Air sac determines sex.

[horselover1999]

The conclusion of the study mentions one of the other points that I see as a big problem, the small sample size:
"In this study, a total of 60 used eggs, and only 47 of them were hatched. This number is comparatively low, and a large number of data is needed for better results."

And I also see a problem with them training the computer on those 47 chicks, then having it predict the sex of those SAME chicks to check the accuracy. So even with all the right answers, the computer had a pretty low accuracy (better than random chance, worse than the usual after-hatch sexing methods.)
"37 out of 47 (0.787) chicks were classified correctly."

(Quotes are from the previously linked study:
https://pmc.ncbi.nlm.nih.gov/articles/PMC9832119/)

I'd like to see further research on the matter, to prove out whether it really does or does not work. My bet is that it won't work, but proving it one way or the other would be better than forever wondering. I don't personally care enough to do controlled experiments.

In every research project I have been a part of or conducted, I have always wanted more data, even if we thought we raised enough birds to get enough samples.
Less than 50 eggs hatched is a pretty small population to start with.
For my honors thesis, we set the same amount of quail eggs for 4 different bloodlines (a lot of eggs per line, I forgot how many, hatch rate wasn't a part of the study.) One of the lines didn't hatch well, and we almost had to modify the sample size based on that line because we only had so many surviving birds when it was time to draw blood.

 

[horselover1999]

One of the hallmarks in research is whether your data can be repeated by another investigator. If not, I also call BS.
Additionally the original research appears in a low Impact Factor journal.

(Research scientist in another field).

It looks like a grad student and their mentor that published it. That is the first author's only pubication, and the second author has a lot of publications that are all over the map.

 

[Boop2006]

Logically, this makes no sense. I have found that the air sack can vary based on individual hens, the shape of the egg, and how the egg is stored. I have no rooster, so zero chance of fertility. It is my understanding that the male determines the sex of the offspring, so if this theory were true, why would air sacks in infertile eggs vary that much? I do hope, however, since you are incubating anyway that you keep a record, and keep us posted. If it is true, what a Boone to those of us that can't keep roosters.

This study, as well as other articles I have read, indicates the male does not determine the sex of the chick. This is determined by the female. It compared the sex determination process to that of bees. The queen lays the eggs. According to what the larva are fed, a drone, queen, or worker bee will hatch. A hive will have different size cones and the queen measures the cones with her antenna before laying an egg. If a queen dies, the workers will select an egg/larve and begin feeding and prepping it to become the next queen. It sex is determined by conditions, not sperm. Many insects reproduce in the same way, per the articles I have read. It's worth a shot, at any rate. Just trying something old/new.

 

[Boop2006]

If it sounds too good to be true, it probably is.

But what if???!!!

 

[Boop2006]

Do you have a link to this study?
Where did you get this booklet?

Did you trace the air cells on all the eggs, and can you post pics of them??

The booklet is titled How to Tell the Sex of an Egg Before Incubation by Thomas Quisenberry. If you google that, select the USDA article. Click on 'full Article' and you can read the book. It is also available on Amazon. I actually stumbled across it while getting ready to set up my incubator. It's been a few years, so I was brushing up in the process. I will post some pics of my findings later. I will say there are differences in the air sac placement and oddly enough, the old tale of rounder eggs and the side air sac match up in a lot of the eggs. I just hope I don't wind up with 21 roosters!! ; )

 

[Boop2006]

The conclusion of the study mentions one of the other points that I see as a big problem, the small sample size:
"In this study, a total of 60 used eggs, and only 47 of them were hatched. This number is comparatively low, and a large number of data is needed for better results."

And I also see a problem with them training the computer on those 47 chicks, then having it predict the sex of those SAME chicks to check the accuracy. So even with all the right answers, the computer had a pretty low accuracy (better than random chance, worse than the usual after-hatch sexing methods.)
"37 out of 47 (0.787) chicks were classified correctly."

(Quotes are from the previously linked study:
https://pmc.ncbi.nlm.nih.gov/articles/PMC9832119/)

I'd like to see further research on the matter, to prove out whether it really does or does not work. My bet is that it won't work, but proving it one way or the other would be better than forever wondering. I don't personally care enough to do controlled experiments.

