Refrigerated eggs experiment complete!

[NatJ]

Now I'm hearing you say that temperature can change whether an egg produces a female or male chick?

No, not quite.
The same egg will not produce a different gender of chick.

But some people have suggested that the fridge might kill not-yet-developed chicks of one gender while leaving the other gender alive to hatch. So it would look like only half of the eggs hatched, but the live chicks would be mostly one gender. (So far, it doesn't look like it works very well.)

 

[Kglassmo]

Kglassmo,

very interested in your POV re ConnieA’s comment. Is the production of M/F genetically predisposed? I wonder if, cumulatively the stats would be 50/50, but isolated hens (or people for that matter) would produce M/F more frequently.

Does this question make sense or am I being too vague?

I’m not sure if you’re referring to parthenogenesis? That can happen in reptiles, fish and some amphibious species, but I don’t think it’s common in birds/poultry. Thats when an isolated female with no dominant male presence produces a viable clone of herself within an egg. Those are always female. But, to my knowledge chickens are not capable of this.

In poultry, female chickens carry dominant genes for physical traits, that’s why we have sex-linked traits. Females (ZW) and males (ZZ). Opposite of humans- sperm in chickens is not the determining factor, female genes decides. roosters do not determine physical characteristics.
However, poultry gender is not determined by this. In my hatches under ‘standard favorable conditions’ it was always nearly 50/50 male:female.
The poultry egg industry has been looking for ways to determine gender before or by day 11 incubation to prevent unnecessary hatching of male chicks. In egg industry around 6 billion day old baby roos are killed yearly; roosters are not needed in egg-laying industry. Hens lay eggs regardless of male presence, all infertile.

In egg industry, when fertile eggs are needed to produce new layers, young hens are inseminated by AI. Eggs are set/incubated by humans. So, day old baby roos are sent to be ground up into ‘organic’ pet food. The hope would be chick sex determination could be made well before hatch by PCR/ genetic sampling taken in a sterile, non invasive method but it’s yet to be figured out to standards, food grade testing, etc.. If it was as easy as increasing/decreasing incubation temperature that would have already been happening around globe to reduce production of male ‘egg laying’ breeds of chicks that are brought to life only to be killed within 24hrs. It would be more humane not to allow these baby roos to hatch within egg laying industry to save unnecessary suffering. Not to mention how much money it would save for poultry industry and reduce global carbon print....

 

[NatJ]

In egg industry, when fertile eggs are needed to produce new layers, young hens are inseminated by AI.

Do you have a source for that?

I thought natural mating was the norm, for broilers and layers both, because it requires so much less human labor.

(A hen needs to mate or be inseminated approximately once a week, or more, to keep producing fertile eggs.)

 

[Kglassmo]

Do you have a source for that?

I thought natural mating was the norm, for broilers and layers both, because it requires so much less human labor.

(A hen needs to mate or be inseminated approximately once a week, or more, to keep producing fertile eggs.)

Broilers become ‘too heavy’, overweight, or suffer from hip dysplasia by age of fertility (approx 22 weeks or 5 months) so it’s rare for a broiler rooster to succeed in mounting a female. Instead, broiler roosters ‘donate’ sperm with help of handlers which is then used to fertilize mature hens by AI. It is more cost effective for humans to use AI in broilers, regularly, than try to get a few obese roosters to try and succeed. Broilers are selectively bred to have large muscle mass/ breast tissue, so of course they’re all too heavy. Would likely not be a good fertility rate to say the least. Most broilers go to market at or before 8 wks while they’re still ‘chicks’ and not near egg laying age. ‘oven roasters’ might be 12wks old...
Rooster sperm survives under normal conditions, for up to 7 days inside hen due to pockets/folds inside uterus; multiple sperm donations from several roosters can stay there so paternity is ambiguous if the hen is exposed to multiple rooster sperm.

 

[Kglassmo]

I've read that most hens, and most flocks overall, produce equal numbers, but that some hens do produce more offspring of one gender than the other.

I have not read how common such hens are, but they must be fairly rare, or we would all know about them.

For a hen that produces mostly daughters, do her daughters do the same? I'd love to know, but if it has been studied, I have not been able to find it.



Chickens definitely have sex chromosomes, ZZ for male and ZW for female.
We know this determines the gender, because there are several useful genes on the Z chromosome. They are used to produce sex-link chicks, where the two sexes are different colors. When the father has the recessive gene, and the mother has the dominant gene, then the daughters show the recessive gene while the sons show the dominant gene but also carry the recessive gene. This works so reliably (millions of chicks per year!) that we know there is no other sex-determination mechanism commonly affecting chickens.

Also, a temperature-dependent system would not be very useful to a creature that incubates the eggs, because the eggs always do get incubated at the right temperature in nature.

So even though crocodiles are interesting relatives, chickens don't work that way.

People have experimented with whether higher or lower incubation temperatures would selectively kill one sex of chick, but so far it appears that both sexes die at about the same temperatures, so it's not useful at the backyard or commercial scale.

When you copied my quote I was referring to ‘incubation temperature’ when I said I didn’t

I've read that most hens, and most flocks overall, produce equal numbers, but that some hens do produce more offspring of one gender than the other.

I have not read how common such hens are, but they must be fairly rare, or we would all know about them.

For a hen that produces mostly daughters, do her daughters do the same? I'd love to know, but if it has been studied, I have not been able to find it.



Chickens definitely have sex chromosomes, ZZ for male and ZW for female.
We know this determines the gender, because there are several useful genes on the Z chromosome. They are used to produce sex-link chicks, where the two sexes are different colors. When the father has the recessive gene, and the mother has the dominant gene, then the daughters show the recessive gene while the sons show the dominant gene but also carry the recessive gene. This works so reliably (millions of chicks per year!) that we know there is no other sex-determination mechanism commonly affecting chickens.

