# Law of Probability - Hen or Rooster

Discussion in 'Incubating & Hatching Eggs' started by Ducati, Apr 15, 2009.

1. ### DucatiOut Of The Brooder

39
0
32
Mar 4, 2009
Heres is a dumb question, which I think I already know the answer to. What are the chances out of the 12 eggs that hatched last week of mine, some will be males? Logic is telling me 50/50, since there are only two options. Or do some breeds tend to produce more males than females? I hatched 6 White Leghowns, and 6 Buff Orp last week. How many roosters should I expect out of 12?????

2. ### BirdBrainPrefers Frozen Tail Feathers

May 7, 2007
Quote: 12.........Then be grateful for any that aren't.

4 people like this.
3. ### peacefulChillin' With My Peeps

Jun 24, 2008
I've heard that incubators that are run a little high in temperature can produce more roosters because the female embryos are more susceptible to the heat and tend to die off. So if you had fertilized eggs that didn't make it and your incubator temperature was on the high side then you could get more roosters than hens. Thus this would alter the 50/50 hatch rate.

Also I remember from psychology class that in the human population there tend to be slightly more males born (54% if my memory serves me), but that they die off younger (probably from aggression etc) so that after a certain age proportionally there are more females, in human population statistics.

4. ### mediazealChillin' With My Peeps

1,476
14
181
Feb 26, 2009
Quote:that's murphy's law (which overtakes the laws or probability and makes the peanut butter and jelly sandwich land jelly side down).

I'm planning on 50% of each but hoping for all hens of course.

5. ### horsejodySqueaky Wheel

6,923
27
271
Feb 11, 2008
The odds are that you will get 50-50.

6. ### moomanDirty Egg Eater

86
1
41
Apr 9, 2008
Marietta, SC
Unlike reptiles and some other "lower" vertabrates, whose sex can be determined by the temperature at which they are incubated, chicken sex is determined the same way ours is (by sex chromosomes).

Half of the roosters sperm contain an X chromosome, the other half contain a Y chromosome.

If an egg is fertilized by a Y sperm the resulting offspring is male. If the egg is fertilized by a sperm that contains an X chromosome the offspring is female.

Fertilization is random so the probablility is that you will get a 50/50 mix........but try tossing a coin 12 times and you will see you rarely get 6 heads and 6 tales. If you continue to toss the coin long enough you might even get a round with all heads and no tails

7. ### mediazealChillin' With My Peeps

1,476
14
181
Feb 26, 2009
Quote:Ah, yes, but does this hold true when one rooster is all that is needed for several hens? More hens would mean more chicks...
enough roosters that they could vie for the honors and the best roo winning would not mean they have to be more than 50%

Interesting question.

I've heard the high heat = roosters, but I've also heard that is an old wives tale.......

Anyway, wishing us all healthy hatches with lots of hens.

8. ### backpack09Out Of The Brooder

94
2
41
Mar 20, 2009
Whitman, MA
2 people like this.
9. ### patandchickensFlock Mistress

12,520
136
341
Apr 20, 2007
In general the odds of a particular egg being m/f are basically 50/50. I have read that 'off' incubation temperatures will bias the hatching sex ratio by killing off very slightly more of one sex than the other on average (I forget which way it was said to go), and I am certain there are sexlinked lethal or deleterious genes in chickens such that *if* the embryos were carrying 'em, it could bias the sex ratio.

However, I think that BY FAR the best bet is for basically a 50/50 chance.

The odds of your getting 12 eggs to hatch as exactly 6 males and 6 females are not really all that high, though.

The odds of it being all 12 males, or all 12 females, are pretty low though (too lazy to find my good calculator, but it should be 0.5 to the 12th power IIRC, or twice that if you just want odds of all-one-sex-no-matter-which)

Have fun,

Pat

10. ### pascopolChillin' With My Peeps

1,472
20
184
Jan 6, 2009
Tampa Bay
Quote:50/50 odds are truer for higher total numbers. lets say you were hatching 100 or more.

With 12 eggs (assuming they all hatch) you will very likely get 5/7 6/6 or 4/8 split either sex.

The odds of getting 12 males or 12 females are 2x2x2x2x2x2 =

1:64

Much better chance than hitting the Lotto LOL