Gender Determination by Refrigeration

[lazy gardener]

Do you have a fan? If you do, recommended temp is 99.5. If no fan, 102* measured at top of eggs.

 

[VintageLilFarm]

Yes, my new incubator is a Brinsea Ovation 28.

 

[ronott1]

I read a few things saying possibly eggs kept at around 40 degrees for about 4 days being more likely to hatch out females. Obviously not determining gender, as that is obviously already determined but that the males may be more likely to die off, leaving only the females.

There was a snafoo with an incubator I purchased from someone, and I ended up getting a refund. This left me with 30 purchased eggs and the choice to either incubate in my styrofoam incubator, or to wait a week to begin incubating them, when my new incubator arrived.

So, I decided to test this theory. I am also incubating them at one degree lower, and I have also marked more pointy vs. rounder eggs, testing another theory floating around out there.

Has anyone here tested any of these three theories and, if so, what was your result?

- Refrigerating eggs at about 40f for around 4 days
- Incubating at a lower temperature
- More pointy eggs being male vs. rounder eggs being female.

Would be fun to hear from others, and I'll also record my findings here. Eggs were refrigerated for a week exactly, and set today at 12:20pm, so should know by next Tuesday if any took.

I'm not good about culling and I feel terrible when I sell a roo for likely Freezer Camp. Would be so much better if I could just get mostly girls. LOL - - *Tale as old as #FirstWorldProblems, right ?!

I bought fertile eggs from trader joes and whole foods. They had bee at about 40F for 5 days. They hathed out close to 50\50

I would think that the information you have came from "People" on the internet and not from a poultry study.

My prediction is that you will not get what you think and that you will get Quite a bit of cockerels

I am putting this thread in my watch list

 

[lazy gardener]

How many chicks did you get from the Trader Joe's eggs?

 

[oregonkat]

Look through this current thread. Lengthy but quite interesting https://www.backyardchickens.com/th...ndex-experiment.1221626/page-24#post-19975361

 

[VintageLilFarm]

I bought fertile eggs from trader joes and whole foods. They had bee at about 40F for 5 days. They hathed out close to 50\50

I would think that the information you have came from "People" on the internet and not from a poultry study.

My prediction is that you will not get what you think and that you will get Quite a bit of cockerels

I am putting this thread in my watch list

Quite interesting about the Trader Joe's eggs.
What kind of chickens were they?

Is your prediction due to the fact that they were refrigerated? Or that I was considering incubating one degree lower? BOO!

 

[ronott1]

On average, if you have a good hatch, you will have close to a 50% ratio between cockerels and pullets.

What you are trying to do is to kill the cockerels. What happens is that you wind up having a bad hatch ratio with sick and weak chicks hatching.

One thing to consider is that if this worked, hatcheries would do it. The best thing to do is to always strive for the best hatch rate with the healthiest chicks possible.

The chicks are hyline crosses from a brown breed over a white breed. TJs uses white egg laying hens and a brown rooster. Whole Foods used brown egg laying hens and a white egg laying gene rooster.

Pullets:

Cockerels:

 

[yellowherb]

My neighbor gave me some very cold, nearly frozen eggs and I hatched them. I had a lot of early quitters and of course some never even tried. Out of 9 that hatched, 8 were female. That's by no means scientific but just my previous experience. I had also read somewhere about a true study done that also suggested that rooster eggs can not take as low of a temperature. I believe the link to that study is on the Toad thread.

In birds the hen determines what gender each egg will be. If they think the ratio of males to females is wrong they will attempt to add more of the needed gender. In a case of low rooster to hen ratio the hens may decide they need more roosters and produce greater than 50% rooster eggs. In my neighbors case he had 1 rooster over 20+ hens, and his own broody hatches are often filled with rooster chicks and only a few hen chicks. It was his eggs that were very cold and hatched out 8 hens/1 rooster for me.

To support the theory of hens deciding the sex of the needed offspring, I had 1 pair of standard cochins. Out of 6 eggs I hatched from them 5 were female and 1 male. I know this because they were barred and could be sexed at hatch. To me this is the hen saying she wanted more hens around and did not need more than a "backup" rooster. Granted this was a low number of eggs to base my theory on.

I am setting eggs tonight (I hope) that have been refrigerated for months (long story). If they take at all, I do expect to see more female chicks just because of my previous experience.

 

[ronott1]

My neighbor gave me some very cold, nearly frozen eggs and I hatched them. I had a lot of early quitters and of course some never even tried. Out of 9 that hatched, 8 were female. That's by no means scientific but just my previous experience. I had also read somewhere about a true study done that also suggested that rooster eggs can not take as low of a temperature. I believe the link to that study is on the Toad thread.

In birds the hen determines what gender each egg will be. If they think the ratio of males to females is wrong they will attempt to add more of the needed gender. In a case of low rooster to hen ratio the hens may decide they need more roosters and produce greater than 50% rooster eggs. In my neighbors case he had 1 rooster over 20+ hens, and his own broody hatches are often filled with rooster chicks and only a few hen chicks. It was his eggs that were very cold and hatched out 8 hens/1 rooster for me.

To support the theory of hens deciding the sex of the needed offspring, I had 1 pair of standard cochins. Out of 6 eggs I hatched from them 5 were female and 1 male. I know this because they were barred and could be sexed at hatch. To me this is the hen saying she wanted more hens around and did not need more than a "backup" rooster. Granted this was a low number of eggs to base my theory on.

I am setting eggs tonight (I hope) that have been refrigerated for months (long story). If they take at all, I do expect to see more female chicks just because of my previous experience.

Hens can't decide which gender of egg to send out of the ovaries. Each ovum is either male or female from the time that they develop in the the egg. They do not change because this is determined by genetics not hormones.

Note: I believe it is possible for the ovum to change gender if the ovum is exposed to a mutagen...but that is not a good or normal thing to happen.

 

[lazy gardener]

The hen does not "decide". However, the gender is determined by the hen b/c of the chromosomes she carries:

Males are the homogametic sex (ZZ), while females are the heterogametic sex (ZW). The Z chromosome is larger and has more genes, like the X chromosome in the XY system.

So, if the hen contributes a Z, the chick is male. If the hen contributes a W, the chick would be female. I believe some hens are more prone to produce male offspring, and others may be more prone to produce females. If I had one of the latter, I'd be sure to save some of her daughters, AND her sons for future breeders. Also, time of year, and available nutrients may play a role in the likelihood of the hen producing more Z or W ova.