I'm definitely fearful of it. Do you remember what temp you lowered yours to?
The study I read said that cooling eggs at 24ºC for 6 hrs. at the 16th day of incubation significantly increased hatchability% but it didn't say how much.
Another study was a little more ambitious and cooled for longer periods more frequently and it said chicks in those studies were smaller than in the control group.
I think I'm just going to cool for 2 or 3 hours instead of 6.
I cooled them to 75*F for 6 hrs. I cooled two groups. One group that I used ascorbic acid on and one that I didn't. The one I used it on hatched about 12.5% better then the one I didn't use it on. Although both group that I cooled hatched between 12.5-25% worse then my other two groups. The ascorbic acid I used was in a spray form. I can't remember the concentration of it off the top of my head.
CG1 - Control Group 1 (No Spray, No Cool)
CG2 - Control Group 2(No Spray, Cool)
SG1 - Spray Group 1(Spray, No Cool)
SG2 - Spray Group 2(Spray, Cool)
CG1 Hatch Rate - 87.5%
CG2 Hatch Rate - 62.5%
SG1 Hatch Rate - 87.5%
SG2 Hatch Rate - 75.0%