Weight loss % by day 18

[jher77]

I was tracking the weight loss by an average of all the eggs, but now I look at each egg and I see them with a spread of 9% on up to 15% with an average weight loss percentage landing in the 12-13% zone. This got me to thinking that maybe I can shift the percentages one way or the other in favor of the lower or higher percentage eggs or maybe sacrifice one really low percentage egg in favor of lowering the high percentage eggs. Technically with numbers like that, it seems that one may drown (lost too little water) and one may not be able to pip (air cell grew too big).

I can find that 10% is the minimum recommended, but no recommendations on the maximum loss percentage. Does anyone know what the maximum weight loss percentage is?

If anyone has kept track of their weight loss percentages on day 18 and feels like it did or didn't affect the hatch, I'd love to hear some numbers and comments.

I've have these on record: (these are fertilized eggs that made it to lockdown, no clears or blood rings.)
AVG 14.2% weight loss (3 out of 20 didn't hatch)
AVG 12.2% weight loss (2 out of 7 didn't hatch)
AVG 12.4% weight loss (2 out of 4 didn't hatch)
AVG 11.2% weight loss (1 out of 3 didn't hatch)

 

[FoodFreedomNow]

In Pete55's comprehensive Guide to Incubation & Hatching (applicable to all species), he recommends weight loss of "14-17% of their fresh laid weight by External Pipping to produce healthy hatchlings."

I typically watch air cell size and adjust humidity based on that, if needed. I did track weight loss in several batches of goose eggs I set this year, but saw a range of weight loss across the eggs and ultimately decided that the air cell size method was as effective and less labor-intensive (and each time I handled those developing eggs to weigh them, I risked accidental damage to them).

With your eggs that made it to lockdown, were the late quitters always ones that were outside the optimal weight loss range? And what did eggtopsies show?

 

[jher77]

Thanks I'll check that link out. I've had some clears and quitters with every hatch and I wasn't counting those in my figures.

AVG 14.2% weight loss (3 out of 20 didn't hatch) - The three that died lost 8.0%, 6.8%, & 8.7% by day 18. No wonder they didn't make it. The highest ones were 17.6%, 17.7%, 18.1% weight lost on day 18 and they hatched. That is a pretty big weight spread from 6.8% - 18.1%.

AVG 12.2% weight loss (2 out of 7 didn't hatch) - The two that died lost 11.6% & 15.2% by day 18. The five that hatched lost 14.0%, 10.6%, 12.2%, 10.7%, & 10.8% by day 18. Not sure what happened here but the weight spread isn't as much, 10.6% - 15.2%.

AVG 12.4% weight loss (2 out of 4 didn't hatch) - The two that died lost 12.0% & 12.2%. The two that hatched lost 13.1% & 12.1%. Not sure why the two died.

AVG 11.2% weight loss (1 out of 3 didn't hatch) - The one that died lost 10.0% and the two that hatched lost 12.3% & 11.3%.

I didn't really do any eggtopsies. I don't really know what to look for except the chicks were fully formed after I cracked them open. I was just happy with what I had when I started but it slowly got worse. That is what got me looking into it. Good thing I kept some records and don't count your chickens before they hatch.

Looking at my numbers it looks like 10% and 11% weight loss is not good enough. 12% may be border line. 13% on up to 18% weight loss may be best, just what you said. So I see I need to aim for different numbers and lower my humidity.

 

[FoodFreedomNow]

Based on your data, I agree that your future hatches may benefit from lower humidity to get them into the "optimal" weight loss range, but there are a number of other factors that could be contributing to the number of late quitters you're seeing.

This site has information about performing an eggtopsy and troubleshooting incubation issues that you may find helpful. I perform eggtopsies routinely to better understand what occurred with late quitters and find the process very informative.

Kudos for actively trying to improve your hatch rates - I wish you success.

 

[HollowOfWisps]

Do you use pre-calibrated analog thermometers and hygrometers in your incubator? What was your temperature and humidity during incubation?

 

[jher77]

Thanks for that link. Looks informative.

The top hatch was my first hatch. It done well. It averaged 42% humidity. I used water in my incubator to adjust it. It was in November 2020.

The other ones, they averaged 45%, 45%, & 44%. Those should have been lower, maybe in the 38% range. I also used water in the incubator.

I have a hatch going on now (ironically it is November 2021) that I quickly & surprisingly found out that I had to remove all of the water and dry incubate. Didn't have to last year at this time. They are on day 16 now and are on track to loose 10.2% -15.46% weight loss by day 18. Avg humidity right now is 31%. The weight loss would have been higher if I had noticed it sooner. Maybe the egg shells are thicker than they used to be, don't know.

So it appears the incubators humidity will likely never be the same, even with the same incubator, same breed of eggs, same time of year.

 

[jher77]

Do you use pre-calibrated analog thermometers and hygrometers in your incubator? What was your temperature and humidity during incubation?

Yes I do. I am very meticulous about that part.

Filled sink full of 100 degree water and let is stablilize. Stick medical thermometer probe and temp controller probe in the water and record several times and compare.

Hygrometers get calibrated from the sodium chloride test.

They do hatch on time. 21st day.

Forced air. Temp 37.5c. Humidity answered above.

 

[HollowOfWisps]

Yes I do. I am very meticulous about that part.

Filled sink full of 100 degree water and let is stablilize. Stick medical thermometer probe and temp controller probe in the water and record several times and compare.

Hygrometers get calibrated from the sodium chloride test.

They do hatch on time. 21st day.

Forced air. Temp 37.5c. Humidity answered above.

I think the numbers that seem to be everywhere online are too high. I haven't hatched chickens is forever, but with my duck eggs I'm always measuring weight loss and air cell development. My best hatches also had the most accurate weight loss and were hatched with 40-45% humidity. Which again, that's ducks who are "supposed" to require higher humidity than chickens, but my point is I think your on the right track with your humidity needing to be on the lower end. I love home experiments and with getting back into chickens next year I want to slip my small cigar hygrometers under some broody hens to see just how far off the hatching guides online really are.