Why is my white Jersey Giant not giant?

[Hablo]

Hi there!
I bought 4 Jersey Giant hens in March. They are from natural breeding and siblings. Now they are 11 months old.
I've got 3 black ones and one white one.
But why is my white hen so slim? Is she still gaining mass? Is she just growing slower? In comparison you can see one of my giant black hens.

Greetings from the Franconian Switzerland in Germany,
Hablo

 

[NatJ]

Hi there!
I bought 4 Jersey Giant hens in March. They are from natural breeding and siblings. Now they are 11 months old.
I've got 3 black ones and one white one.
But why is my white hen so slim? Is she still gaining mass? Is she just growing slower? In comparison you can see one of my giant black hens.

Have you weighed each of them, or picked them up to see how heavy they are? Sometimes fluffy feathers can make one chicken look much bigger than another, even when their bodies are actually the same size.

If she really is smaller (lighter), then maybe she could be half Leghorn instead of pure Jersey Giant. Crossing a Black Jersey Giant with a White Leghorn could produce hens that look like her (slim body, mostly white with a few bits of black in the feathers.) A rooster or hen getting into the wrong pen is an obvious way to have accidental mixed chicks. If the breeder was expecting some white chicks anyway, it might take a while to notice that some of the white ones are not the same body type as the others.

Or if someone started with Black Jersey Giants and wanted white ones, they could have crossed with White Leghorn or some other white breed to get the white, then worked on breeding back toward correct Jersey Giant traits. It would take a number of generations to recover the size and body type. Your white pullet could have come from a project like that, not all the way back to Jersey Giant size and body type.

 

[Hablo]

Have you weighed each of them, or picked them up to see how heavy they are? Sometimes fluffy feathers can make one chicken look much bigger than another, even when their bodies are actually the same size.

If she really is smaller (lighter), then maybe she could be half Leghorn instead of pure Jersey Giant. Crossing a Black Jersey Giant with a White Leghorn could produce hens that look like her (slim body, mostly white with a few bits of black in the feathers.) A rooster or hen getting into the wrong pen is an obvious way to have accidental mixed chicks. If the breeder was expecting some white chicks anyway, it might take a while to notice that some of the white ones are not the same body type as the others.

Or if someone started with Black Jersey Giants and wanted white ones, they could have crossed with White Leghorn or some other white breed to get the white, then worked on breeding back toward correct Jersey Giant traits. It would take a number of generations to recover the size and body type. Your white pullet could have come from a project like that, not all the way back to Jersey Giant size and body type.

Thanks for your answer!
No, I haven't weighed them, but I picked them up and she is definitely lighter. I mean, the height of her is the same, but she has less muscles.
The guy from whom I bought them, said he only owned Jerseys when they hatched naturally and then these 3 blacks hatched and the white one. So if this was a Leghorn mix, then he should have had a Leghorn rooster or a hen, but as he said, he only had Jersey Giants at that time.

 

[NatJ]

Thanks for your answer!
No, I haven't weighed them, but I picked them up and she is definitely lighter. I mean, the height of her is the same, but she has less muscles.

Okay, that shows it is a real difference, not just feathering.

The guy from whom I bought them, said he only owned Jerseys when they hatched naturally and then these 3 blacks hatched and the white one. So if this was a Leghorn mix, then he should have had a Leghorn rooster or a hen, but as he said, he only had Jersey Giants at that time.

I agree, the father should be one of the roosters he owns, unless a neighbor's rooster came visiting or unless he just got the hens and they had previously mated with a Leghorn or some other kind of chicken (hens can store sperm for over a week, sometimes over a month, then lay a fertile egg, that hatches into a chick with a father who has been gone for almost two months.)

Does the guy have some White Jersey Giants in his flock, or just the black ones? If he has white ones, are his whites smaller than his blacks? Maybe the whites just are smaller

 

[Hablo]

Okay, that shows it is a real difference, not just feathering.


I agree, the father should be one of the roosters he owns, unless a neighbor's rooster came visiting or unless he just got the hens and they had previously mated with a Leghorn or some other kind of chicken (hens can store sperm for over a week, sometimes over a month, then lay a fertile egg, that hatches into a chick with a father who has been gone for almost two months.)

Does the guy have some White Jersey Giants in his flock, or just the black ones? If he has white ones, are his whites smaller than his blacks? Maybe the whites just are smaller

I asked him again. He said:
"Well, I'm 100% sure she's purebred. But my personal experience with white chickens is that they're always a little behind or don't develop quite as well as the others."

 

[NatJ]

I asked him again. He said:
"Well, I'm 100% sure she's purebred. But my personal experience with white chickens is that they're always a little behind or don't develop quite as well as the others."

That is definitely interesting. Now I'm wondering why that would be. It is easy enough for genes to have multiple effects (like feather color and feather texture, or a comb gene that also affects the wattles), but I don't yet know of anything specific that goes with white feather color.

But it sounds like you do have the answer about your specific chicken: it is normal for that color of chicken, according to the experience of the breeder you got her from.