New Posts  All Forums:Forum Nav:

temp and sex - Page 2

post #11 of 12

  i knew I had just read something on this.....   found this -   A study in Australia (Australian Journal of Agricultural Research 11(4) 664 - 672) has shown that eggs stored at 40 degrees Fahrenheit (rather than the recommended 60 degrees) hatch out more females than males. However storing your eggs at colder temperatures before hatching doesn't actually change the ratio of male to female eggs. It has been shown that the male embryos are preferentially killed off by colder storage temperatures, while the female embryos handle the chilling better.

post #12 of 12
Chicken sex chromosomes are Z and W. Somewhat like the X and Y chromosome in humans. The difference is that in humans the female is XX and the XY chromosomes of the male determine the sex of the child. If the haploid sperm gamete the does the fertilization contains the X chromosome the the child will be a female. If it contains the Y chromosome, then the child will be male. In chickens the male sex chromosome is ZZ and the female is ZW. Therefore it is the female chromosomes that determines the sex of the chick. The process of meiosis produces four Haploid sperm cells each containing one Z chromosome whereas I the female meiosis produces four haploid cells. Two with the Z chromosome and two with the W chromosome. Of these four only one survives with a 50/50 chance of it being a Z or W chromosome. These means that half the eggs produced by the hen will have the female producing W chromosome and half will contain the male producing Z chromosome. Once fertilization occurs the sex of the chick is imediately determined. Any variation of temperature, during incubation, would only lead to more Roos or hens, if a higher or lower temperature lead to the demise of one sex or the other. In other words, if female chick are more susceptible to death at higher temperatures then you will have a higher percentage of males because the embryos that don't develop or die before hatching would mostly be females. If them male chicks are more susceptible to death at lower temps then you will have more hens at lower incubation temps because those that don't hatch would more likely be males. (I don't know this to be the case but that might explain the discrepancy in the ratios of chicks. If one were to have an unheard of 100% hatch rate the ratio will be approximately 50/50. Hope that helps
New Posts  All Forums:Forum Nav:
  Return Home
  Back to Forum: Incubating & Hatching Eggs