Ameraucana thread for posting pictures and discussing our birds

[StelleKitten]

Technically the female determines the gender of the chicks. But this is an interesting puzzle!

So chickens have different chromosome setup than humans. I know in humans, the sex of a baby is determined by the male. I cant remember if it is x or y that determines this. Been a few years since school.

 

[Fyremare]

So chickens have different chromosome setup than humans. I know in humans, the sex of a baby is determined by the male. I cant remember if it is x or y that determines this. Been a few years since school.

http://www.backyardpoultrymag.com/issues/6/6-3/determining_sex_in_chicks.html

 

[StelleKitten]

Sex Determination in Birds: Z and W Chromosomes

Figure 3: FISH mapping of DMRT1 on chicken Z chromosome.
a. Hybridization of DMRT1 cosmid to a female chicken metaphase spread. b. DAPI banding of the same metaphase spread, converted into G-like bands. c. G-banded karyotype of chicken macrosomes hybridized with DMRT1 (green spot on Z chromosome).
Copyright 1999 Nature Publishing Group. Nanda, I., et. al., 300 million years of conserved synteny between chicken Z and human chromosome 9, Nature Genetics, 21, 258 - 259
In birds, sex is determined by chromosomes known as the Z and W, and females are the heterogametic sex. Early on, it was apparent that there were notable differences in the mechanisms used for sex determination in birds and mammals. Working with chickens, scientists were unable to find a counterpart of the SRY gene required for mammalian testis determination, so they searched for homologues of other genes that were required for testis formation in mammals. These investigations led to the discovery of the DMRT1 gene on the chicken Z chromosome (Nanda et al., 1999).
In mammals, the DMRT1 gene product is a critical member of the testis-forming pathway initiated by SRY. Two copies of the DMRT1 gene are necessary for testis development, even in the presence of SRY. In mammals, both sexes have two copies of DMRT1, because it is located on an autosome (specifically, chromosome 9). In chickens, by contrast, only males possess two copies of DMRT1, as it is located on the Z chromosome. Figure 3 shows the results of an in situ hybridization experiment in which a DRMT1 probe has been hybridized to the chromosomes of a female chicken. Figure 3b shows the appearance of the chromosomes under a microscope, and Figure 3a shows that the DRMT1 probe hybridizes to a single region on the female's Z chromosome. (These are metaphase chromosomes, so hybridization is detected on the two sister chromatids.) Figure 3c shows selected chromosomes in a partial karyotype. One can readily see that the Z chromosome is significantly larger than the W chromosome.
The actual trigger for activating the testis-forming pathway in chickens remains unknown. Birds also differ significantly from mammals in that two unique genes on the W chromosome, FET1 and ASW, are necessary for female development. The function of FET1 is unknown, but it is expressed in the gonads leading up to the time of sexual differentiation (Smith & Sinclair, 2004). Like mammals, chickens also have an indifferent gonad until around day four of development, after which an ovary or a testis starts to develop. Hormones then orchestrate the development of other sex-specific characteristics. In contrast with mammals, however, estrogen is required earlier in sex determination in chickens, and is, in fact, necessary for formation of the ovary. In fact, genetically male chickens can be converted to females if eggs are injected with estrogen at the sensitive stage of development.
The ZZ-ZW mechanism of sex determination is not restricted to birds. Within the vertebrates, a similar system of sex determination has been identified in reptiles, as well as in some fishes and amphibians.

sourced from
http://www.nature.com/scitable/topicpage/genetic-mechanisms-of-sex-determination-314

 

[Phage]

1. In other words the FEMALE chicken determines the sex of the chick, or rather each egg if fertilizer by a rooster (regardless of the rooster).

2. Each egg as it is made already has a pre determined sex.

3. Not like humans/mammals, and not like some reptiles.

4. Changing the temperature of incubation CAN NOT change the sex of developing chicks in eggs, it will just lead to more death in weak chicks.

5. If temperature could determine sex of chicks in eggs hatcheries would not be hatching 50% roos.


***edited to say, that is unless you have a molecular genetics laboratory and then you can make what you like.....

 

[StelleKitten]

Sorry I didnt make myself clear before, I was correcting myself. I posted a few seconds after the previous post, so didnt see it until AFTER I had posted.

 

[sandiklaws]

So chickens have different chromosome setup than humans. I know in humans, the sex of a baby is determined by the male. I cant remember if it is x or y that determines this. Been a few years since school.

http://faculty.weber.edu/rmeyers/chicken sex determ.pdf
you are correct, the chickens have a different chromosome set up

 

[dak]

So, like I was saying. it is the genetic make-up NOT temperature. Anyone can flip a coin and see runs of heads or tails, but do it a million times and it will be close to 50/50.

 

[johnderosa1]

Phage's comment number 5 is all you need to know on this subject... If the pros could change the economics of their business model by adjusting incubator temps, they would. End of story.

 

[CCCCCCCCHICKENS]

YAY putting some eggs in the incubator! 4 blue AMs and 3 white AMs.

 

[Hangtown Farms]

Sending you a PM.

Jerry I dont think I saw the Pm if you sent it.