The book
" A Guide to Better Hatching" by Janet Stromberg recommends temps at below 60, with ideal at 50 degrees, and of course turned as they are held.
Above 60, the embryo struggles to life, and that internal timer begins to tick, and after a while, the embryo gives up, leaving you at best, a bloodring.
I LOVE this book, and read it every year ! Even after raising chickens for 40 years !
(OK OK For 50 years.........
)
Optimal egg storage condition After oviposition the development of the embryo which started in the hen’s body, has to be stopped. Therefore the egg should be cooled down below “physiological zero” (26 – 27 °C) (Funk and Biellier, 1944). This process usually happens inside the nest or on the egg belt. If the ambient temperature is higher (which is not uncommon during summer months), delayed cooling may be a problem. In this case eggs should be collected more frequently to assure that the temperature of the embryo is brought down from 40 °C body temperature to 26-27 °C within six hours. A temperature in the 37-27 °C range leads to unbalanced development and hence early embryonic mortality. Too quick cooling may also weaken the embryo. Further research is needed to determine whether this is due to retarded development or other factors (Schulte-Drüggelte and Svensson, 2011)
DesertChic: It seems the web site you have shown, is describing how to tell a fertile egg, and how to develope it into a chick.
What we were discussing is how to prevent the embryo from developing, and proper handling of these eggs until we set them for incubation.
Unfortunately, once the eggs are exposed to warmer temps, that embryo will try to develope, and that is why eggs need to be held under 60 degrees, then warmed breifly at room temps, and then set in your incubator.