Genetics question......

[bauerdog]

I am curious about the final feather color of chicks from a specific combo. I had a blue Marans rooster with gold leakage. He came from a blue cuckoo roo over a blue marans. He covered a sapphire hen (crested cream legbar over a white leghorn). I let a broody hatch out 2 of her eggs. The first chick hatched out black with a very sharp head spot and the Marans fluff on the legs. Does this indicate a sexable chick? Both parents probably have a cuckoo gene......would a head spot mean a male or female? And should I expect a cuckoo coloration?

 

[Wappoke]

I am curious about the final feather color of chicks from a specific combo. I had a blue Marans rooster with gold leakage. He came from a blue cuckoo roo over a blue marans. He covered a sapphire hen (crested cream legbar over a white leghorn). I let a broody hatch out 2 of her eggs. The first chick hatched out black with a very sharp head spot and the Marans fluff on the legs. Does this indicate a sexable chick? Both parents probably have a cuckoo gene......would a head spot mean a male or female? And should I expect a cuckoo coloration?

this is not a true sex linked cross because you can not sex all the chicks with any degree of accuracy. The head spot means the bird is carrying the barring gene and if I am interpreting your descriptions correctly, the chick is a male.

My answer is based upon the following, the blue marans is not carrying barring (if he did he would be blue barred) and the sapphire hen inherited a sex linked barring gene from the legbar rooster (the legbar was homozygous for sex linked barring)

the saphire hen is carrying dominant white- some of the chicks will be white or white with black spots, you can not sex the white chicks with a reasonable degree of accuracy

 

[bauerdog]

Hmmmmmm. Does this look like 2 males then?

 

[Wappoke]

Hmmmmmm. Does this look like 2 males then?

My guess would be; the one on the left appears to be a male, the one on the right could be a male or female. Some of the male chicks will receive two barring genes and the others will inherit one barring gene. The females- some will inherit a barring gene and some will be non-barred.

Sexing chicks by the size and shape of the head spot on a dark ground color is an inaccurate way of sexing chicks- around 75% in a normal barred rock cross. In your cross ( the chicks that do not have white down), the probability of hatching a male chick with a head spot is greater than hatching a female chick with a head spot. All the males will have a head spot and only half of the females will have a head spot.

If you hatched out a large number of chicks some of the chicks would be white or white with black spots.

 

[bauerdog]

These were the only two. I was only placating a broody. I wound up with a double barred male and a single barred female.

 

[bauerdog]

Thank you for the great explanation. Genetics is very interesting, but overwhelming to sort out on your own without help