Let's Troubleshoot: 50% hatch rate except...

[meghen]

...when using eggs from another flock!

The Facts:

Test Hatch in January 100% Fertility, 87% Hatch
Every weekly hatch since then: 95-100% fertility, 50% Hatch
All eggs candled immediately before lockdown, very average aircells
1 Rooster (2 years old) over 7 hens (2 - 2 year, 5 -1 year)
Eggs carefully selected every week for proper shape/size
No eggs over 7 days old
Eggs stored in cartons, pointy end down, rotated once daily. (Ambient temperature less than 18 degrees celsius- no more than 64F)
Ancient Sportsman Incubator
Hovabator 1588 as hatcher
Have tried hatching on sides in "natural positions" and also upright in cut down egg cartons. Hatch rate unchanged.
Hatched out some EEs for a friend and got a 100% hatch on them.


I'm totally stumped! Why on earth would everything be looking really good until day 18 and then poof! 1/2 the batch dies? And why would our test hatch in January look so promising? I've done eggtopsies on all birds from only two of the failed hatches, but don't really know what to look for. Only a couple out of each eggtopsy have broken the membrane, one was upside down, a few still had lots of yolk unabsorbed.

Does anyone want to take a crack at solving this one with me?

Thanks,
Meg

 

[lazy gardener]

Here are my guesses:

1: your rooster or even several of your hens, while still fertile are getting to the end to the end of their productive time frame. More genetic failures towards the end of the reproductive cycle.

2: Your flock are missing some necessary nutrients.

The unabsorbed yolk leads me to believe that your humidity was too high, or the temp was too low. But that doesn't account for the reason why you had a good hatch of the EE. Did you hatch from this flock last year? Same rooster? Good hatch results?

This is a good read, and might help you:

http://ufdc.ufl.edu/UF00008570/00001/1j

 

[meghen]

Thank you for reminding me! I meant to mention that my flock is fed 16% layer pellets in the morning and scratch before bed. Plus kitchen scraps and anything they can find that looks tasty on 5 acres. The hens average 6 eggs a week apiece.

I had bred the rooster and the 2 elder hens last season with no difficulties maintaining an 80% rate... and the test hatch just utterly befuddles me.

I have posted an ad looking for a new BR rooster in my neighbourhood, we'll see what I can come up with.

Thanks!
Meg

(PS: I have a printed copy of the problem analysis at home, it just seemed that there were so many potential variables that I might do better to check with real humans who could ask probing questions)

 

[lazy gardener]

Meghen: If your flock is getting one feed of 16% in the morning, and scratch at night, I'm guessing that they are not getting adequate nutrition. You might try putting them on multi-flock (20 - 22%) protein, and a good poultry vitamin for a couple of weeks, and then setting an other batch of eggs. II'm guessing that will fix things up for you.