Also, a temperature-dependent system would not be very useful to a creature that incubates the eggs, because the eggs always do get incubated at the right temperature in nature.

So even though crocodiles are interesting relatives, chickens don't work that way.

People have experimented with whether higher or lower incubation temperatures would selectively kill one sex of chick, but so far it appears that both sexes die at about the same temperatures, so it's not useful at the backyard or commercial scale.

Please note I was referring to incubation temperature in that quote of mine, as far as determining poultry gender. Not ZZ/ZW chromosomes. We love our black sex link hens, and specialized feathering on our Cochins. Incubation temp determining gender was point being discussed. Chickens are not crocs, just ancestral relatives. Thought it was an interesting connection. It would be too easy if one could determine poultry gender by incubation temp....industry would have been doing it yrs ago. Unfortunately there’s too high a mortality rate.

 

[Orpingtons Mom]

Not the same roo for both clutches, but that doesn't matter, because the hen's genetic contribution determines the sex of the chicks.

Really! I did not know that. So, it the trait heritable?

 

[333113]

Really! I did not know that. So, it the trait heritable?

I think it might passed along, but probably in a roundabout way. Maybe those hens just have more viable boy genes than girl genes, or maybe the hen's reproductive system is better for one sex or another. So, it might be like this study for people, where they found men with more brothers produced more sons:
https://www.sciencedaily.com/releases/2008/12/081211121835.htm

I haven't seen any research on chickens that produce more girls or more boys in families. I do have some of each in my single comb Nankins, but I don't notice it in my other breeds. I guess it's a more important trait to a backyard breeder than to commercial breeders.

 

[Rose Quartz]

I suppose I'm coming to this a bit late.

I store all my eggs from nest box to fridge. And I still get about a 60 -70 % male hatch almost every time.

 

[NatJ]

Broilers become ‘too heavy’, overweight, or suffer from hip dysplasia by age of fertility (approx 22 weeks or 5 months) so it’s rare for a broiler rooster to succeed in mounting a female. Instead, broiler roosters ‘donate’ sperm with help of handlers which is then used to fertilize mature hens by AI. It is more cost effective for humans to use AI in broilers, regularly, than try to get a few obese roosters to try and succeed.

For mass production of broiler chicks, they just semi-starve both genders through their entire growth period so they do not develop the big breast.

You can download the "parent stock management guide" for several lines of broilers (or layers) as a .pdf. Some of them have charts showing what breast shape is desired for the breeders, and indicating how much to increase or decrease feed if it's not right.

Some companies even make special feeders for only the males (taller birds) or females (smaller head/comb/wattles) so they can give them different diets! Here's a link to one example:
https://www.bigdutchmanusa.com/en/p...breeder-management/feeding-systems/malechain/

The selective breeding of broilers (to develop better lines of birds) MIGHT require artificial insemination, but mass-producing broiler chicks certainly does not. And the companies have thoroughly separated those two parts--develop several good parent lines, then raise lots of the parent stock to cross in specific combinations, then raise enormous quantities of chicks from them to actually butcher (broilers) or produce eggs (layers.) They are all using 2-way or even 4-way hybrids, so they never pick a bird that was actually raised as a meat bird and expect it to reproduce.

And if they're not using AI for broilers, they're certainly not using it for the layer types.

Rooster sperm survives under normal conditions, for up to 7 days inside hen due to pockets/folds inside uterus; multiple sperm donations from several roosters can stay there so paternity is ambiguous if the hen is exposed to multiple rooster sperm.

Not a problem in a breeding program that is carefully developing new traits: one rooster per pen, with some number of hens.

Not a problem when producing thousands and millions of chicks: every rooster is an acceptable father for this purpose, and no chick from this pen will be used for breeding.

And the sperm CAN survive for up to 3 weeks--good fertility for the first week, then declining for the next 2 weeks or so. That matters any time someone switches roosters in a breeding pen, so it's pretty well known.

 

[Gatita]

I've read that most hens, and most flocks overall, produce equal numbers, but that some hens do produce more offspring of one gender than the other.

I have not read how common such hens are, but they must be fairly rare, or we would all know about them.

For a hen that produces mostly daughters, do her daughters do the same? I'd love to know, but if it has been studied, I have not been able to find it.



Chickens definitely have sex chromosomes, ZZ for male and ZW for female.
We know this determines the gender, because there are several useful genes on the Z chromosome. They are used to produce sex-link chicks, where the two sexes are different colors. When the father has the recessive gene, and the mother has the dominant gene, then the daughters show the recessive gene while the sons show the dominant gene but also carry the recessive gene. This works so reliably (millions of chicks per year!) that we know there is no other sex-determination mechanism commonly affecting chickens.

Also, a temperature-dependent system would not be very useful to a creature that incubates the eggs, because the eggs always do get incubated at the right temperature in nature.

So even though crocodiles are interesting relatives, chickens don't work that way.

People have experimented with whether higher or lower incubation temperatures would selectively kill one sex of chick, but so far it appears that both sexes die at about the same temperatures, so it's not useful at the backyard or commercial scale.

Last summer my Silver Sebright (bantam) got broody ( a frequent occurence for her, although they are descibed as being non-brody & bad mothers). At the time I had 4 of her eggs in the fridge & had 2 on kitchen counter. So to humor her, I gave her all 6 to set on (4 refrigerated & 2 room temperature) On day 20, 4 of them hatched (the other 2 eggs never hatched & there was no chick development in them). She was a wonderful little mama. Her little foursome ended up being 3 male Silver Sebrights & one female Golden Sebright (the dad was a golden Sebright). So, at least 2 of them were refrigerator chicks. I was the middle of summer & hot outside while she was setting, but I doubt that it had anything to do with their genders