Where in the world did you read that, Katharina? I am not doubting you have read that somewhere, just curious where. I have never heard dropping the temperature *that* far. I know some very large commercial machines that are computer operated slowly drop the temperature further than what non-commercial sized machines do. Five degrees though is quite a drop, unless it is a highly controlled environment. The commercial machines monitor all sorts of things like gas exchange that are far beyond what the machines most people here would use do.
I should have said 95-97 degrees. I personally keep it at 97. Read it in several books (all of them were published in Germany in German a long while ago) over the years, and we did that in Germany when I was growing up with ducks. I've learned that this helps them to hatch, because they do generate a lot of heat in their eggs. I also realize that many incubators, like the genesis do not give you a choice. I wonder if they have new studies out, because quite honest my information is not new on this matter. I wonder what temperature those Jamesway computerized machines use for ducks. It's incredible what they do and how they promote hatching with gas exchange etc. That may be something to ask John Metzer. There was something on their site, but I don't remember if it stated what temps. I will look at the site right now. Ok, found the page on Metzer. They talk about 97 and 98. http://www.metzerfarms.com/Articles/SingleStageIncubation.pdf
Good that you did say something. I've read this article a while ago and it must flown by mind, because I did not remember the temperature from the article. I was still going by what I knew from old data and what we did when I was younger.
Oh yeah, it has been well known for decades that you should reduce temperature for hatch. There is no question about that, nor any question that the commercial machines reduce temps more than what hobbyists do (but, in a much more controlled environment).
I was just questioning reducing by 5 degrees. That seems way too far to me for the average non-commercial machine. We generally incubate at 99.3 (although 99.5 or so is about what is normally recommended). Even if a person incubates at 100 degrees a 5 degree drop for hatch would be 95. I think that is way too low and would probably result in lots of dead ducklings. There is a big difference between 95 and 97/98. In incubation, fractions of a degree can make a HUGE difference.
I had perfect hatches at 95, but do prefer 97. 5 degrees sound like a lot, but I think the humidity is more important at that stage. Reality is ducks are not that perfect with their temps either, so I don't think a fraction makes any difference. Full degrees probably. In an age of technology we are sometimes to fixed on a perfect number or perfect date that we forget that nature is much stronger. In the old days woman stuffed eggs into their bras for hatching. Even those old contraptions that ran on kerosene worked. Its in a way kind of like cooking. You can measure exactly for just go by what looks, feels and taste right.
My hatcher get set at about 96F but by the time the eggs are in there they increase it to about 104F by themselves but myde home ma hatcher is quite a small one that will take only about 10 duck eggs. And after they hatched out the temperature drops. SO they must really breaking a sweat in the shells... lol