Temperature/humidity changes ratio of sexes?

[TamiTrojan]

I have heard it discussed that male and female embryos have different temperature tolerances and that you might effect different hatch rates by manipulating temperature. My last two hatches consisted of 5 chicks (4 roos and 1 hen) and my latest of 6 chicks (4 roos and 2 hens). Am I doing something that is causing me to be so far from 50-50? It's so hard to find homes for bantam roos in my area!!!

I've read of people buying refrigerated fertile eggs from Trader Joe's to hatch...curious what the sex ratio is...

I also have 2 sons, 0 daughters...maybe it's just me!

Looking for advice,
Surrounded by testosterone in Southern Cali

 

[Pyxis]

There have been some studies done that imply that female embryos are more cold tolerant than male embryos, meaning if you refrigerate the eggs you are likely to hatch a higher number of pullets than cockerels. Note that this doesn't mean you've changed the gender of the embryos - what you've done is killed off some of the males. So while you will get a higher ratio of females, your hatch rate overall will be lower because what happened is the males simply died and didn't hatch.

You are not affecting the gender ratio of your chicks during incubation. Just as with humans, the gender of the chick is determined at the moment of conception by which sex chromosomes it received.

Quick edit: Here's one study talking about it, but it's about duck eggs and about exposing them to cold during incubation, not before: http://www.jstor.org/stable/3799426?seq=1#page_scan_tab_contents

I can see if I can dig up the chicken egg one if you want.

Edit again, I found the chicken one also: http://www.publish.csiro.au/paper/AR9600664.htm

 

[TamiTrojan]

Thank you! I do know I'd be killing off the rooster embryos to try it, but I'd rather stop them before they really start and not worry about how to re-home them, and making sure they don't end up with someone with nefarious intentions... (I live in a city that does not allow roosters, and near a big city that has some cock fighting trouble) I'm headed to check out the link. I'm ordering shipped eggs, so I hate to lower my hatch rate further, but it is so heartbreaking to end up with so many roos!

 

[MeepBeep]

Thank you!  I do know I'd be killing off the rooster embryos to try it, but I'd rather stop them before they really start and not worry about how to re-home them, and making sure they don't end up with someone with nefarious intentions... (I live in a city that does not allow roosters, and near a big city that has some cock fighting trouble)  I'm headed to check out the link.  I'm ordering shipped eggs, so I hate to lower my hatch rate further, but it is so heartbreaking to end up with so many roos!

IMO unless you are hatching a lot of eggs the risk of killing off female viable eggs in an attempt to kill off the males it simply not worth the effort... From experience and many other peoples experiences a 50% hatch rate on shipped eggs is pretty much the norm, but lower hatch rates are quite common... Why expose those already low hatch rates to more torture and push the hatch rates even lower doing something that for all intents is a roll of the dice?

The linked article for chickens suggest a 54.6% pullet ratio vs the expected 50% at 40°, that is IMO is likely just an anomaly unless the full article repeated the ratio multiple times... And even if it isn't the 4.6% difference amounts to about 1 more pullet per 24 hatched eggs, but the article also suggest many more 'clears' at the 40° temp, so you are not just killing off roos...

I just don't see how possibly improving your odds for 24 hatched eggs from 12 Pullet : 12 Rooster to 13 Pullet : 11 Rooster is worth it when you also factor in the kill off of both sexes from the temp drop...

And if you are hatching less than 24 eggs, there is for all intents no statistical difference in the hatch ratio...

A vast majority of any rooster sold/given away are destined for the slow cooker or animal feed, as my 4 & 6 year old daughters say 'It's the Circle of Life"

Illegal cock fighters have about as much need for garden variety chickens as illegal dog fighters have for toy lap dogs...