Is it true that a lower temp makes more girls?

[Ducks and Banny hens]

Is sex always determined in every species through genetics? Because I have definitely heard that most reptiles' sexes are determined by temperature.

Again, I think this is a confusion; Most boys (which are already set out to be boys) will do very well in high temperatures; Most girls (which are already etc. etc.) will do very well with lower temperatures, increasing each sexes' chance of survival.

 

[Tahai]

Howdy.

All mammals' and birds' sexes are determined by genetics. Some reptiles' sexes can be determined by temperature. See this article for an explanation.

http://www.scientificamerican.com/article.cfm?id=experts-temperature-sex-determination-reptiles

 

[Speceider]

Howdy.

All mammals' and birds' sexes are determined by genetics. Some reptiles' sexes can be determined by temperature. See this article for an explanation.

http://www.scientificamerican.com/article.cfm?id=experts-temperature-sex-determination-reptiles

I would not make the mistake of equating mammalian and avian genetics...comparing apples and oranges. Reports of avain TSD occur often enough to question the possibility. I have my own beliefs of the possibility. Is it TSD or differential embryo survival....I don't know and don't have the data either way. Clint

 

[mandelyn]

I have NEVER hatched a boy duck. I have done 3 batches of eggs, 1 was a 100% hatch, ALL girls. One batch was 6 eggs, shipped, 2 made it to lock down, 1 hatched, female. Another... "scavenged" Pekin eggs from a local park where they just laid them on shore... 11 eggs, 5 hatched, ALL girls.

My temperature is chronically too high. No matter where I put the incubator in the house or how little I turn the dial... I can spend a week or more calibrating it, and it will only maintain a consistent temperature (with a digital thermometer) at 98.9 or 100.9. I used the 100.9.

With chickens, I have done several batches of eggs. Only 2 boys. All different sources.

So based on personal experience... I say No. I would need to try the 98.9 temp and see the results. LOL

ETA: I will be hatching my own eggs soon... I'm curious to see if the same process yields the same results, or if it was flukes every time before.

 

[CelticOaksFarm]

This is our son science research project this year. Temperature of the incubator only helps in culling before hatch one gender or the other. High temps pulls more male hatchlings, lower temps pulls more female. But the change in temps also equals a poor hatch total number, because of those eggs predetermined to be male or female not hatchlings at the higher or lower temp. He has ran this test from last September until this next week. Needless to say we have large batches of males hatched that have been culled since.

 

[DB_Tex]

I wonder if hatcheries are onto this and try to doctor the numbers of hatchlings toward the more heavily desired sex?

 

[Ducks and Banny hens]

I wonder if hatcheries are onto this and try to doctor the numbers of hatchlings toward the more heavily desired sex?

That's a distinct possibility. If hatcheries can prevent cockerels from forming, they don't have to do away with so many. (I won't go into what some hatcheries do....

)

 

[WestKnollAmy]

I have never changed my settings to acquire more of one sex but I have had times where more males hatch and other times where more females hatch in ducks, Guineas and chickens. My Sportsman temp runs consistently at 100.5. I only candle on day 18 and move them all to the hatcher which is a Genesis 1588 where they hatch at 100.9.
Do you think humidity would have anything to do with it?