Gender Determination by Refrigeration

[VintageLilFarm]

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 ?!

 

[Queensilkie]

This sounds really interesting! I'll be excited to see if those old wives tales have any weight to 'em. Good luck with your eggos!

 

[AlleysChicks]

I stored eggs in the fridge for 4 weeks and longer. They are 10 weeks old now. Lots of boys.

 

[Dawnclucks22]

The temperature thing isn't true, unfortunately. As for the egg shape thing - I don't think that would work either, to be honest, considering it's a 50/50 chance of any egg being female or male.

 

[Harmony Fowl]

I had an accidental test with lower temps. Well, the temp in the incubator wasn’t consistent and there were too many and not enough warm spaces to go around despite rotation. Only seven chicks hatched, two with assistance, out of 41 eggs. Those two and one other died. The survivors? Four boys, despite every other hatch I’ve had be no more than one chick off 50/50 male/female. Four isn’t a significant enough sample size, but it makes me suspect males may be more tolerant of less than ideal incubation conditions.

I think it was Cynthia Moss who did a study of elephants years ago. Basically, in a drought, only female calves survived. She hypothesized that male calves required greater investment from their mothers, a greater investment the cows could ill afford to spare in a drought.

Similarly, I remember from college that when human babies are born prematurely, survival rates are better than girls than for boys. If I remember right again, there are slightly more women than men in the world. The possible explanation being that females are slightly more tolerant to adverse conditions than males and more likely to survive them. In mammals there could be some kind of relation to having two of the same sex chromosome lending itself to greater stability of life. With birds, of course, those roles are reversed and males are the ones with two of the same sex chromosomes, which could explain why I had only male survivors in hostile hatching conditions. Equal numbers of male and female embryos are conceived, but more males survive.

But this is all grasping at barely remembered straws from long ago and just suspicion on my part. I hope you’ll continue to share your experiments with us, OP.

 

[VintageLilFarm]

I stored eggs in the fridge for 4 weeks and longer. They are 10 weeks old now. Lots of boys.

LOL! So maybe NO!

 

[VintageLilFarm]

I had an accidental test with lower temps. Well, the temp in the incubator wasn’t consistent and there were too many and not enough warm spaces to go around despite rotation. Only seven chicks hatched, two with assistance, out of 41 eggs. Those two and one other died. The survivors? Four boys, despite every other hatch I’ve had be no more than one chick off 50/50 male/female. Four isn’t a significant enough sample size, but it makes me suspect males may be more tolerant of less than ideal incubation conditions.

I think it was Cynthia Moss who did a study of elephants years ago. Basically, in a drought, only female calves survived. She hypothesized that male calves required greater investment from their mothers, a greater investment the cows could ill afford to spare in a drought.

Similarly, I remember from college that when human babies are born prematurely, survival rates are better than girls than for boys. If I remember right again, there are slightly more women than men in the world. The possible explanation being that females are slightly more tolerant to adverse conditions than males and more likely to survive them. In mammals there could be some kind of relation to having two of the same sex chromosome lending itself to greater stability of life. With birds, of course, those roles are reversed and males are the ones with two of the same sex chromosomes, which could explain why I had only male survivors in hostile hatching conditions. Equal numbers of male and female embryos are conceived, but more males survive.

But this is all grasping at barely remembered straws from long ago and just suspicion on my part. I hope you’ll continue to share your experiments with us, OP.

Very interesting! I will update in a week.

 

[VintageLilFarm]

The temperature thing isn't true, unfortunately. As for the egg shape thing - I don't think that would work either, to be honest, considering it's a 50/50 chance of any egg being female or male.

That is my suspicion as well, or it seems hatcheries and other financially invested folks would have succeeded in predominantly girl hatches by now.

 

[lazy gardener]

I have read the studies regarding storage temp. I have done the egg shaped gender experiment 4 times. I would never choose to set eggs at a lower than recommended temp b/c it leads to congenital defects.

As for the egg shape: prior to doing this experiment, all my hatches resulted in 60% male. When doing the first 3 egg shaped sets, my hatches were 60% female in each of the 2 bator and 1 broody hatches. The 4th egg shaped gender set resulted in 50% pullet rate.

 

[VintageLilFarm]

I have read the studies regarding storage temp. I have done the egg shaped gender experiment 4 times. I would never choose to set eggs at a lower than recommended temp b/c it leads to congenital defects.

As for the egg shape: prior to doing this experiment, all my hatches resulted in 60% male. When doing the first 3 egg shaped sets, my hatches were 60% female in each of the 2 bator and 1 broody hatches. The 4th egg shaped gender set resulted in 50% pullet rate.

I did not know that about lower temps resulting in issues. I thought just later hatch date. Thanks for mentioning. I'm going to look into that, and maybe turn mine back up to 99.5.