breeding chickens · Chickens · hatching eggs · homesteading · raising chickens

Warning: Nerdiness Follows – All you never bothered to ask about eggs

Alright this entry is going to be a strange one! Basically I have one laying hen who has given me all sorts of eggs, an incubator who likes making omelets, and a constantly wandering mind. These three things have conspired and created an experiment…

Eggs are strange things. When they are laid they already have the beginnings of a fetus in them (granted its only the tiniest blob of cells.) This new life however will go dormant as soon as the egg gets colder than 80 degrees. This is so mama hen can spend the next few days lying more eggs before beginning to sit on them, ensuring her whole clutch will hatch on the same 1 or 2 days. Its genius. I’m not a biologist but I do know that any fetus will gain in mass when it grows and when it does it’ll also gain in weight. The question is does the egg itself gain weight or does the fetus just convert the goo in there and still remain the same weight all together? Anecdotal evidence tells me that an egg ready to hatch will feel heavier than an egg that has just been laid but humans are not scientific instruments. Maybe the egg feels heavier simply because the mass inside it, a chick, is balanced differently than the goo in the newly laid egg.

I scoured the internet for answers… and at the end of this I realized if anyone had experimented with this concept they weren’t sharing the information. One person quoted Wikipedia, “the law of conservation of mass states that the mass of an isolated system (closed to all transfers of matter and energy) will remain constant over time.” Wiki has lied to me before but this does seem like a legitimate scientific concept. However it brings up an entirely new question – is an egg an isolated system? I mean it looks hard and solid enough but I know an egg in an airless environment will not hatch – this means oxygen is getting past the shell, and humidity is also likely entering and possibly exiting there. If these things can get in and out is it really all that closed?

This is all one question – and God knows I have so many others aching to be answered – but for now I am concentrating on this one. I set out to ask Scientific Method. I labelled my eggs by letter, A-V, and recorded their progress every day on a postal scale that could pick up their weights to the closest tenth of an ounce. I had the incubator set to the right temperature, I turned them every day, and at day 18 I was getting ready to get my answer. At day 23 my house of cards all fell down. My eggs were dead. But how? and why? and when? I charted out my egg weights on an actual chart after googling how exactly you do this on a home computer. It revealed that indeed on day four there was a dip in weights… my incubator went on another killing spree, spiking in temperature and cooking the damn things while I had no idea of what was going on. ARGH. Here’s the chart anyway… it shows that even dead the eggs carried on a very similar trajectory of weights, that indeed did change. In fact that brought up questions of its own. Why for instance did the second and larger dip in weights happen? Why did the eggs go from 0.9 down to as little as 0.3 ounces? And then go back up?? Great now I have more questions, not less!


This second chart depicts the eggs I started popping in as they were laid, figuring this would boost the hatch rate. I’m told they’re still pretty good after ten days and can still hatch after 3 weeks but less will hatch at that point. Because of this I jotted down the dates instead of the days of incubation. The chart looks different because of this but at least its more likely able to tell me when there was mass chick death and again it did. Between Oct 9 – Oct 11 my incubator struck again! ARGH! Currently I only have four eggs being incubated that I believe might still have a fighting chance, of those only one looked promising candled. I think my hen and rooster are tiring out.


Finally this a chart I did of my two hatchlings from the previous batch. I believe Mighty might be a rooster and now looking at his consistently heavier weight I am wondering if this too could be an indication of sex. Need more study subjects……..