in any of the avian species. Isn't there a type of fish that can change their gender if the population isn't in the right balance and even produce fertile offspring? And that they can do this post maturation?
  7. MaransGuy

    MaransGuy Songster

    Oct 25, 2007
    Greenfield, MA
    Although I have never tried it I have heard other people say they do not turn their eggs and have fine hatches. As far as a chick "sticking" to the shell, the chick is never in contact with the shell. There are three membranes between the embryo and the shell that would make sticking impossible. The membranes, themselves, may "stick" but it would be hard to detrmine what is actually going on at the cellular level. Also, while it is true that birds are direct descendants from reptiles, they have also undergone dramatic physiological changes that do not allow one to simply extrapolate assumptions based on their relationship.

    Personally, I can easily see how a myth can become accepted as fact, especially in this case, where you are talking about a practice that has been done for hundreds of years, and began by our ancestors that had little biological understanding at the time. I think eggs can hatch either way. Perhaps this summer I will try a little experiment of my own and see what "hatches"!


    P.S. I am fascinated by embryology and would have loved to take that course!
  8. hensdeliverthegoods

    hensdeliverthegoods Songster

    Dec 18, 2007
    Catawba County, NC
    That is a fascinating article, gives lots of food for thought. I've often wondered myself if temp affected gender with bird eggs the way it does with reptiles. I'm sure if it did we would know about it by now. I haven't started hatching eggs yet, but it's sure got me thinking.
  9. MaransGuy

    MaransGuy Songster

    Oct 25, 2007
    Greenfield, MA
    I have heard the topic of temperature determinating sex in birds quite a few times and it simply does not work that way. Like I said earlier, there have been a lot of changes between reptiles and birds on a physiological level. With reptiles, temperature determination of sexes is an advantage since they do not (for the most part) incubate their eggs. The eggs are buried and left to develop on their own. Warmer nests hatch out more males. This helps them survive through the changing environment from year to year. At an ideal temperature for a given species of reptile you get a fairly even sex ratio. Also, in reptiles, temperature can also effect the appearance of an individual. Higher tmeperatures normally result in greater levels of dark pigmentation. That is why a "High Yellow" male Leopard Gecko is so valuable. You need the higher temps to get the males but it also results in greater amounts of dark pigment in the skin. Cooler temps give you a bright yellow color but they are all females.

    These mechanisms are simply no longer present in birds. All birds (with few exceptions) incubate their eggs and keep them at a very stable temerature. Genetics has taken the place of sex determination. If the temperatures are too far out in either direction the embryo will not survive so sex determination by temperature is no longer useful.

    Regarding the sex being determined by spraying with hormones, I can believe that it would work. I see it as being no different than the occasional hen that loses her ovarian function due to disease or age and then develops cock attributes and even starts crowing. These hen-cocks, though, are not fertile and I doubt that the ones in the study would have been either. Most higher life forms do have both male and femal hormones acting on them and it is the amounts of each that determine their gender. If something goes haywire you can have all sorts of odd-ball results.

    Rearding the fish, silkiechicken, yes that is true about several species. The dominant animal will always be male and it's presence inhibits the tetstosterone release in the rest of the population. Once that male is removed, the suppression is as well and the next dominant female changes into a fully functioning male.

    Last edited: Feb 10, 2008
  10. speckledhen

    speckledhen Intentional Solitude

    Well, I know for a fact they need to be moved around some or they'll most likely die. How do I know this? Someone I know forgot to plug in the turner on an entire bator load of eggs shipped from several different locations. ALL perished and they had candled okay at the beginning. None pipped. So, I would NOT chance that!

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