Tracking Egg Weight

[Plip]

The handful of times we've incubated eggs in the past, we've basically "followed the recipe." We set the eggs for the right amount of time at the prescribed temperature and humidity, turned the eggs as directed, and raised the humidity when it was time. We made a few tweaks along the way based on what I read and our own observations, but we didn't know why we did what we did, particularly when it comes to humidity. Still, we've had good luck with respectable hatch rates.

But as I've come to understand a little more about what's going on with the egg, especially during those first 14 days, I decided to approach it a little differently. So my eight-year-old daughter and I are doing a bit of a science project together on our current batch of incubated eggs.

Last Sunday, we weighed the eggs trays (4 @ 70 grams each = 280 grams), and then we weighed all 48 eggs in the trays (a total of 965 grams - 280 grams = 685 grams of eggs). We decided our target for the eggs at lockdown (based on our research) is a 13% loss of weight (which would be 595 grams, rounded to the nearest 5 grams, the accuracy of our scale).

So we made a graph. I drew it on the computer, but printed it out because I thought it would be more meaningful to my daughter if she was plotting things by hand. She found 685 grams at day zero and plotted the point. Then she found 595 at day 14, and she plotted that point, too.

The temperature has been 99.5f and the humidity has ranged between 38% and 42%. We re-weighed today, one week later, and found the total weight of the eggs (after subtracting the tray weight) was 650 grams. I was surprised -- I expected more weight loss. But she plotted 650 grams at day 7, and connected the points. It was clear to both of us that we would need to increase the rate of weigh loss to reach our day 14 goal.

In a way, I'm pleased that an adjustment was required. I think it makes for a more satisfying project for her (for me, too), especially if we get a good hatch rate.

Anyway, I wanted to share our project and how we're approaching it. I'm also open to any input, especially if there's something I've overlooked or am misunderstanding.

My one concern is that if there are eggs that aren't viable, could they be throwing off the weight. I've never candled as it seems disruptive to pull out all 48 eggs individually, and I can't really seem to tell anything anyway with the ones I've tried. So I haven't made any adjustments for bad eggs.

 

[Kruchti]

following

 

[JaeG]

I'll be interested to see how you get on. I've recently incubated a few Coturnix at high humidity (70-80%) and all but one hatched out fine. I'm very bad about doing staggered hatches but so far my Buttons and Coturnix don't seem to be affected. So it has made me wonder, as my hatch rates are the same if I follow the recommendations for humidity. It may be that eggs lose certain amounts of moisture at specific periods during incubation rather than in a strictly linear fashion. It would be really interesting to know for sure. Eggs hatch out in rainforest environments so surely there are certain adaptations that enable the egg to lose the right amount of moisture.

As for candling I've found anything after about 5 days in its very difficult to see anything specific inside the egg, but infertile eggs will glow whereas ones with a growing embryo will look dark. On most eggs you can see where the air cell is (unless they have a dark, inconvenient spot) and you could do random samples to track how they are growing.

A very interesting experiment for sure!

 

[Plip]

I was planning to re-weigh on Wednesday, but Spring Break kind of got in the way and we weren't both around to do it together until today. So we finally re-weighed today (one day before lockdown).

First, I had anticipated that the water reservoir would dry up sooner and the humidity would drop. But I miscalculated, so the humidity stayed right around 40% the whole time (turns out that was just fine).

When we weighed today, the total weight of the 48 eggs was 605 grams. That's a loss of just under 12%, which seems like right where we wanted to be. By tomorrow evening, we should be really close to the 595g/13% goal.

Because the humidity was relatively stable throughout the incubation, it supports JaeG's thought that weight-loss may not be linear. At the very least (and in at least this case), the eggs lost 35 grams in the first 7 days and 45 grams in the next 6 days.

I would have been nice to have had more weighings to see if the weight-loss just gradually increased or there was a period(s) of quick weight-loss.

 

[JaeG]

That would be really interesting to work out. I never hatch in large enough numbers of my quail to be able to measure weight loss but it would be a really interesting experiment to do.

Good luck for a great hatch!

 

[Alaskan]

I haven't weighed any of the quail eggs that I have hatched
...

but I have weighed and charted chicken eggs, and there was a linear loss.

 

[Plip]

We weighed the eggs again before lockdown tonight and they weighed exactly the same as yesterday. A couple of possible explanations for that occur to me:

1. They actually did lose weight, but because my scale weighs in 5 gram increments, it wasn't enough weight loss to register (and we weighed each of the four trays separately, so they could have lost several grams total without it showing up).

2. The eggs had already lost the total weight that they were designed to lose during incubation, and we weren't going to see any more significant weight loss.

I'm leaning toward #2. If that's the case, it suggests that the actual humidity isn't as critical as I had previously thought -- that any reasonable humidity level is going to get you where you need to be and not much further.

That's still a guess, though. It would take more testing to convince myself. There could also be advantages or disadvantages to losing the weight more quickly or more slowly.

The hatch should be Wednesday or Thursday.

 

[Alaskan]

humidity does directly influence weight loss in eggs.Quail eggs just might not be super sensitive to humidity changes because the eggs are so small (so fewer pores) and because quail are from dry environments so smaller pores.

 

[Plip]

@Alaskan, I don't doubt that humidity affects weight loss. What I'm hypothesizing is that there's a plateau. If humidity is lower, you'll reach that plateau more quickly. Higher humidity and it will take longer.

I don't mean that weight loss will abruptly stop at that point, but that it slows down, perhaps significantly.

 

[Alaskan]

I don't understand why it would plateau. Either the pores are still functioning, or they aren't. The egg will continue to try to teach equilibrium with the humidity in the air verses the moisture inside the egg.