Calculating an "honest" hatch rate?

[Wynette]

You know, I believe it's impossible to get an actual 100% certain hatch rate. In my experience, even when you crack what appears to be a clear egg when you candle, you cannot tell whether it was fertile to begin with. They get so runny inside after being in the spa for a few weeks. I've tried and tried to determine if those were infertile to begin with, and unless I'm doing something wrong, it can't be done. Thus, if you received, for example, 12 hatching eggs and two were clear at day 18, and you cracked them open but could not tell if they were fertile in the first place, do you count them? If they WERE fertile, IMO, they ought to be counted. If not, then they shouldn't. Also, what do you do about shipped eggs? It's a known fact that some are lost during shipment due to rough handling, and this should not be counted toward your hatch. So, I think there are just too many variables to get a 100% certain hatch rate.

What I do when I'm posting about a hatch or if someone asks me how my hatch went, I state how many eggs were shipped, how many appeared to be clear at day 18, and of the ones left, how many hatched. What I use as "hatch rate" is the percentage of those that hatched that were developing at day 18. I think you have to decide what you're comfortable with, and maybe explain to folks how you are figuring your hatch rate if it makes you more comfortable to do so.

 

[Akane]

I would rarely ever have a clear left at day 18. Most of my clears are gone at day 7 and 99% percent of them by day 10. The exception being really really dark brown large eggs that require 2 flashlights and patience to candle. At only a little over 1 week old if they were runny it would be because they got scrambled in shipping, rough handling, or something caused a bacterial infection which would make me look at my storage conditions and the cleanliness of my bator. I candle frequently and I break open everything that I think has failed before throwing it out so I have the best idea possible when and why an egg quit or failed to develop. If your only candling day 18 then yea you can pretty much only go off of what is alive at the time unless you do some serious investigative work to try to figure out when they died. That's probably the least restrictive way to calculate hatch rate though. There's so many things you could have done wrong in that time to cause some of your eggs to die. If I start with 2 dozen, accidentally turn my incubator up too high or fail to check my thermometer and kill 1 dozen on day 12, and then only candle day 18 and say the remaining dozen is all I'm counting and get 11 chicks then I could say I've got 11 out of 12 or over a 90% hatch rate. Problem is I only got 11 chicks when 24 were viable eggs (assuming all started to develop). That's a bad hatch rate and a big mistake on my part.

If you just want to see if your hatching conditions are correct though then you would want to take only the number alive at day 18 and the number that hatched. I do compare those 2 numbers frequently especially with the seramas I've been hatching recently.

 

[Ruditchka]

In that case, I guess the ones at day18 which were cracked open and totally clear should be not counted, but the ones who began veining/growing at some point, should be counted as a reduction in hatch rate.?