Does the rooster or the hen determine the sex of the chick

Egglive · **Joined:** Fri Dec 14, 2007 10:58 am **Posts:** 267

Everything I've every seen about gender says that it's 1:1 but I was browsing around and found this:

Recent studies of several avian species have shown that the primary sex ratio can change as a result of prevailing conditions, especially in the female bird's first reproductive season. In this study, we sought to determine the primary sex ratio of the first 15 eggs produced in chickens. The study compared chickens which had been commercially selected over many generations for egg-laying performance (Leghorns) with "fancy-bred" chickens selected for feather coloration. These fancy-bred chickens are known to reach reproductive maturity 4 weeks later than Leghorns. A group of precociously matured Leghorn chickens was produced by modification of diet and day length to investigate the effect of age at reproductive maturity on sex ratio. Sex diagnosis was performed on embryos which had died on or before embryonic day 10 by polymerase chain reaction (PCR). Living embryos were allowed to hatch before sex diagnosis. The group of precociously matured White Leghorns reached egg-laying age 3 weeks earlier than normal. In this group, the sex ratio of hatched chicks was in tendency skewed to females. In the White Leghorns maintained under normal conditions for commercial layers, sex ratio was balanced with a tendency to more males only in the first five eggs. In the group of fancy-bred chickens, the primary sex ratio was significantly biased toward more males and dependent on the laying sequence. Our data suggested a sex ratio bias toward males in the very first eggs at onset of reproduction in chickens depending on genetic background. http://www.ncbi.nlm.nih.gov/pubmed/18030680 (That's only the abstract of course).

That German study (Jan 2008) opens up some new possible explanations. Have people on this forum found that first eggs produce more males? Can't say that I've taken too much notice, but I will from now on. I would also like to know what other 'prevailing conditions' can affect the gender ratio - the abstract didn't say.

greenaus · **Posted:** Wed May 14, 2008 6:44 pm

For those like me who wondered what "precociously matured" might mean, here is the definition of precocious.

1 : exceptionally early in development or occurrence <precocious puberty>
2 : exhibiting mature qualities at an unusually early age <a precocious child>

For those who already knew...

rocky · **Joined:** Mon Apr 28, 2008 3:36 pm **Posts:** 144

15 eggs is a very,very small sample.

greenaus · **Posted:** Wed May 14, 2008 9:07 pm

...unless it was the "first 15 eggs produced" per pullet.

I believe the experiment was to determine what sexes would hatch from the first 15 eggs of each of the pullets in the "group of precociously matured Leghorn chickens".

duckie · **Posted:** Thu May 15, 2008 11:19 am

Charlie, I am not trying to hatch only pointy eggs

. I am trying to hatch round eggs . if this is true about the shape I want more hens and only getting more roos even a small difference in shape could tell the story. Sometimes this could work ... but as in the event of 2 bantam eggs both fairly round, both were (are) roos. It may depend on the size and/or the breed of the parents of the eggs. I have been told by a few breeders over the years (one recently from Beaudesert) about the shape.

I have been told that GLW eggs are round like a ball. Is that true, if so how would you tell the difference in the sex while an egg. ?

I am interested in a couple of GLW hens (very soon) as I have a roo.

I believe that the sex is determined while an egg. They are not reptiles and temperature could not make a difference. If it did, then we would never have enough roos to breed with. How would the temperature be controlled while hatching naturally and under the hen. She can't switch her body temp off and on at will now can she?

blackdave · **Posted:** Thu May 22, 2008 2:09 pm

may I suggest, sexing chicks after hatching its easier
Once hatched, just follow the string bag method
1) collect all chickens of same age
2 Place in standard string shopping bag
3)Jump up & down whilst holding bag
Sexing is automatic as all the little pricks will fall out !!
HO HO HO

Peter16 · **Posted:** Thu May 22, 2008 3:04 pm

blackdave wrote:

may I suggest, sexing chicks after hatching its easier
Once hatched, just follow the string bag method
1) collect all chickens of same age
2 Place in standard string shopping bag
3)Jump up & down whilst holding bag
Sexing is automatic as all the little pricks will fall out !!
HO HO HO

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