Small air cells and poor hatches


10 Years
Jul 30, 2009
Charlotte, NC Area
Disclaimer: If you are new to hatching & incubating, you may wish to ignore this thread. Hatching is really quite easy most of the time, and you probably don't need to know any of this in order to have reasonably successful hatches, and this thread is likely simply to confuse and discourage you. I would never want to discourage anyone from trying, because it's fun and educational and really not hard most of the time.

On the other hand, if you're having trouble with hatches or just ready to talk about intermediate incubating concepts, maybe there's something in here that might help you, or maybe you have thoughts and experiences that I can learn from.

So. I've been preaching all summer about the importance of proper air cell development during incubation, and my belief that in many cases the recommended incubation humidities for the first portion of incubation are too high, especially for ducks. Since I began incubating duck eggs in the teens and twenties, I have increased my hatch rate considerably. Additionally, my one small hatch that ran at a high humidity this summer hatched out only 60% of the eggs (compared to the 85-95% hatch rates I'm accustomed to).

Now, I can't pretend to speak to every situation. I believe it's highly likely that in dry climates, a higher humidity is called for in the incubator. However, I am more convinced than ever that the standard recommendation for humidity is way too high for my situation and probably many others.

Sadly, my new evidence comes from a batch of 21 eggs from which only four hatched. This is BY FAR the worst hatch I have ever had, and I'm very sad about it. However, I did not fail to learn something from the hatch, and what I learned further supports my theory regarding humidity.

First, of the 21 eggs, there were five with normal air cells. The remainder had air cells that ranged from too small to WAY too small. Most were definitely living at lockdown, though some were questionable.

Of the four that hatched, ALL were among those with fully developed air cells. The ONE egg with a normal air cell that did not hatch was the one whose air cell was smallest of the five normals.

Of the remainder, most of the ducks were fully formed. A few had died slightly before lockdown, based on developmental stage. Of the fully formed ducks, a few had pipped the internal membrane but only the tip of the bill was outside the membrane, indicating probable drowning. Most of them never pipped internally.

I do not have a clear explanation for the ducks who were not fully developed, which were a slightly larger number than normal for me. I don't think it could be disease in the flock, because the eggs were from two separate flocks and the deaths were spread evenly between both batches. It could be a disease in my incubator, though I practice careful hygiene (chlorox washes after every hatch plus hydrogen peroxide in the water wells at the beginning of each incubation), and it would not explain why the air cells were underdeveloped and so many birds pipped internally but not externally.

In any event, the rest of the evidence points strongly, in my mind, to the problem being the small air cells.

The next question, of course, is WHY I had such small air cells. Unfortunately, I do not have a record of the humidity in the incubator. Because I have had such outstanding success with very low humidity and because the low humidity is the norm when not adding water, I had stopped measuring humidity several hatches ago. I now regret that. What I *do* know, however, is that this batch was incubating during a period when the weather was very, very humid and we were not running the air conditioning. The humidity in our house was 45%.

The air conditioning is now running, and I am now measuring humidity in the incubator at all times and making notes of anything unusual. I also plan to monitor the air cells and to spray with warm water daily to help with the evaporation (for those who don't already know this, spraying with water has the opposite effect of high humidity--it actually causes the air cells to develop faster, the way that lower humidity does) if the air cells seem to be developing slowly.

I'll continue to collect data, but would love to hear other's experiences, and any discussion or thoughts on the topic.

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