It was 1921 after all. We barely had qualified medical doctors at that time. I appreciate the input. It will not be a great waste for us as we will enjoy those top air sac eggs with bacon and toast. Just a fun experiment for a backyarder.

 

[MysteryChicken]

The booklet is titled How to Tell the Sex of an Egg Before Incubation by Thomas Quisenberry. If you google that, select the USDA article. Click on 'full Article' and you can read the book. It is also available on Amazon. I actually stumbled across it while getting ready to set up my incubator. It's been a few years, so I was brushing up in the process. I will post some pics of my findings later. I will say there are differences in the air sac placement and oddly enough, the old tale of rounder eggs and the side air sac match up in a lot of the eggs. I just hope I don't wind up with 21 roosters!! ; )

Check out the sexing method I posted, & use. It's a method I came up with, & it's pretty accurate.

 

[NatJ]

This study, as well as other articles I have read, indicates the male does not determine the sex of the chick. This is determined by the female. It compared the sex determination process to that of bees. The queen lays the eggs. According to what the larva are fed, a drone, queen, or worker bee will hatch.

I don't think that author should have compared chickens with bees. They aren't really the same, and most people don't know bees any better than chickens, so it would be easier to just explain chickens without the comparison.

In chickens, sex is determined by sex chromsomes. Males have ZZ, females have ZW. The female determines the sex of the chick by giving either a Z chromosome (chick will be male) or a W chromosome (chick will be female.)

That is backwards of people, where females have XX and males have XY, and the male determines sex by whether he gives X or Y.

Bees are different yet. Females have XX, males have X and nothing. When a queen bee lays a fertilized egg, it has one X chromosome from her and one from the male, so it is XX which is female. When a queen bee lays an unfertilized egg is has just one X, so it develops into a male. After the egg hatches, feeding the female larva will determine which ones grow into workers and which ones grow into queens. Drones are male no matter how they are fed. There are a few odd cases where XX males exist, but it's due to something specific about the genetics, not how the larva are fed. X/nothing males will never be females.

There are other sex-determination systems too.
https://en.wikipedia.org/wiki/Sex-determination_system
It's rather fascinating, but also confusing!

A hive will have different size cones and the queen measures the cones with her antenna before laying an egg. If a queen dies, the workers will select an egg/larve and begin feeding and prepping it to become the next queen. It sex is determined by conditions, not sperm.

Male vs. female in bees is determined by sperm or lack of it, not by raising conditions. Fertile female (queen) vs. infertile female (worker) is determined by conditions as it is growing.

 

[NatJ]

It was 1921 after all. We barely had qualified medical doctors at that time. I appreciate the input. It will not be a great waste for us as we will enjoy those top air sac eggs with bacon and toast. Just a fun experiment for a backyarder.

When I complaind about the small sample size, I was talking about the 2023 study that used computers to sex eggs by the external shape of the shell, that someone had linked to. I put the link in my post too, hoping to avoid any confusion about which study I meant. I just went back and edited my post to make it more clear for anyone else reading this thread.

The one you mentioned in the first post, from 1921, I think is about something that just does not work. The strongest evidence for that: it's been many years, and it has NOT been widely adopted by hatcheries. If it really worked well, it would have been in common use by now, the way vent-sexing is.

About the sex determination of bees vs. chickens, a post of mine that you didn't quote in that response, yes you have a good point that the author was writing in 1921 and they didn't know as much. In the light of modern knowledge, we can say that author was just plain wrong about some of the sex-determination mechanisms involved.

 

[giakaris]

I have read the study some months ago and I intend to try. But I do not incubate lots of eggs. It would be extremely interesting if some anatomical features are sex varied and how early. From memory I think gonads vary at around 9 days but we are talking for miniscule differences and the tissue is soft. I would be greatly interested if someone has hard data on skeleton features sex diversified early on incubation. Then seeing into the egg is trivial and depending on the degree of diversification may be doable from a amateur budget.
Msc in microelectronics and image processing.