Mortality rate?

[Joduck]

I have been incubating some chicken eggs for a friend - and although I have a high fertilisation rate of about 70/80%, I am having a high early mortality rate.
The first round only one made it through to the end, and then I was busy on the day of hatching and it died about 1/3 way through zipping (I feel terribly guilty as perhaps if I was there I could have helped - but equally I hate interfering for worry of doing so too early). The second round of 11 fertilised, at 15 days in I have 2 definitely and 1 unsure remaining.
This time as I was unsure of myself I cracked open the ones I was discarding - they were all fertilised and all died at about the same time - looking at charts I’m thinking about day 5/6.
The moma chickens are all healthy, a variety of breeds, though all probably a good few years old now (maybe 3/4), with the youngest being 18 months - 2 years. They are free range with a varied natural diet and supplemented with chicken feed.
I candle somewhat regularly - but this time round I have been much more hands off as I was worried I had caused the low rate previously, candling irregularly, every 3/4 days, rather than almost daily like the first round.
Is this normal? Is it something I’m doing wrong? Is it the age of the birds? Is it the incubator? Could it be something else wrong with the birds?
I know natural incubation is best, but we have struggled to find a broody hen and abandoned nests, and other hens trying to get involved (they don’t have a separate area to nest), so we have had a really low natural rate.
Any advice/input would be much appreciated.
Thank you

 

[sourland]

Have you calibrated/checked the temperature and humidity sensors on the incubator?

 

[Joduck]

Have you calibrated/checked the temperature and humidity sensors on the incubator?

I don’t know that it has humidity settings, and I wouldn’t know where to start with calibrating the temperature… I can stick a thermometer in there and see if it reads true as a start.
It’s not an expensive machine, though not super cheap either…

 

[Kiki]

I don’t know that it has humidity settings, and I wouldn’t know where to start with calibrating the temperature… I can stick a thermometer in there and see if it reads true as a start.
It’s not an expensive machine, though not super cheap either…

Never trust the readings on an incubator.
Always purchase separate instruments. I highly recommend these:

Get the 3 pack.
https://www.amazon.com/Govee-Hygrom...8&psc=1&mcid=c4ad6f54c63c327eb6c11a03e7c6ba30

 

[EggSighted4Life]

Any advice/input would be much appreciated.

You don't state what temperature or humidity you're running at and whether you're using still or forced air incubation.. and how often you're turning or if that's automated.

Possible causes of embryonic mortality start around page 51 in the following link with other specific possible hatching issues seen there shortly after..

https://www.hubbardbreeders.com/media/incubation_guideen__053407700_1525_26062017.pdf

 

[Der Vogelhof]

That’s too much candling. You don’t need to candle except to determine viability and then maybe at day 15 to see if they are on track. The others covered the other major issue with your incubation. If you don’t have an auto-turner, turning eggs 5x per day for the first trimester helps fertility in my geese, my chickens have auto-turn so I’m not sure but you could try that.

 

[Joduck]

You don't state what temperature or humidity you're running at and whether you're using still or forced air incubation.. and how often you're turning or if that's automated.

Possible causes of embryonic mortality start around page 51 in the following link with other specific possible hatching issues seen there shortly after..

https://www.hubbardbreeders.com/media/incubation_guideen__053407700_1525_26062017.pdf

Temperature is 37 degrees celcius (98,6f), and humidity doesn’t tell me. I don’t think it controls that. There is a fan that moves air around, and three bottles attached to the unit that I fill with water. It auto turns. I will have a look at the link, thank you.

 

[Joduck]

Ok, so I’ve discovered that the humidity is the first red flag.
It was way too high (way way too high at over 90%). The temperature reads true at 37 degrees Celsius though.
Having removed all water from the unit I’ve brought it down to 45%, which is around the ambient humidity for the room it is in. It is going to be more difficult to raise it to the correct level when needed. But with close monitoring perhaps I can make this unit work.