Can we hatch more hens and fewer roosters?

A friend of mine some years ago, told me she had met an old Chinese man who would select only the rounded eggs for his hens to raise into chicks so he would get only hen chicks. I tried it and ended up with a flock of 2 roosters and 25 hens not counting the chickens that I started with. I inspected the eggs when a hen went broody and only left eggs that were clearly rounded on the small end of the egg. I wonder if the eggs that were in between were infertile. The eggs that were more pointed were supposed to become roosters. It needs more testing if anyone is interested in experimenting.

I've heard this and about a hundred other ways to get more of one or the other. Brooding tempature is what determines what the predominant sex will be, if your brooding under a hen more times than not you'll get predominatly females, unless she does her brooding in a enclosed area that will retain heat. If brooding in an incubator, temp. settings kept as close to 98.4 will produce a majority of females while 100.4 will produce a majority of males. Even with temps in those ranges we will still get about a 70/30 split. For most backyard/barnyard chicken production the incubators needed to reliably achieve the tempature tolerances reliably are cost prohibitive, to get a majority of females, use nature to your advantage, let your hens set out of the coop, on or as close to the ground as possible and you should do well. I've never seen any brood of chicks come off all female or male, there will always be a mix, you can only manipulate so much.

I did a search out of curiosity and on the backyard chicken forum there is a thread on this. the first link is about a patent to use computers to tell gender by egg shape but the link seems to no longer work

http://www.backyardchickens.com/t/631489/you-can-sex-a-chicken-egg

also further down in the thread are these links
http://www.motherearthnews.com/homesteading-and-livestock/buying-fertilized-chicken-eggs-zmaz74zhol.aspx

and
http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=2176640

and this person claims to have tried it once with 100% success. they are not saying it would always work so well but it sound slike it certainly can work
http://www.backyardchickens.com/t/631489/you-can-sex-a-chicken-egg/10#post_8454025

now what I am wondering is. can this work with duck eggs?

Interesting about the temperature control. I had assumed that the sex was genetically controlled like mammals but I have read somewhere that reptile traits can be environmentally controlled so it makes sense. Is that how the commercial suppliers of chicks offer all female? I purchased 24 by mail and got 2 roosters out of the bunch. I have enough chickens now but I have been curious about this.

I'm pretty sure that chickens' sex is determined by genetics. Reptiles use temperature.

according to this a drop of temperature can change the sex of chickens while they are forming in their eggs

http://www.independent.co.uk/news/a-drop-in-temperature-can-change-the-sex-of-chickens-1238516.html


perhaps a combination of egg shape and temperature control would provide the best results.
and here is part of it with a bit of a warning about breeding functional hens that have male genetics
"They have the genes and chromosomes for maleness but they are fully functional females able to lay fertile eggs. If they are then crossed with normal males, the resulting chicks are all male, said Professor Mark Ferguson of the University of Manchester."

Hatcheries "sex" chicks and separate them for sale, there's a couple of ways to do it, there's even some videos on u-tube on how to.
We hatch several hundred chicks per year, and we get request for males and for females, brooding temps will make a difference in chickens as much as reptiles.

I had a hard time setting my Buff Orpington eggs in my incubator because both ends of the egg are the same. Most eggs I can't tell the difference.  Si I candle the ones in doubt to find egg sac.